Move source from 'buildstream' to 'src/buildstream'

This was discussed in #1008.

Fixes #1009.

44 files changed, 8274 insertions, 0 deletions

diff --git a/src/buildstream/_protos/__init__.py b/src/buildstream/_protos/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/__init__.py
diff --git a/src/buildstream/_protos/build/__init__.py b/src/buildstream/_protos/build/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/build/__init__.py
diff --git a/src/buildstream/_protos/build/bazel/__init__.py b/src/buildstream/_protos/build/bazel/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/__init__.py
diff --git a/src/buildstream/_protos/build/bazel/remote/__init__.py b/src/buildstream/_protos/build/bazel/remote/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/remote/__init__.py
diff --git a/src/buildstream/_protos/build/bazel/remote/execution/__init__.py b/src/buildstream/_protos/build/bazel/remote/execution/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/remote/execution/__init__.py
diff --git a/src/buildstream/_protos/build/bazel/remote/execution/v2/__init__.py b/src/buildstream/_protos/build/bazel/remote/execution/v2/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/remote/execution/v2/__init__.py
diff --git a/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution.proto b/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution.proto
new file mode 100644
index 000000000..7edbce3bc
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution.proto
@@ -0,0 +1,1331 @@
+// Copyright 2018 The Bazel Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package build.bazel.remote.execution.v2;
+
+import "build/bazel/semver/semver.proto";
+import "google/api/annotations.proto";
+import "google/longrunning/operations.proto";
+import "google/protobuf/duration.proto";
+import "google/protobuf/timestamp.proto";
+import "google/rpc/status.proto";
+
+option csharp_namespace = "Build.Bazel.Remote.Execution.V2";
+option go_package = "remoteexecution";
+option java_multiple_files = true;
+option java_outer_classname = "RemoteExecutionProto";
+option java_package = "build.bazel.remote.execution.v2";
+option objc_class_prefix = "REX";
+
+
+// The Remote Execution API is used to execute an
+// [Action][build.bazel.remote.execution.v2.Action] on the remote
+// workers.
+//
+// As with other services in the Remote Execution API, any call may return an
+// error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+// information about when the client should retry the request; clients SHOULD
+// respect the information provided.
+service Execution {
+  // Execute an action remotely.
+  //
+  // In order to execute an action, the client must first upload all of the
+  // inputs, the
+  // [Command][build.bazel.remote.execution.v2.Command] to run, and the
+  // [Action][build.bazel.remote.execution.v2.Action] into the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+  // It then calls `Execute` with an `action_digest` referring to them. The
+  // server will run the action and eventually return the result.
+  //
+  // The input `Action`'s fields MUST meet the various canonicalization
+  // requirements specified in the documentation for their types so that it has
+  // the same digest as other logically equivalent `Action`s. The server MAY
+  // enforce the requirements and return errors if a non-canonical input is
+  // received. It MAY also proceed without verifying some or all of the
+  // requirements, such as for performance reasons. If the server does not
+  // verify the requirement, then it will treat the `Action` as distinct from
+  // another logically equivalent action if they hash differently.
+  //
+  // Returns a stream of
+  // [google.longrunning.Operation][google.longrunning.Operation] messages
+  // describing the resulting execution, with eventual `response`
+  // [ExecuteResponse][build.bazel.remote.execution.v2.ExecuteResponse]. The
+  // `metadata` on the operation is of type
+  // [ExecuteOperationMetadata][build.bazel.remote.execution.v2.ExecuteOperationMetadata].
+  //
+  // If the client remains connected after the first response is returned after
+  // the server, then updates are streamed as if the client had called
+  // [WaitExecution][build.bazel.remote.execution.v2.Execution.WaitExecution]
+  // until the execution completes or the request reaches an error. The
+  // operation can also be queried using [Operations
+  // API][google.longrunning.Operations.GetOperation].
+  //
+  // The server NEED NOT implement other methods or functionality of the
+  // Operations API.
+  //
+  // Errors discovered during creation of the `Operation` will be reported
+  // as gRPC Status errors, while errors that occurred while running the
+  // action will be reported in the `status` field of the `ExecuteResponse`. The
+  // server MUST NOT set the `error` field of the `Operation` proto.
+  // The possible errors include:
+  // * `INVALID_ARGUMENT`: One or more arguments are invalid.
+  // * `FAILED_PRECONDITION`: One or more errors occurred in setting up the
+  //   action requested, such as a missing input or command or no worker being
+  //   available. The client may be able to fix the errors and retry.
+  // * `RESOURCE_EXHAUSTED`: There is insufficient quota of some resource to run
+  //   the action.
+  // * `UNAVAILABLE`: Due to a transient condition, such as all workers being
+  //   occupied (and the server does not support a queue), the action could not
+  //   be started. The client should retry.
+  // * `INTERNAL`: An internal error occurred in the execution engine or the
+  //   worker.
+  // * `DEADLINE_EXCEEDED`: The execution timed out.
+  //
+  // In the case of a missing input or command, the server SHOULD additionally
+  // send a [PreconditionFailure][google.rpc.PreconditionFailure] error detail
+  // where, for each requested blob not present in the CAS, there is a
+  // `Violation` with a `type` of `MISSING` and a `subject` of
+  // `"blobs/{hash}/{size}"` indicating the digest of the missing blob.
+  rpc Execute(ExecuteRequest) returns (stream google.longrunning.Operation) {
+    option (google.api.http) = { post: "/v2/{instance_name=**}/actions:execute" body: "*" };
+  }
+
+  // Wait for an execution operation to complete. When the client initially
+  // makes the request, the server immediately responds with the current status
+  // of the execution. The server will leave the request stream open until the
+  // operation completes, and then respond with the completed operation. The
+  // server MAY choose to stream additional updates as execution progresses,
+  // such as to provide an update as to the state of the execution.
+  rpc WaitExecution(WaitExecutionRequest) returns (stream google.longrunning.Operation) {
+    option (google.api.http) = { post: "/v2/{name=operations/**}:waitExecution" body: "*" };
+  }
+}
+
+// The action cache API is used to query whether a given action has already been
+// performed and, if so, retrieve its result. Unlike the
+// [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage],
+// which addresses blobs by their own content, the action cache addresses the
+// [ActionResult][build.bazel.remote.execution.v2.ActionResult] by a
+// digest of the encoded [Action][build.bazel.remote.execution.v2.Action]
+// which produced them.
+//
+// The lifetime of entries in the action cache is implementation-specific, but
+// the server SHOULD assume that more recently used entries are more likely to
+// be used again. Additionally, action cache implementations SHOULD ensure that
+// any blobs referenced in the
+// [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage]
+// are still valid when returning a result.
+//
+// As with other services in the Remote Execution API, any call may return an
+// error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+// information about when the client should retry the request; clients SHOULD
+// respect the information provided.
+service ActionCache {
+  // Retrieve a cached execution result.
+  //
+  // Errors:
+  // * `NOT_FOUND`: The requested `ActionResult` is not in the cache.
+  rpc GetActionResult(GetActionResultRequest) returns (ActionResult) {
+    option (google.api.http) = { get: "/v2/{instance_name=**}/actionResults/{action_digest.hash}/{action_digest.size_bytes}" };
+  }
+
+  // Upload a new execution result.
+  //
+  // This method is intended for servers which implement the distributed cache
+  // independently of the
+  // [Execution][build.bazel.remote.execution.v2.Execution] API. As a
+  // result, it is OPTIONAL for servers to implement.
+  //
+  // In order to allow the server to perform access control based on the type of
+  // action, and to assist with client debugging, the client MUST first upload
+  // the [Action][build.bazel.remote.execution.v2.Execution] that produced the
+  // result, along with its
+  // [Command][build.bazel.remote.execution.v2.Command], into the
+  // `ContentAddressableStorage`.
+  //
+  // Errors:
+  // * `NOT_IMPLEMENTED`: This method is not supported by the server.
+  // * `RESOURCE_EXHAUSTED`: There is insufficient storage space to add the
+  //   entry to the cache.
+  rpc UpdateActionResult(UpdateActionResultRequest) returns (ActionResult) {
+    option (google.api.http) = { put: "/v2/{instance_name=**}/actionResults/{action_digest.hash}/{action_digest.size_bytes}" body: "action_result" };
+  }
+}
+
+// The CAS (content-addressable storage) is used to store the inputs to and
+// outputs from the execution service. Each piece of content is addressed by the
+// digest of its binary data.
+//
+// Most of the binary data stored in the CAS is opaque to the execution engine,
+// and is only used as a communication medium. In order to build an
+// [Action][build.bazel.remote.execution.v2.Action],
+// however, the client will need to also upload the
+// [Command][build.bazel.remote.execution.v2.Command] and input root
+// [Directory][build.bazel.remote.execution.v2.Directory] for the Action.
+// The Command and Directory messages must be marshalled to wire format and then
+// uploaded under the hash as with any other piece of content. In practice, the
+// input root directory is likely to refer to other Directories in its
+// hierarchy, which must also each be uploaded on their own.
+//
+// For small file uploads the client should group them together and call
+// [BatchUpdateBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchUpdateBlobs]
+// on chunks of no more than 10 MiB. For large uploads, the client must use the
+// [Write method][google.bytestream.ByteStream.Write] of the ByteStream API. The
+// `resource_name` is `{instance_name}/uploads/{uuid}/blobs/{hash}/{size}`,
+// where `instance_name` is as described in the next paragraph, `uuid` is a
+// version 4 UUID generated by the client, and `hash` and `size` are the
+// [Digest][build.bazel.remote.execution.v2.Digest] of the blob. The
+// `uuid` is used only to avoid collisions when multiple clients try to upload
+// the same file (or the same client tries to upload the file multiple times at
+// once on different threads), so the client MAY reuse the `uuid` for uploading
+// different blobs. The `resource_name` may optionally have a trailing filename
+// (or other metadata) for a client to use if it is storing URLs, as in
+// `{instance}/uploads/{uuid}/blobs/{hash}/{size}/foo/bar/baz.cc`. Anything
+// after the `size` is ignored.
+//
+// A single server MAY support multiple instances of the execution system, each
+// with their own workers, storage, cache, etc. The exact relationship between
+// instances is up to the server. If the server does, then the `instance_name`
+// is an identifier, possibly containing multiple path segments, used to
+// distinguish between the various instances on the server, in a manner defined
+// by the server. For servers which do not support multiple instances, then the
+// `instance_name` is the empty path and the leading slash is omitted, so that
+// the `resource_name` becomes `uploads/{uuid}/blobs/{hash}/{size}`.
+//
+// When attempting an upload, if another client has already completed the upload
+// (which may occur in the middle of a single upload if another client uploads
+// the same blob concurrently), the request will terminate immediately with
+// a response whose `committed_size` is the full size of the uploaded file
+// (regardless of how much data was transmitted by the client). If the client
+// completes the upload but the
+// [Digest][build.bazel.remote.execution.v2.Digest] does not match, an
+// `INVALID_ARGUMENT` error will be returned. In either case, the client should
+// not attempt to retry the upload.
+//
+// For downloading blobs, the client must use the
+// [Read method][google.bytestream.ByteStream.Read] of the ByteStream API, with
+// a `resource_name` of `"{instance_name}/blobs/{hash}/{size}"`, where
+// `instance_name` is the instance name (see above), and `hash` and `size` are
+// the [Digest][build.bazel.remote.execution.v2.Digest] of the blob.
+//
+// The lifetime of entries in the CAS is implementation specific, but it SHOULD
+// be long enough to allow for newly-added and recently looked-up entries to be
+// used in subsequent calls (e.g. to
+// [Execute][build.bazel.remote.execution.v2.Execution.Execute]).
+//
+// As with other services in the Remote Execution API, any call may return an
+// error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+// information about when the client should retry the request; clients SHOULD
+// respect the information provided.
+service ContentAddressableStorage {
+  // Determine if blobs are present in the CAS.
+  //
+  // Clients can use this API before uploading blobs to determine which ones are
+  // already present in the CAS and do not need to be uploaded again.
+  //
+  // There are no method-specific errors.
+  rpc FindMissingBlobs(FindMissingBlobsRequest) returns (FindMissingBlobsResponse) {
+    option (google.api.http) = { post: "/v2/{instance_name=**}/blobs:findMissing" body: "*" };
+  }
+
+  // Upload many blobs at once.
+  //
+  // The server may enforce a limit of the combined total size of blobs
+  // to be uploaded using this API. This limit may be obtained using the
+  // [Capabilities][build.bazel.remote.execution.v2.Capabilities] API.
+  // Requests exceeding the limit should either be split into smaller
+  // chunks or uploaded using the
+  // [ByteStream API][google.bytestream.ByteStream], as appropriate.
+  //
+  // This request is equivalent to calling a Bytestream `Write` request
+  // on each individual blob, in parallel. The requests may succeed or fail
+  // independently.
+  //
+  // Errors:
+  // * `INVALID_ARGUMENT`: The client attempted to upload more than the
+  //   server supported limit.
+  //
+  // Individual requests may return the following errors, additionally:
+  // * `RESOURCE_EXHAUSTED`: There is insufficient disk quota to store the blob.
+  // * `INVALID_ARGUMENT`: The
+  // [Digest][build.bazel.remote.execution.v2.Digest] does not match the
+  // provided data.
+  rpc BatchUpdateBlobs(BatchUpdateBlobsRequest) returns (BatchUpdateBlobsResponse) {
+    option (google.api.http) = { post: "/v2/{instance_name=**}/blobs:batchUpdate" body: "*" };
+  }
+
+  // Download many blobs at once.
+  //
+  // The server may enforce a limit of the combined total size of blobs
+  // to be downloaded using this API. This limit may be obtained using the
+  // [Capabilities][build.bazel.remote.execution.v2.Capabilities] API.
+  // Requests exceeding the limit should either be split into smaller
+  // chunks or downloaded using the
+  // [ByteStream API][google.bytestream.ByteStream], as appropriate.
+  //
+  // This request is equivalent to calling a Bytestream `Read` request
+  // on each individual blob, in parallel. The requests may succeed or fail
+  // independently.
+  //
+  // Errors:
+  // * `INVALID_ARGUMENT`: The client attempted to read more than the
+  //   server supported limit.
+  //
+  // Every error on individual read will be returned in the corresponding digest
+  // status.
+  rpc BatchReadBlobs(BatchReadBlobsRequest) returns (BatchReadBlobsResponse) {
+    option (google.api.http) = { post: "/v2/{instance_name=**}/blobs:batchRead" body: "*" };
+  }
+
+  // Fetch the entire directory tree rooted at a node.
+  //
+  // This request must be targeted at a
+  // [Directory][build.bazel.remote.execution.v2.Directory] stored in the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage]
+  // (CAS). The server will enumerate the `Directory` tree recursively and
+  // return every node descended from the root.
+  //
+  // The GetTreeRequest.page_token parameter can be used to skip ahead in
+  // the stream (e.g. when retrying a partially completed and aborted request),
+  // by setting it to a value taken from GetTreeResponse.next_page_token of the
+  // last successfully processed GetTreeResponse).
+  //
+  // The exact traversal order is unspecified and, unless retrieving subsequent
+  // pages from an earlier request, is not guaranteed to be stable across
+  // multiple invocations of `GetTree`.
+  //
+  // If part of the tree is missing from the CAS, the server will return the
+  // portion present and omit the rest.
+  //
+  // * `NOT_FOUND`: The requested tree root is not present in the CAS.
+  rpc GetTree(GetTreeRequest) returns (stream GetTreeResponse) {
+    option (google.api.http) = { get: "/v2/{instance_name=**}/blobs/{root_digest.hash}/{root_digest.size_bytes}:getTree" };
+  }
+}
+
+// The Capabilities service may be used by remote execution clients to query
+// various server properties, in order to self-configure or return meaningful
+// error messages.
+//
+// The query may include a particular `instance_name`, in which case the values
+// returned will pertain to that instance.
+service Capabilities {
+  // GetCapabilities returns the server capabilities configuration.
+  rpc GetCapabilities(GetCapabilitiesRequest) returns (ServerCapabilities) {
+    option (google.api.http) = {
+      get: "/v2/{instance_name=**}/capabilities"
+    };
+  }
+}
+
+// An `Action` captures all the information about an execution which is required
+// to reproduce it.
+//
+// `Action`s are the core component of the [Execution] service. A single
+// `Action` represents a repeatable action that can be performed by the
+// execution service. `Action`s can be succinctly identified by the digest of
+// their wire format encoding and, once an `Action` has been executed, will be
+// cached in the action cache. Future requests can then use the cached result
+// rather than needing to run afresh.
+//
+// When a server completes execution of an
+// [Action][build.bazel.remote.execution.v2.Action], it MAY choose to
+// cache the [result][build.bazel.remote.execution.v2.ActionResult] in
+// the [ActionCache][build.bazel.remote.execution.v2.ActionCache] unless
+// `do_not_cache` is `true`. Clients SHOULD expect the server to do so. By
+// default, future calls to
+// [Execute][build.bazel.remote.execution.v2.Execution.Execute] the same
+// `Action` will also serve their results from the cache. Clients must take care
+// to understand the caching behaviour. Ideally, all `Action`s will be
+// reproducible so that serving a result from cache is always desirable and
+// correct.
+message Action {
+  // The digest of the [Command][build.bazel.remote.execution.v2.Command]
+  // to run, which MUST be present in the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+  Digest command_digest = 1;
+
+  // The digest of the root
+  // [Directory][build.bazel.remote.execution.v2.Directory] for the input
+  // files. The files in the directory tree are available in the correct
+  // location on the build machine before the command is executed. The root
+  // directory, as well as every subdirectory and content blob referred to, MUST
+  // be in the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+  Digest input_root_digest = 2;
+
+  reserved 3 to 5; // Used for fields moved to [Command][build.bazel.remote.execution.v2.Command].
+
+  // A timeout after which the execution should be killed. If the timeout is
+  // absent, then the client is specifying that the execution should continue
+  // as long as the server will let it. The server SHOULD impose a timeout if
+  // the client does not specify one, however, if the client does specify a
+  // timeout that is longer than the server's maximum timeout, the server MUST
+  // reject the request.
+  //
+  // The timeout is a part of the
+  // [Action][build.bazel.remote.execution.v2.Action] message, and
+  // therefore two `Actions` with different timeouts are different, even if they
+  // are otherwise identical. This is because, if they were not, running an
+  // `Action` with a lower timeout than is required might result in a cache hit
+  // from an execution run with a longer timeout, hiding the fact that the
+  // timeout is too short. By encoding it directly in the `Action`, a lower
+  // timeout will result in a cache miss and the execution timeout will fail
+  // immediately, rather than whenever the cache entry gets evicted.
+  google.protobuf.Duration timeout = 6;
+
+  // If true, then the `Action`'s result cannot be cached.
+  bool do_not_cache = 7;
+}
+
+// A `Command` is the actual command executed by a worker running an
+// [Action][build.bazel.remote.execution.v2.Action] and specifications of its
+// environment.
+//
+// Except as otherwise required, the environment (such as which system
+// libraries or binaries are available, and what filesystems are mounted where)
+// is defined by and specific to the implementation of the remote execution API.
+message Command {
+  // An `EnvironmentVariable` is one variable to set in the running program's
+  // environment.
+  message EnvironmentVariable {
+    // The variable name.
+    string name = 1;
+
+    // The variable value.
+    string value = 2;
+  }
+
+  // The arguments to the command. The first argument must be the path to the
+  // executable, which must be either a relative path, in which case it is
+  // evaluated with respect to the input root, or an absolute path.
+  repeated string arguments = 1;
+
+  // The environment variables to set when running the program. The worker may
+  // provide its own default environment variables; these defaults can be
+  // overridden using this field. Additional variables can also be specified.
+  //
+  // In order to ensure that equivalent `Command`s always hash to the same
+  // value, the environment variables MUST be lexicographically sorted by name.
+  // Sorting of strings is done by code point, equivalently, by the UTF-8 bytes.
+  repeated EnvironmentVariable environment_variables = 2;
+
+  // A list of the output files that the client expects to retrieve from the
+  // action. Only the listed files, as well as directories listed in
+  // `output_directories`, will be returned to the client as output.
+  // Other files that may be created during command execution are discarded.
+  //
+  // The paths are relative to the working directory of the action execution.
+  // The paths are specified using a single forward slash (`/`) as a path
+  // separator, even if the execution platform natively uses a different
+  // separator. The path MUST NOT include a trailing slash, nor a leading slash,
+  // being a relative path.
+  //
+  // In order to ensure consistent hashing of the same Action, the output paths
+  // MUST be sorted lexicographically by code point (or, equivalently, by UTF-8
+  // bytes).
+  //
+  // An output file cannot be duplicated, be a parent of another output file, be
+  // a child of a listed output directory, or have the same path as any of the
+  // listed output directories.
+  repeated string output_files = 3;
+
+  // A list of the output directories that the client expects to retrieve from
+  // the action. Only the contents of the indicated directories (recursively
+  // including the contents of their subdirectories) will be
+  // returned, as well as files listed in `output_files`. Other files that may
+  // be created during command execution are discarded.
+  //
+  // The paths are relative to the working directory of the action execution.
+  // The paths are specified using a single forward slash (`/`) as a path
+  // separator, even if the execution platform natively uses a different
+  // separator. The path MUST NOT include a trailing slash, nor a leading slash,
+  // being a relative path. The special value of empty string is allowed,
+  // although not recommended, and can be used to capture the entire working
+  // directory tree, including inputs.
+  //
+  // In order to ensure consistent hashing of the same Action, the output paths
+  // MUST be sorted lexicographically by code point (or, equivalently, by UTF-8
+  // bytes).
+  //
+  // An output directory cannot be duplicated, be a parent of another output
+  // directory, be a parent of a listed output file, or have the same path as
+  // any of the listed output files.
+  repeated string output_directories = 4;
+
+  // The platform requirements for the execution environment. The server MAY
+  // choose to execute the action on any worker satisfying the requirements, so
+  // the client SHOULD ensure that running the action on any such worker will
+  // have the same result.
+  Platform platform = 5;
+
+  // The working directory, relative to the input root, for the command to run
+  // in. It must be a directory which exists in the input tree. If it is left
+  // empty, then the action is run in the input root.
+  string working_directory = 6;
+}
+
+// A `Platform` is a set of requirements, such as hardware, operating system, or
+// compiler toolchain, for an
+// [Action][build.bazel.remote.execution.v2.Action]'s execution
+// environment. A `Platform` is represented as a series of key-value pairs
+// representing the properties that are required of the platform.
+message Platform {
+  // A single property for the environment. The server is responsible for
+  // specifying the property `name`s that it accepts. If an unknown `name` is
+  // provided in the requirements for an
+  // [Action][build.bazel.remote.execution.v2.Action], the server SHOULD
+  // reject the execution request. If permitted by the server, the same `name`
+  // may occur multiple times.
+  //
+  // The server is also responsible for specifying the interpretation of
+  // property `value`s. For instance, a property describing how much RAM must be
+  // available may be interpreted as allowing a worker with 16GB to fulfill a
+  // request for 8GB, while a property describing the OS environment on which
+  // the action must be performed may require an exact match with the worker's
+  // OS.
+  //
+  // The server MAY use the `value` of one or more properties to determine how
+  // it sets up the execution environment, such as by making specific system
+  // files available to the worker.
+  message Property {
+    // The property name.
+    string name = 1;
+
+    // The property value.
+    string value = 2;
+  }
+
+  // The properties that make up this platform. In order to ensure that
+  // equivalent `Platform`s always hash to the same value, the properties MUST
+  // be lexicographically sorted by name, and then by value. Sorting of strings
+  // is done by code point, equivalently, by the UTF-8 bytes.
+  repeated Property properties = 1;
+}
+
+// A `Directory` represents a directory node in a file tree, containing zero or
+// more children [FileNodes][build.bazel.remote.execution.v2.FileNode],
+// [DirectoryNodes][build.bazel.remote.execution.v2.DirectoryNode] and
+// [SymlinkNodes][build.bazel.remote.execution.v2.SymlinkNode].
+// Each `Node` contains its name in the directory, either the digest of its
+// content (either a file blob or a `Directory` proto) or a symlink target, as
+// well as possibly some metadata about the file or directory.
+//
+// In order to ensure that two equivalent directory trees hash to the same
+// value, the following restrictions MUST be obeyed when constructing a
+// a `Directory`:
+//   - Every child in the directory must have a path of exactly one segment.
+//     Multiple levels of directory hierarchy may not be collapsed.
+//   - Each child in the directory must have a unique path segment (file name).
+//   - The files, directories and symlinks in the directory must each be sorted
+//     in lexicographical order by path. The path strings must be sorted by code
+//     point, equivalently, by UTF-8 bytes.
+//
+// A `Directory` that obeys the restrictions is said to be in canonical form.
+//
+// As an example, the following could be used for a file named `bar` and a
+// directory named `foo` with an executable file named `baz` (hashes shortened
+// for readability):
+//
+// ```json
+// // (Directory proto)
+// {
+//   files: [
+//     {
+//       name: "bar",
+//       digest: {
+//         hash: "4a73bc9d03...",
+//         size: 65534
+//       }
+//     }
+//   ],
+//   directories: [
+//     {
+//       name: "foo",
+//       digest: {
+//         hash: "4cf2eda940...",
+//         size: 43
+//       }
+//     }
+//   ]
+// }
+//
+// // (Directory proto with hash "4cf2eda940..." and size 43)
+// {
+//   files: [
+//     {
+//       name: "baz",
+//       digest: {
+//         hash: "b2c941073e...",
+//         size: 1294,
+//       },
+//       is_executable: true
+//     }
+//   ]
+// }
+// ```
+message Directory {
+  // The files in the directory.
+  repeated FileNode files = 1;
+
+  // The subdirectories in the directory.
+  repeated DirectoryNode directories = 2;
+
+  // The symlinks in the directory.
+  repeated SymlinkNode symlinks = 3;
+}
+
+// A `FileNode` represents a single file and associated metadata.
+message FileNode {
+  // The name of the file.
+  string name = 1;
+
+  // The digest of the file's content.
+  Digest digest = 2;
+
+  reserved 3; // Reserved to ensure wire-compatibility with `OutputFile`.
+
+  // True if file is executable, false otherwise.
+  bool is_executable = 4;
+}
+
+// A `DirectoryNode` represents a child of a
+// [Directory][build.bazel.remote.execution.v2.Directory] which is itself
+// a `Directory` and its associated metadata.
+message DirectoryNode {
+  // The name of the directory.
+  string name = 1;
+
+  // The digest of the
+  // [Directory][build.bazel.remote.execution.v2.Directory] object
+  // represented. See [Digest][build.bazel.remote.execution.v2.Digest]
+  // for information about how to take the digest of a proto message.
+  Digest digest = 2;
+}
+
+// A `SymlinkNode` represents a symbolic link.
+message SymlinkNode {
+  // The name of the symlink.
+  string name = 1;
+
+  // The target path of the symlink. The path separator is a forward slash `/`.
+  // The target path can be relative to the parent directory of the symlink or
+  // it can be an absolute path starting with `/`. Support for absolute paths
+  // can be checked using the [Capabilities][build.bazel.remote.execution.v2.Capabilities]
+  // API. The canonical form forbids the substrings `/./` and `//` in the target
+  // path. `..` components are allowed anywhere in the target path.
+  string target = 2;
+}
+
+// A content digest. A digest for a given blob consists of the size of the blob
+// and its hash. The hash algorithm to use is defined by the server, but servers
+// SHOULD use SHA-256.
+//
+// The size is considered to be an integral part of the digest and cannot be
+// separated. That is, even if the `hash` field is correctly specified but
+// `size_bytes` is not, the server MUST reject the request.
+//
+// The reason for including the size in the digest is as follows: in a great
+// many cases, the server needs to know the size of the blob it is about to work
+// with prior to starting an operation with it, such as flattening Merkle tree
+// structures or streaming it to a worker. Technically, the server could
+// implement a separate metadata store, but this results in a significantly more
+// complicated implementation as opposed to having the client specify the size
+// up-front (or storing the size along with the digest in every message where
+// digests are embedded). This does mean that the API leaks some implementation
+// details of (what we consider to be) a reasonable server implementation, but
+// we consider this to be a worthwhile tradeoff.
+//
+// When a `Digest` is used to refer to a proto message, it always refers to the
+// message in binary encoded form. To ensure consistent hashing, clients and
+// servers MUST ensure that they serialize messages according to the following
+// rules, even if there are alternate valid encodings for the same message.
+// - Fields are serialized in tag order.
+// - There are no unknown fields.
+// - There are no duplicate fields.
+// - Fields are serialized according to the default semantics for their type.
+//
+// Most protocol buffer implementations will always follow these rules when
+// serializing, but care should be taken to avoid shortcuts. For instance,
+// concatenating two messages to merge them may produce duplicate fields.
+message Digest {
+  // The hash. In the case of SHA-256, it will always be a lowercase hex string
+  // exactly 64 characters long.
+  string hash = 1;
+
+  // The size of the blob, in bytes.
+  int64 size_bytes = 2;
+}
+
+// ExecutedActionMetadata contains details about a completed execution.
+message ExecutedActionMetadata {
+  // The name of the worker which ran the execution.
+  string worker = 1;
+
+  // When was the action added to the queue.
+  google.protobuf.Timestamp queued_timestamp = 2;
+
+  // When the worker received the action.
+  google.protobuf.Timestamp worker_start_timestamp = 3;
+
+  // When the worker completed the action, including all stages.
+  google.protobuf.Timestamp worker_completed_timestamp = 4;
+
+  // When the worker started fetching action inputs.
+  google.protobuf.Timestamp input_fetch_start_timestamp = 5;
+
+  // When the worker finished fetching action inputs.
+  google.protobuf.Timestamp input_fetch_completed_timestamp = 6;
+
+  // When the worker started executing the action command.
+  google.protobuf.Timestamp execution_start_timestamp = 7;
+
+  // When the worker completed executing the action command.
+  google.protobuf.Timestamp execution_completed_timestamp = 8;
+
+  // When the worker started uploading action outputs.
+  google.protobuf.Timestamp output_upload_start_timestamp = 9;
+
+  // When the worker finished uploading action outputs.
+  google.protobuf.Timestamp output_upload_completed_timestamp = 10;
+}
+
+// An ActionResult represents the result of an
+// [Action][build.bazel.remote.execution.v2.Action] being run.
+message ActionResult {
+  reserved 1; // Reserved for use as the resource name.
+
+  // The output files of the action. For each output file requested in the
+  // `output_files` field of the Action, if the corresponding file existed after
+  // the action completed, a single entry will be present in the output list.
+  //
+  // If the action does not produce the requested output, or produces a
+  // directory where a regular file is expected or vice versa, then that output
+  // will be omitted from the list. The server is free to arrange the output
+  // list as desired; clients MUST NOT assume that the output list is sorted.
+  repeated OutputFile output_files = 2;
+
+  // The output directories of the action. For each output directory requested
+  // in the `output_directories` field of the Action, if the corresponding
+  // directory existed after the action completed, a single entry will be
+  // present in the output list, which will contain the digest of a
+  // [Tree][build.bazel.remote.execution.v2.Tree] message containing the
+  // directory tree, and the path equal exactly to the corresponding Action
+  // output_directories member.
+  //
+  // As an example, suppose the Action had an output directory `a/b/dir` and the
+  // execution produced the following contents in `a/b/dir`: a file named `bar`
+  // and a directory named `foo` with an executable file named `baz`. Then,
+  // output_directory will contain (hashes shortened for readability):
+  //
+  // ```json
+  // // OutputDirectory proto:
+  // {
+  //   path: "a/b/dir"
+  //   tree_digest: {
+  //     hash: "4a73bc9d03...",
+  //     size: 55
+  //   }
+  // }
+  // // Tree proto with hash "4a73bc9d03..." and size 55:
+  // {
+  //   root: {
+  //     files: [
+  //       {
+  //         name: "bar",
+  //         digest: {
+  //           hash: "4a73bc9d03...",
+  //           size: 65534
+  //         }
+  //       }
+  //     ],
+  //     directories: [
+  //       {
+  //         name: "foo",
+  //         digest: {
+  //           hash: "4cf2eda940...",
+  //           size: 43
+  //         }
+  //       }
+  //     ]
+  //   }
+  //   children : {
+  //     // (Directory proto with hash "4cf2eda940..." and size 43)
+  //     files: [
+  //       {
+  //         name: "baz",
+  //         digest: {
+  //           hash: "b2c941073e...",
+  //           size: 1294,
+  //         },
+  //         is_executable: true
+  //       }
+  //     ]
+  //   }
+  // }
+  // ```
+  repeated OutputDirectory output_directories = 3;
+
+  // The exit code of the command.
+  int32 exit_code = 4;
+
+  // The standard output buffer of the action. The server will determine, based
+  // on the size of the buffer, whether to return it in raw form or to return
+  // a digest in `stdout_digest` that points to the buffer. If neither is set,
+  // then the buffer is empty. The client SHOULD NOT assume it will get one of
+  // the raw buffer or a digest on any given request and should be prepared to
+  // handle either.
+  bytes stdout_raw = 5;
+
+  // The digest for a blob containing the standard output of the action, which
+  // can be retrieved from the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+  // See `stdout_raw` for when this will be set.
+  Digest stdout_digest = 6;
+
+  // The standard error buffer of the action. The server will determine, based
+  // on the size of the buffer, whether to return it in raw form or to return
+  // a digest in `stderr_digest` that points to the buffer. If neither is set,
+  // then the buffer is empty. The client SHOULD NOT assume it will get one of
+  // the raw buffer or a digest on any given request and should be prepared to
+  // handle either.
+  bytes stderr_raw = 7;
+
+  // The digest for a blob containing the standard error of the action, which
+  // can be retrieved from the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+  // See `stderr_raw` for when this will be set.
+  Digest stderr_digest = 8;
+
+  // The details of the execution that originally produced this result.
+  ExecutedActionMetadata execution_metadata = 9;
+}
+
+// An `OutputFile` is similar to a
+// [FileNode][build.bazel.remote.execution.v2.FileNode], but it is used as an
+// output in an `ActionResult`. It allows a full file path rather than
+// only a name.
+//
+// `OutputFile` is binary-compatible with `FileNode`.
+message OutputFile {
+  // The full path of the file relative to the input root, including the
+  // filename. The path separator is a forward slash `/`. Since this is a
+  // relative path, it MUST NOT begin with a leading forward slash.
+  string path = 1;
+
+  // The digest of the file's content.
+  Digest digest = 2;
+
+  reserved 3; // Used for a removed field in an earlier version of the API.
+
+  // True if file is executable, false otherwise.
+  bool is_executable = 4;
+}
+
+// A `Tree` contains all the
+// [Directory][build.bazel.remote.execution.v2.Directory] protos in a
+// single directory Merkle tree, compressed into one message.
+message Tree {
+  // The root directory in the tree.
+  Directory root = 1;
+
+  // All the child directories: the directories referred to by the root and,
+  // recursively, all its children. In order to reconstruct the directory tree,
+  // the client must take the digests of each of the child directories and then
+  // build up a tree starting from the `root`.
+  repeated Directory children = 2;
+}
+
+// An `OutputDirectory` is the output in an `ActionResult` corresponding to a
+// directory's full contents rather than a single file.
+message OutputDirectory {
+  // The full path of the directory relative to the working directory. The path
+  // separator is a forward slash `/`. Since this is a relative path, it MUST
+  // NOT begin with a leading forward slash. The empty string value is allowed,
+  // and it denotes the entire working directory.
+  string path = 1;
+
+  reserved 2; // Used for a removed field in an earlier version of the API.
+
+  // The digest of the encoded
+  // [Tree][build.bazel.remote.execution.v2.Tree] proto containing the
+  // directory's contents.
+  Digest tree_digest = 3;
+}
+
+// An `ExecutionPolicy` can be used to control the scheduling of the action.
+message ExecutionPolicy {
+  // The priority (relative importance) of this action. Generally, a lower value
+  // means that the action should be run sooner than actions having a greater
+  // priority value, but the interpretation of a given value is server-
+  // dependent. A priority of 0 means the *default* priority. Priorities may be
+  // positive or negative, and such actions should run later or sooner than
+  // actions having the default priority, respectively. The particular semantics
+  // of this field is up to the server. In particular, every server will have
+  // their own supported range of priorities, and will decide how these map into
+  // scheduling policy.
+  int32 priority = 1;
+}
+
+// A `ResultsCachePolicy` is used for fine-grained control over how action
+// outputs are stored in the CAS and Action Cache.
+message ResultsCachePolicy {
+  // The priority (relative importance) of this content in the overall cache.
+  // Generally, a lower value means a longer retention time or other advantage,
+  // but the interpretation of a given value is server-dependent. A priority of
+  // 0 means a *default* value, decided by the server.
+  //
+  // The particular semantics of this field is up to the server. In particular,
+  // every server will have their own supported range of priorities, and will
+  // decide how these map into retention/eviction policy.
+  int32 priority = 1;
+}
+
+// A request message for
+// [Execution.Execute][build.bazel.remote.execution.v2.Execution.Execute].
+message ExecuteRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // If true, the action will be executed anew even if its result was already
+  // present in the cache. If false, the result may be served from the
+  // [ActionCache][build.bazel.remote.execution.v2.ActionCache].
+  bool skip_cache_lookup = 3;
+
+  reserved 2, 4, 5; // Used for removed fields in an earlier version of the API.
+
+  // The digest of the [Action][build.bazel.remote.execution.v2.Action] to
+  // execute.
+  Digest action_digest = 6;
+
+  // An optional policy for execution of the action.
+  // The server will have a default policy if this is not provided.
+  ExecutionPolicy execution_policy = 7;
+
+  // An optional policy for the results of this execution in the remote cache.
+  // The server will have a default policy if this is not provided.
+  // This may be applied to both the ActionResult and the associated blobs.
+  ResultsCachePolicy results_cache_policy = 8;
+}
+
+// A `LogFile` is a log stored in the CAS.
+message LogFile {
+  // The digest of the log contents.
+  Digest digest = 1;
+
+  // This is a hint as to the purpose of the log, and is set to true if the log
+  // is human-readable text that can be usefully displayed to a user, and false
+  // otherwise. For instance, if a command-line client wishes to print the
+  // server logs to the terminal for a failed action, this allows it to avoid
+  // displaying a binary file.
+  bool human_readable = 2;
+}
+
+// The response message for
+// [Execution.Execute][build.bazel.remote.execution.v2.Execution.Execute],
+// which will be contained in the [response
+// field][google.longrunning.Operation.response] of the
+// [Operation][google.longrunning.Operation].
+message ExecuteResponse {
+  // The result of the action.
+  ActionResult result = 1;
+
+  // True if the result was served from cache, false if it was executed.
+  bool cached_result = 2;
+
+  // If the status has a code other than `OK`, it indicates that the action did
+  // not finish execution. For example, if the operation times out during
+  // execution, the status will have a `DEADLINE_EXCEEDED` code. Servers MUST
+  // use this field for errors in execution, rather than the error field on the
+  // `Operation` object.
+  //
+  // If the status code is other than `OK`, then the result MUST NOT be cached.
+  // For an error status, the `result` field is optional; the server may
+  // populate the output-, stdout-, and stderr-related fields if it has any
+  // information available, such as the stdout and stderr of a timed-out action.
+  google.rpc.Status status = 3;
+
+  // An optional list of additional log outputs the server wishes to provide. A
+  // server can use this to return execution-specific logs however it wishes.
+  // This is intended primarily to make it easier for users to debug issues that
+  // may be outside of the actual job execution, such as by identifying the
+  // worker executing the action or by providing logs from the worker's setup
+  // phase. The keys SHOULD be human readable so that a client can display them
+  // to a user.
+  map<string, LogFile> server_logs = 4;
+}
+
+// Metadata about an ongoing
+// [execution][build.bazel.remote.execution.v2.Execution.Execute], which
+// will be contained in the [metadata
+// field][google.longrunning.Operation.response] of the
+// [Operation][google.longrunning.Operation].
+message ExecuteOperationMetadata {
+  // The current stage of execution.
+  enum Stage {
+    UNKNOWN = 0;
+
+    // Checking the result against the cache.
+    CACHE_CHECK = 1;
+
+    // Currently idle, awaiting a free machine to execute.
+    QUEUED = 2;
+
+    // Currently being executed by a worker.
+    EXECUTING = 3;
+
+    // Finished execution.
+    COMPLETED = 4;
+  }
+
+  Stage stage = 1;
+
+  // The digest of the [Action][build.bazel.remote.execution.v2.Action]
+  // being executed.
+  Digest action_digest = 2;
+
+  // If set, the client can use this name with
+  // [ByteStream.Read][google.bytestream.ByteStream.Read] to stream the
+  // standard output.
+  string stdout_stream_name = 3;
+
+  // If set, the client can use this name with
+  // [ByteStream.Read][google.bytestream.ByteStream.Read] to stream the
+  // standard error.
+  string stderr_stream_name = 4;
+}
+
+// A request message for
+// [WaitExecution][build.bazel.remote.execution.v2.Execution.WaitExecution].
+message WaitExecutionRequest {
+  // The name of the [Operation][google.longrunning.operations.v1.Operation]
+  // returned by [Execute][build.bazel.remote.execution.v2.Execution.Execute].
+  string name = 1;
+}
+
+// A request message for
+// [ActionCache.GetActionResult][build.bazel.remote.execution.v2.ActionCache.GetActionResult].
+message GetActionResultRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The digest of the [Action][build.bazel.remote.execution.v2.Action]
+  // whose result is requested.
+  Digest action_digest = 2;
+}
+
+// A request message for
+// [ActionCache.UpdateActionResult][build.bazel.remote.execution.v2.ActionCache.UpdateActionResult].
+message UpdateActionResultRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The digest of the [Action][build.bazel.remote.execution.v2.Action]
+  // whose result is being uploaded.
+  Digest action_digest = 2;
+
+  // The [ActionResult][build.bazel.remote.execution.v2.ActionResult]
+  // to store in the cache.
+  ActionResult action_result = 3;
+
+  // An optional policy for the results of this execution in the remote cache.
+  // The server will have a default policy if this is not provided.
+  // This may be applied to both the ActionResult and the associated blobs.
+  ResultsCachePolicy results_cache_policy = 4;
+}
+
+// A request message for
+// [ContentAddressableStorage.FindMissingBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.FindMissingBlobs].
+message FindMissingBlobsRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // A list of the blobs to check.
+  repeated Digest blob_digests = 2;
+}
+
+// A response message for
+// [ContentAddressableStorage.FindMissingBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.FindMissingBlobs].
+message FindMissingBlobsResponse {
+  // A list of the blobs requested *not* present in the storage.
+  repeated Digest missing_blob_digests = 2;
+}
+
+// A request message for
+// [ContentAddressableStorage.BatchUpdateBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchUpdateBlobs].
+message BatchUpdateBlobsRequest {
+  // A request corresponding to a single blob that the client wants to upload.
+  message Request {
+    // The digest of the blob. This MUST be the digest of `data`.
+    Digest digest = 1;
+
+    // The raw binary data.
+    bytes data = 2;
+  }
+
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The individual upload requests.
+  repeated Request requests = 2;
+}
+
+// A response message for
+// [ContentAddressableStorage.BatchUpdateBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchUpdateBlobs].
+message BatchUpdateBlobsResponse {
+  // A response corresponding to a single blob that the client tried to upload.
+  message Response {
+    // The blob digest to which this response corresponds.
+    Digest digest = 1;
+
+    // The result of attempting to upload that blob.
+    google.rpc.Status status = 2;
+  }
+
+  // The responses to the requests.
+  repeated Response responses = 1;
+}
+
+// A request message for
+// [ContentAddressableStorage.BatchReadBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchReadBlobs].
+message BatchReadBlobsRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The individual blob digests.
+  repeated Digest digests = 2;
+}
+
+// A response message for
+// [ContentAddressableStorage.BatchReadBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchReadBlobs].
+message BatchReadBlobsResponse {
+  // A response corresponding to a single blob that the client tried to upload.
+  message Response {
+    // The digest to which this response corresponds.
+    Digest digest = 1;
+
+    // The raw binary data.
+    bytes data = 2;
+
+    // The result of attempting to download that blob.
+    google.rpc.Status status = 3;
+  }
+
+  // The responses to the requests.
+  repeated Response responses = 1;
+}
+
+// A request message for
+// [ContentAddressableStorage.GetTree][build.bazel.remote.execution.v2.ContentAddressableStorage.GetTree].
+message GetTreeRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The digest of the root, which must be an encoded
+  // [Directory][build.bazel.remote.execution.v2.Directory] message
+  // stored in the
+  // [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+  Digest root_digest = 2;
+
+  // A maximum page size to request. If present, the server will request no more
+  // than this many items. Regardless of whether a page size is specified, the
+  // server may place its own limit on the number of items to be returned and
+  // require the client to retrieve more items using a subsequent request.
+  int32 page_size = 3;
+
+  // A page token, which must be a value received in a previous
+  // [GetTreeResponse][build.bazel.remote.execution.v2.GetTreeResponse].
+  // If present, the server will use it to return the following page of results.
+  string page_token = 4;
+}
+
+// A response message for
+// [ContentAddressableStorage.GetTree][build.bazel.remote.execution.v2.ContentAddressableStorage.GetTree].
+message GetTreeResponse {
+  // The directories descended from the requested root.
+  repeated Directory directories = 1;
+
+  // If present, signifies that there are more results which the client can
+  // retrieve by passing this as the page_token in a subsequent
+  // [request][build.bazel.remote.execution.v2.GetTreeRequest].
+  // If empty, signifies that this is the last page of results.
+  string next_page_token = 2;
+}
+
+// A request message for
+// [Capabilities.GetCapabilities][google.devtools.remoteexecution.v2.Capabilities.GetCapabilities].
+message GetCapabilitiesRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+}
+
+// A response message for
+// [Capabilities.GetCapabilities][google.devtools.remoteexecution.v2.Capabilities.GetCapabilities].
+message ServerCapabilities {
+  // Capabilities of the remote cache system.
+  CacheCapabilities cache_capabilities = 1;
+
+  // Capabilities of the remote execution system.
+  ExecutionCapabilities execution_capabilities = 2;
+
+  // Earliest RE API version supported, including deprecated versions.
+  build.bazel.semver.SemVer deprecated_api_version = 3;
+
+  // Earliest non-deprecated RE API version supported.
+  build.bazel.semver.SemVer low_api_version = 4;
+
+  // Latest RE API version supported.
+  build.bazel.semver.SemVer high_api_version = 5;
+}
+
+// The digest function used for converting values into keys for CAS and Action
+// Cache.
+enum DigestFunction {
+  UNKNOWN = 0;
+  SHA256 = 1;
+  SHA1 = 2;
+  MD5 = 3;
+}
+
+// Describes the server/instance capabilities for updating the action cache.
+message ActionCacheUpdateCapabilities {
+  bool update_enabled = 1;
+}
+
+// Allowed values for priority in
+// [ResultsCachePolicy][google.devtools.remoteexecution.v2.ResultsCachePolicy]
+// Used for querying both cache and execution valid priority ranges.
+message PriorityCapabilities {
+  // Supported range of priorities, including boundaries.
+  message PriorityRange {
+    int32 min_priority = 1;
+    int32 max_priority = 2;
+  }
+  repeated PriorityRange priorities = 1;
+}
+
+// Capabilities of the remote cache system.
+message CacheCapabilities {
+  // Describes how the server treats absolute symlink targets.
+  enum SymlinkAbsolutePathStrategy {
+    UNKNOWN = 0;
+
+    // Server will return an INVALID_ARGUMENT on input symlinks with absolute targets.
+    // If an action tries to create an output symlink with an absolute target, a
+    // FAILED_PRECONDITION will be returned.
+    DISALLOWED = 1;
+
+    // Server will allow symlink targets to escape the input root tree, possibly
+    // resulting in non-hermetic builds.
+    ALLOWED = 2;
+  }
+
+  // All the digest functions supported by the remote cache.
+  // Remote cache may support multiple digest functions simultaneously.
+  repeated DigestFunction digest_function = 1;
+
+  // Capabilities for updating the action cache.
+  ActionCacheUpdateCapabilities action_cache_update_capabilities = 2;
+
+  // Supported cache priority range for both CAS and ActionCache.
+  PriorityCapabilities cache_priority_capabilities = 3;
+
+  // Maximum total size of blobs to be uploaded/downloaded using
+  // batch methods. A value of 0 means no limit is set, although
+  // in practice there will always be a message size limitation
+  // of the protocol in use, e.g. GRPC.
+  int64 max_batch_total_size_bytes = 4;
+
+  // Whether absolute symlink targets are supported.
+  SymlinkAbsolutePathStrategy symlink_absolute_path_strategy = 5;
+}
+
+// Capabilities of the remote execution system.
+message ExecutionCapabilities {
+  // Remote execution may only support a single digest function.
+  DigestFunction digest_function = 1;
+
+  // Whether remote execution is enabled for the particular server/instance.
+  bool exec_enabled = 2;
+
+  // Supported execution priority range.
+  PriorityCapabilities execution_priority_capabilities = 3;
+}
+
+// Details for the tool used to call the API.
+message ToolDetails {
+  // Name of the tool, e.g. bazel.
+  string tool_name = 1;
+
+  // Version of the tool used for the request, e.g. 5.0.3.
+  string tool_version = 2;
+}
+
+// An optional Metadata to attach to any RPC request to tell the server about an
+// external context of the request. The server may use this for logging or other
+// purposes. To use it, the client attaches the header to the call using the
+// canonical proto serialization:
+// name: build.bazel.remote.execution.v2.requestmetadata-bin
+// contents: the base64 encoded binary RequestMetadata message.
+message RequestMetadata {
+  // The details for the tool invoking the requests.
+  ToolDetails tool_details = 1;
+
+  // An identifier that ties multiple requests to the same action.
+  // For example, multiple requests to the CAS, Action Cache, and Execution
+  // API are used in order to compile foo.cc.
+  string action_id = 2;
+
+  // An identifier that ties multiple actions together to a final result.
+  // For example, multiple actions are required to build and run foo_test.
+  string tool_invocation_id = 3;
+
+  // An identifier to tie multiple tool invocations together. For example,
+  // runs of foo_test, bar_test and baz_test on a post-submit of a given patch.
+  string correlated_invocations_id = 4;
+}
diff --git a/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution_pb2.py b/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution_pb2.py
new file mode 100644
index 000000000..46d59b184
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution_pb2.py
@@ -0,0 +1,2660 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: build/bazel/remote/execution/v2/remote_execution.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf.internal import enum_type_wrapper
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.build.bazel.semver import semver_pb2 as build_dot_bazel_dot_semver_dot_semver__pb2
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+from buildstream._protos.google.longrunning import operations_pb2 as google_dot_longrunning_dot_operations__pb2
+from google.protobuf import duration_pb2 as google_dot_protobuf_dot_duration__pb2
+from google.protobuf import timestamp_pb2 as google_dot_protobuf_dot_timestamp__pb2
+from buildstream._protos.google.rpc import status_pb2 as google_dot_rpc_dot_status__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='build/bazel/remote/execution/v2/remote_execution.proto',
+  package='build.bazel.remote.execution.v2',
+  syntax='proto3',
+  serialized_pb=_b('\n6build/bazel/remote/execution/v2/remote_execution.proto\x12\x1f\x62uild.bazel.remote.execution.v2\x1a\x1f\x62uild/bazel/semver/semver.proto\x1a\x1cgoogle/api/annotations.proto\x1a#google/longrunning/operations.proto\x1a\x1egoogle/protobuf/duration.proto\x1a\x1fgoogle/protobuf/timestamp.proto\x1a\x17google/rpc/status.proto\"\xd5\x01\n\x06\x41\x63tion\x12?\n\x0e\x63ommand_digest\x18\x01 \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\x12\x42\n\x11input_root_digest\x18\x02 \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\x12*\n\x07timeout\x18\x06 \x01(\x0b\x32\x19.google.protobuf.Duration\x12\x14\n\x0c\x64o_not_cache\x18\x07 \x01(\x08J\x04\x08\x03\x10\x06\"\xb7\x02\n\x07\x43ommand\x12\x11\n\targuments\x18\x01 \x03(\t\x12[\n\x15\x65nvironment_variables\x18\x02 \x03(\x0b\x32<.build.bazel.remote.execution.v2.Command.EnvironmentVariable\x12\x14\n\x0coutput_files\x18\x03 \x03(\t\x12\x1a\n\x12output_directories\x18\x04 \x03(\t\x12;\n\x08platform\x18\x05 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+  ,
+  dependencies=[build_dot_bazel_dot_semver_dot_semver__pb2.DESCRIPTOR,google_dot_api_dot_annotations__pb2.DESCRIPTOR,google_dot_longrunning_dot_operations__pb2.DESCRIPTOR,google_dot_protobuf_dot_duration__pb2.DESCRIPTOR,google_dot_protobuf_dot_timestamp__pb2.DESCRIPTOR,google_dot_rpc_dot_status__pb2.DESCRIPTOR,])
+
+_DIGESTFUNCTION = _descriptor.EnumDescriptor(
+  name='DigestFunction',
+  full_name='build.bazel.remote.execution.v2.DigestFunction',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='UNKNOWN', index=0, number=0,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='SHA256', index=1, number=1,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='SHA1', index=2, number=2,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='MD5', index=3, number=3,
+      options=None,
+      type=None),
+  ],
+  containing_type=None,
+  options=None,
+  serialized_start=7213,
+  serialized_end=7273,
+)
+_sym_db.RegisterEnumDescriptor(_DIGESTFUNCTION)
+
+DigestFunction = enum_type_wrapper.EnumTypeWrapper(_DIGESTFUNCTION)
+UNKNOWN = 0
+SHA256 = 1
+SHA1 = 2
+MD5 = 3
+
+
+_EXECUTEOPERATIONMETADATA_STAGE = _descriptor.EnumDescriptor(
+  name='Stage',
+  full_name='build.bazel.remote.execution.v2.ExecuteOperationMetadata.Stage',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='UNKNOWN', index=0, number=0,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='CACHE_CHECK', index=1, number=1,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='QUEUED', index=2, number=2,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='EXECUTING', index=3, number=3,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='COMPLETED', index=4, number=4,
+      options=None,
+      type=None),
+  ],
+  containing_type=None,
+  options=None,
+  serialized_start=3866,
+  serialized_end=3945,
+)
+_sym_db.RegisterEnumDescriptor(_EXECUTEOPERATIONMETADATA_STAGE)
+
+_CACHECAPABILITIES_SYMLINKABSOLUTEPATHSTRATEGY = _descriptor.EnumDescriptor(
+  name='SymlinkAbsolutePathStrategy',
+  full_name='build.bazel.remote.execution.v2.CacheCapabilities.SymlinkAbsolutePathStrategy',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='UNKNOWN', index=0, number=0,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='DISALLOWED', index=1, number=1,
+      options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='ALLOWED', index=2, number=2,
+      options=None,
+      type=None),
+  ],
+  containing_type=None,
+  options=None,
+  serialized_start=6696,
+  serialized_end=6767,
+)
+_sym_db.RegisterEnumDescriptor(_CACHECAPABILITIES_SYMLINKABSOLUTEPATHSTRATEGY)
+
+
+_ACTION = _descriptor.Descriptor(
+  name='Action',
+  full_name='build.bazel.remote.execution.v2.Action',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='command_digest', full_name='build.bazel.remote.execution.v2.Action.command_digest', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='input_root_digest', full_name='build.bazel.remote.execution.v2.Action.input_root_digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='timeout', full_name='build.bazel.remote.execution.v2.Action.timeout', index=2,
+      number=6, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='do_not_cache', full_name='build.bazel.remote.execution.v2.Action.do_not_cache', index=3,
+      number=7, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=282,
+  serialized_end=495,
+)
+
+
+_COMMAND_ENVIRONMENTVARIABLE = _descriptor.Descriptor(
+  name='EnvironmentVariable',
+  full_name='build.bazel.remote.execution.v2.Command.EnvironmentVariable',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='build.bazel.remote.execution.v2.Command.EnvironmentVariable.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='value', full_name='build.bazel.remote.execution.v2.Command.EnvironmentVariable.value', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=759,
+  serialized_end=809,
+)
+
+_COMMAND = _descriptor.Descriptor(
+  name='Command',
+  full_name='build.bazel.remote.execution.v2.Command',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='arguments', full_name='build.bazel.remote.execution.v2.Command.arguments', index=0,
+      number=1, type=9, cpp_type=9, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='environment_variables', full_name='build.bazel.remote.execution.v2.Command.environment_variables', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='output_files', full_name='build.bazel.remote.execution.v2.Command.output_files', index=2,
+      number=3, type=9, cpp_type=9, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='output_directories', full_name='build.bazel.remote.execution.v2.Command.output_directories', index=3,
+      number=4, type=9, cpp_type=9, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='platform', full_name='build.bazel.remote.execution.v2.Command.platform', index=4,
+      number=5, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='working_directory', full_name='build.bazel.remote.execution.v2.Command.working_directory', index=5,
+      number=6, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_COMMAND_ENVIRONMENTVARIABLE, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=498,
+  serialized_end=809,
+)
+
+
+_PLATFORM_PROPERTY = _descriptor.Descriptor(
+  name='Property',
+  full_name='build.bazel.remote.execution.v2.Platform.Property',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='build.bazel.remote.execution.v2.Platform.Property.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='value', full_name='build.bazel.remote.execution.v2.Platform.Property.value', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=895,
+  serialized_end=934,
+)
+
+_PLATFORM = _descriptor.Descriptor(
+  name='Platform',
+  full_name='build.bazel.remote.execution.v2.Platform',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='properties', full_name='build.bazel.remote.execution.v2.Platform.properties', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_PLATFORM_PROPERTY, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=811,
+  serialized_end=934,
+)
+
+
+_DIRECTORY = _descriptor.Descriptor(
+  name='Directory',
+  full_name='build.bazel.remote.execution.v2.Directory',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='files', full_name='build.bazel.remote.execution.v2.Directory.files', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='directories', full_name='build.bazel.remote.execution.v2.Directory.directories', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='symlinks', full_name='build.bazel.remote.execution.v2.Directory.symlinks', index=2,
+      number=3, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=937,
+  serialized_end=1139,
+)
+
+
+_FILENODE = _descriptor.Descriptor(
+  name='FileNode',
+  full_name='build.bazel.remote.execution.v2.FileNode',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='build.bazel.remote.execution.v2.FileNode.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.FileNode.digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='is_executable', full_name='build.bazel.remote.execution.v2.FileNode.is_executable', index=2,
+      number=4, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=1141,
+  serialized_end=1251,
+)
+
+
+_DIRECTORYNODE = _descriptor.Descriptor(
+  name='DirectoryNode',
+  full_name='build.bazel.remote.execution.v2.DirectoryNode',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='build.bazel.remote.execution.v2.DirectoryNode.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.DirectoryNode.digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=1253,
+  serialized_end=1339,
+)
+
+
+_SYMLINKNODE = _descriptor.Descriptor(
+  name='SymlinkNode',
+  full_name='build.bazel.remote.execution.v2.SymlinkNode',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='build.bazel.remote.execution.v2.SymlinkNode.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='target', full_name='build.bazel.remote.execution.v2.SymlinkNode.target', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=1341,
+  serialized_end=1384,
+)
+
+
+_DIGEST = _descriptor.Descriptor(
+  name='Digest',
+  full_name='build.bazel.remote.execution.v2.Digest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='hash', full_name='build.bazel.remote.execution.v2.Digest.hash', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='size_bytes', full_name='build.bazel.remote.execution.v2.Digest.size_bytes', index=1,
+      number=2, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=1386,
+  serialized_end=1428,
+)
+
+
+_EXECUTEDACTIONMETADATA = _descriptor.Descriptor(
+  name='ExecutedActionMetadata',
+  full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='worker', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.worker', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='queued_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.queued_timestamp', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='worker_start_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.worker_start_timestamp', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='worker_completed_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.worker_completed_timestamp', index=3,
+      number=4, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='input_fetch_start_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.input_fetch_start_timestamp', index=4,
+      number=5, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='input_fetch_completed_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.input_fetch_completed_timestamp', index=5,
+      number=6, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='execution_start_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.execution_start_timestamp', index=6,
+      number=7, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='execution_completed_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.execution_completed_timestamp', index=7,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='output_upload_start_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.output_upload_start_timestamp', index=8,
+      number=9, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='output_upload_completed_timestamp', full_name='build.bazel.remote.execution.v2.ExecutedActionMetadata.output_upload_completed_timestamp', index=9,
+      number=10, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=1431,
+  serialized_end=2051,
+)
+
+
+_ACTIONRESULT = _descriptor.Descriptor(
+  name='ActionResult',
+  full_name='build.bazel.remote.execution.v2.ActionResult',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='output_files', full_name='build.bazel.remote.execution.v2.ActionResult.output_files', index=0,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='output_directories', full_name='build.bazel.remote.execution.v2.ActionResult.output_directories', index=1,
+      number=3, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='exit_code', full_name='build.bazel.remote.execution.v2.ActionResult.exit_code', index=2,
+      number=4, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='stdout_raw', full_name='build.bazel.remote.execution.v2.ActionResult.stdout_raw', index=3,
+      number=5, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='stdout_digest', full_name='build.bazel.remote.execution.v2.ActionResult.stdout_digest', index=4,
+      number=6, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='stderr_raw', full_name='build.bazel.remote.execution.v2.ActionResult.stderr_raw', index=5,
+      number=7, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='stderr_digest', full_name='build.bazel.remote.execution.v2.ActionResult.stderr_digest', index=6,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='execution_metadata', full_name='build.bazel.remote.execution.v2.ActionResult.execution_metadata', index=7,
+      number=9, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2054,
+  serialized_end=2491,
+)
+
+
+_OUTPUTFILE = _descriptor.Descriptor(
+  name='OutputFile',
+  full_name='build.bazel.remote.execution.v2.OutputFile',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='path', full_name='build.bazel.remote.execution.v2.OutputFile.path', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.OutputFile.digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='is_executable', full_name='build.bazel.remote.execution.v2.OutputFile.is_executable', index=2,
+      number=4, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2493,
+  serialized_end=2605,
+)
+
+
+_TREE = _descriptor.Descriptor(
+  name='Tree',
+  full_name='build.bazel.remote.execution.v2.Tree',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='root', full_name='build.bazel.remote.execution.v2.Tree.root', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='children', full_name='build.bazel.remote.execution.v2.Tree.children', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2607,
+  serialized_end=2733,
+)
+
+
+_OUTPUTDIRECTORY = _descriptor.Descriptor(
+  name='OutputDirectory',
+  full_name='build.bazel.remote.execution.v2.OutputDirectory',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='path', full_name='build.bazel.remote.execution.v2.OutputDirectory.path', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='tree_digest', full_name='build.bazel.remote.execution.v2.OutputDirectory.tree_digest', index=1,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2735,
+  serialized_end=2834,
+)
+
+
+_EXECUTIONPOLICY = _descriptor.Descriptor(
+  name='ExecutionPolicy',
+  full_name='build.bazel.remote.execution.v2.ExecutionPolicy',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='priority', full_name='build.bazel.remote.execution.v2.ExecutionPolicy.priority', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2836,
+  serialized_end=2871,
+)
+
+
+_RESULTSCACHEPOLICY = _descriptor.Descriptor(
+  name='ResultsCachePolicy',
+  full_name='build.bazel.remote.execution.v2.ResultsCachePolicy',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='priority', full_name='build.bazel.remote.execution.v2.ResultsCachePolicy.priority', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2873,
+  serialized_end=2911,
+)
+
+
+_EXECUTEREQUEST = _descriptor.Descriptor(
+  name='ExecuteRequest',
+  full_name='build.bazel.remote.execution.v2.ExecuteRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.ExecuteRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='skip_cache_lookup', full_name='build.bazel.remote.execution.v2.ExecuteRequest.skip_cache_lookup', index=1,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_digest', full_name='build.bazel.remote.execution.v2.ExecuteRequest.action_digest', index=2,
+      number=6, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='execution_policy', full_name='build.bazel.remote.execution.v2.ExecuteRequest.execution_policy', index=3,
+      number=7, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='results_cache_policy', full_name='build.bazel.remote.execution.v2.ExecuteRequest.results_cache_policy', index=4,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=2914,
+  serialized_end=3221,
+)
+
+
+_LOGFILE = _descriptor.Descriptor(
+  name='LogFile',
+  full_name='build.bazel.remote.execution.v2.LogFile',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.LogFile.digest', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='human_readable', full_name='build.bazel.remote.execution.v2.LogFile.human_readable', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=3223,
+  serialized_end=3313,
+)
+
+
+_EXECUTERESPONSE_SERVERLOGSENTRY = _descriptor.Descriptor(
+  name='ServerLogsEntry',
+  full_name='build.bazel.remote.execution.v2.ExecuteResponse.ServerLogsEntry',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='key', full_name='build.bazel.remote.execution.v2.ExecuteResponse.ServerLogsEntry.key', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='value', full_name='build.bazel.remote.execution.v2.ExecuteResponse.ServerLogsEntry.value', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=_descriptor._ParseOptions(descriptor_pb2.MessageOptions(), _b('8\001')),
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=3544,
+  serialized_end=3635,
+)
+
+_EXECUTERESPONSE = _descriptor.Descriptor(
+  name='ExecuteResponse',
+  full_name='build.bazel.remote.execution.v2.ExecuteResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='result', full_name='build.bazel.remote.execution.v2.ExecuteResponse.result', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='cached_result', full_name='build.bazel.remote.execution.v2.ExecuteResponse.cached_result', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='status', full_name='build.bazel.remote.execution.v2.ExecuteResponse.status', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='server_logs', full_name='build.bazel.remote.execution.v2.ExecuteResponse.server_logs', index=3,
+      number=4, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_EXECUTERESPONSE_SERVERLOGSENTRY, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=3316,
+  serialized_end=3635,
+)
+
+
+_EXECUTEOPERATIONMETADATA = _descriptor.Descriptor(
+  name='ExecuteOperationMetadata',
+  full_name='build.bazel.remote.execution.v2.ExecuteOperationMetadata',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='stage', full_name='build.bazel.remote.execution.v2.ExecuteOperationMetadata.stage', index=0,
+      number=1, type=14, cpp_type=8, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_digest', full_name='build.bazel.remote.execution.v2.ExecuteOperationMetadata.action_digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='stdout_stream_name', full_name='build.bazel.remote.execution.v2.ExecuteOperationMetadata.stdout_stream_name', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='stderr_stream_name', full_name='build.bazel.remote.execution.v2.ExecuteOperationMetadata.stderr_stream_name', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+    _EXECUTEOPERATIONMETADATA_STAGE,
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=3638,
+  serialized_end=3945,
+)
+
+
+_WAITEXECUTIONREQUEST = _descriptor.Descriptor(
+  name='WaitExecutionRequest',
+  full_name='build.bazel.remote.execution.v2.WaitExecutionRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='build.bazel.remote.execution.v2.WaitExecutionRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=3947,
+  serialized_end=3983,
+)
+
+
+_GETACTIONRESULTREQUEST = _descriptor.Descriptor(
+  name='GetActionResultRequest',
+  full_name='build.bazel.remote.execution.v2.GetActionResultRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.GetActionResultRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_digest', full_name='build.bazel.remote.execution.v2.GetActionResultRequest.action_digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=3985,
+  serialized_end=4096,
+)
+
+
+_UPDATEACTIONRESULTREQUEST = _descriptor.Descriptor(
+  name='UpdateActionResultRequest',
+  full_name='build.bazel.remote.execution.v2.UpdateActionResultRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.UpdateActionResultRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_digest', full_name='build.bazel.remote.execution.v2.UpdateActionResultRequest.action_digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_result', full_name='build.bazel.remote.execution.v2.UpdateActionResultRequest.action_result', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='results_cache_policy', full_name='build.bazel.remote.execution.v2.UpdateActionResultRequest.results_cache_policy', index=3,
+      number=4, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4099,
+  serialized_end=4366,
+)
+
+
+_FINDMISSINGBLOBSREQUEST = _descriptor.Descriptor(
+  name='FindMissingBlobsRequest',
+  full_name='build.bazel.remote.execution.v2.FindMissingBlobsRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.FindMissingBlobsRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='blob_digests', full_name='build.bazel.remote.execution.v2.FindMissingBlobsRequest.blob_digests', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4368,
+  serialized_end=4479,
+)
+
+
+_FINDMISSINGBLOBSRESPONSE = _descriptor.Descriptor(
+  name='FindMissingBlobsResponse',
+  full_name='build.bazel.remote.execution.v2.FindMissingBlobsResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='missing_blob_digests', full_name='build.bazel.remote.execution.v2.FindMissingBlobsResponse.missing_blob_digests', index=0,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4481,
+  serialized_end=4578,
+)
+
+
+_BATCHUPDATEBLOBSREQUEST_REQUEST = _descriptor.Descriptor(
+  name='Request',
+  full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsRequest.Request',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsRequest.Request.digest', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='data', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsRequest.Request.data', index=1,
+      number=2, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4715,
+  serialized_end=4795,
+)
+
+_BATCHUPDATEBLOBSREQUEST = _descriptor.Descriptor(
+  name='BatchUpdateBlobsRequest',
+  full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='requests', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsRequest.requests', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_BATCHUPDATEBLOBSREQUEST_REQUEST, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4581,
+  serialized_end=4795,
+)
+
+
+_BATCHUPDATEBLOBSRESPONSE_RESPONSE = _descriptor.Descriptor(
+  name='Response',
+  full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsResponse.Response',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsResponse.Response.digest', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='status', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsResponse.Response.status', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4913,
+  serialized_end=5016,
+)
+
+_BATCHUPDATEBLOBSRESPONSE = _descriptor.Descriptor(
+  name='BatchUpdateBlobsResponse',
+  full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='responses', full_name='build.bazel.remote.execution.v2.BatchUpdateBlobsResponse.responses', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_BATCHUPDATEBLOBSRESPONSE_RESPONSE, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=4798,
+  serialized_end=5016,
+)
+
+
+_BATCHREADBLOBSREQUEST = _descriptor.Descriptor(
+  name='BatchReadBlobsRequest',
+  full_name='build.bazel.remote.execution.v2.BatchReadBlobsRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.BatchReadBlobsRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='digests', full_name='build.bazel.remote.execution.v2.BatchReadBlobsRequest.digests', index=1,
+      number=2, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5018,
+  serialized_end=5122,
+)
+
+
+_BATCHREADBLOBSRESPONSE_RESPONSE = _descriptor.Descriptor(
+  name='Response',
+  full_name='build.bazel.remote.execution.v2.BatchReadBlobsResponse.Response',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='build.bazel.remote.execution.v2.BatchReadBlobsResponse.Response.digest', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='data', full_name='build.bazel.remote.execution.v2.BatchReadBlobsResponse.Response.data', index=1,
+      number=2, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='status', full_name='build.bazel.remote.execution.v2.BatchReadBlobsResponse.Response.status', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5236,
+  serialized_end=5353,
+)
+
+_BATCHREADBLOBSRESPONSE = _descriptor.Descriptor(
+  name='BatchReadBlobsResponse',
+  full_name='build.bazel.remote.execution.v2.BatchReadBlobsResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='responses', full_name='build.bazel.remote.execution.v2.BatchReadBlobsResponse.responses', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_BATCHREADBLOBSRESPONSE_RESPONSE, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5125,
+  serialized_end=5353,
+)
+
+
+_GETTREEREQUEST = _descriptor.Descriptor(
+  name='GetTreeRequest',
+  full_name='build.bazel.remote.execution.v2.GetTreeRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.GetTreeRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='root_digest', full_name='build.bazel.remote.execution.v2.GetTreeRequest.root_digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='page_size', full_name='build.bazel.remote.execution.v2.GetTreeRequest.page_size', index=2,
+      number=3, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='page_token', full_name='build.bazel.remote.execution.v2.GetTreeRequest.page_token', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5356,
+  serialized_end=5496,
+)
+
+
+_GETTREERESPONSE = _descriptor.Descriptor(
+  name='GetTreeResponse',
+  full_name='build.bazel.remote.execution.v2.GetTreeResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='directories', full_name='build.bazel.remote.execution.v2.GetTreeResponse.directories', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='next_page_token', full_name='build.bazel.remote.execution.v2.GetTreeResponse.next_page_token', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5498,
+  serialized_end=5605,
+)
+
+
+_GETCAPABILITIESREQUEST = _descriptor.Descriptor(
+  name='GetCapabilitiesRequest',
+  full_name='build.bazel.remote.execution.v2.GetCapabilitiesRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='build.bazel.remote.execution.v2.GetCapabilitiesRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5607,
+  serialized_end=5654,
+)
+
+
+_SERVERCAPABILITIES = _descriptor.Descriptor(
+  name='ServerCapabilities',
+  full_name='build.bazel.remote.execution.v2.ServerCapabilities',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='cache_capabilities', full_name='build.bazel.remote.execution.v2.ServerCapabilities.cache_capabilities', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='execution_capabilities', full_name='build.bazel.remote.execution.v2.ServerCapabilities.execution_capabilities', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='deprecated_api_version', full_name='build.bazel.remote.execution.v2.ServerCapabilities.deprecated_api_version', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='low_api_version', full_name='build.bazel.remote.execution.v2.ServerCapabilities.low_api_version', index=3,
+      number=4, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='high_api_version', full_name='build.bazel.remote.execution.v2.ServerCapabilities.high_api_version', index=4,
+      number=5, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=5657,
+  serialized_end=6012,
+)
+
+
+_ACTIONCACHEUPDATECAPABILITIES = _descriptor.Descriptor(
+  name='ActionCacheUpdateCapabilities',
+  full_name='build.bazel.remote.execution.v2.ActionCacheUpdateCapabilities',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='update_enabled', full_name='build.bazel.remote.execution.v2.ActionCacheUpdateCapabilities.update_enabled', index=0,
+      number=1, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=6014,
+  serialized_end=6069,
+)
+
+
+_PRIORITYCAPABILITIES_PRIORITYRANGE = _descriptor.Descriptor(
+  name='PriorityRange',
+  full_name='build.bazel.remote.execution.v2.PriorityCapabilities.PriorityRange',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='min_priority', full_name='build.bazel.remote.execution.v2.PriorityCapabilities.PriorityRange.min_priority', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='max_priority', full_name='build.bazel.remote.execution.v2.PriorityCapabilities.PriorityRange.max_priority', index=1,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=6185,
+  serialized_end=6244,
+)
+
+_PRIORITYCAPABILITIES = _descriptor.Descriptor(
+  name='PriorityCapabilities',
+  full_name='build.bazel.remote.execution.v2.PriorityCapabilities',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='priorities', full_name='build.bazel.remote.execution.v2.PriorityCapabilities.priorities', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_PRIORITYCAPABILITIES_PRIORITYRANGE, ],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=6072,
+  serialized_end=6244,
+)
+
+
+_CACHECAPABILITIES = _descriptor.Descriptor(
+  name='CacheCapabilities',
+  full_name='build.bazel.remote.execution.v2.CacheCapabilities',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest_function', full_name='build.bazel.remote.execution.v2.CacheCapabilities.digest_function', index=0,
+      number=1, type=14, cpp_type=8, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_cache_update_capabilities', full_name='build.bazel.remote.execution.v2.CacheCapabilities.action_cache_update_capabilities', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='cache_priority_capabilities', full_name='build.bazel.remote.execution.v2.CacheCapabilities.cache_priority_capabilities', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='max_batch_total_size_bytes', full_name='build.bazel.remote.execution.v2.CacheCapabilities.max_batch_total_size_bytes', index=3,
+      number=4, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='symlink_absolute_path_strategy', full_name='build.bazel.remote.execution.v2.CacheCapabilities.symlink_absolute_path_strategy', index=4,
+      number=5, type=14, cpp_type=8, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+    _CACHECAPABILITIES_SYMLINKABSOLUTEPATHSTRATEGY,
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=6247,
+  serialized_end=6767,
+)
+
+
+_EXECUTIONCAPABILITIES = _descriptor.Descriptor(
+  name='ExecutionCapabilities',
+  full_name='build.bazel.remote.execution.v2.ExecutionCapabilities',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest_function', full_name='build.bazel.remote.execution.v2.ExecutionCapabilities.digest_function', index=0,
+      number=1, type=14, cpp_type=8, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='exec_enabled', full_name='build.bazel.remote.execution.v2.ExecutionCapabilities.exec_enabled', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='execution_priority_capabilities', full_name='build.bazel.remote.execution.v2.ExecutionCapabilities.execution_priority_capabilities', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=6770,
+  serialized_end=6985,
+)
+
+
+_TOOLDETAILS = _descriptor.Descriptor(
+  name='ToolDetails',
+  full_name='build.bazel.remote.execution.v2.ToolDetails',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='tool_name', full_name='build.bazel.remote.execution.v2.ToolDetails.tool_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='tool_version', full_name='build.bazel.remote.execution.v2.ToolDetails.tool_version', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=6987,
+  serialized_end=7041,
+)
+
+
+_REQUESTMETADATA = _descriptor.Descriptor(
+  name='RequestMetadata',
+  full_name='build.bazel.remote.execution.v2.RequestMetadata',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='tool_details', full_name='build.bazel.remote.execution.v2.RequestMetadata.tool_details', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='action_id', full_name='build.bazel.remote.execution.v2.RequestMetadata.action_id', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='tool_invocation_id', full_name='build.bazel.remote.execution.v2.RequestMetadata.tool_invocation_id', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='correlated_invocations_id', full_name='build.bazel.remote.execution.v2.RequestMetadata.correlated_invocations_id', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=7044,
+  serialized_end=7211,
+)
+
+_ACTION.fields_by_name['command_digest'].message_type = _DIGEST
+_ACTION.fields_by_name['input_root_digest'].message_type = _DIGEST
+_ACTION.fields_by_name['timeout'].message_type = google_dot_protobuf_dot_duration__pb2._DURATION
+_COMMAND_ENVIRONMENTVARIABLE.containing_type = _COMMAND
+_COMMAND.fields_by_name['environment_variables'].message_type = _COMMAND_ENVIRONMENTVARIABLE
+_COMMAND.fields_by_name['platform'].message_type = _PLATFORM
+_PLATFORM_PROPERTY.containing_type = _PLATFORM
+_PLATFORM.fields_by_name['properties'].message_type = _PLATFORM_PROPERTY
+_DIRECTORY.fields_by_name['files'].message_type = _FILENODE
+_DIRECTORY.fields_by_name['directories'].message_type = _DIRECTORYNODE
+_DIRECTORY.fields_by_name['symlinks'].message_type = _SYMLINKNODE
+_FILENODE.fields_by_name['digest'].message_type = _DIGEST
+_DIRECTORYNODE.fields_by_name['digest'].message_type = _DIGEST
+_EXECUTEDACTIONMETADATA.fields_by_name['queued_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['worker_start_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['worker_completed_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['input_fetch_start_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['input_fetch_completed_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['execution_start_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['execution_completed_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['output_upload_start_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_EXECUTEDACTIONMETADATA.fields_by_name['output_upload_completed_timestamp'].message_type = google_dot_protobuf_dot_timestamp__pb2._TIMESTAMP
+_ACTIONRESULT.fields_by_name['output_files'].message_type = _OUTPUTFILE
+_ACTIONRESULT.fields_by_name['output_directories'].message_type = _OUTPUTDIRECTORY
+_ACTIONRESULT.fields_by_name['stdout_digest'].message_type = _DIGEST
+_ACTIONRESULT.fields_by_name['stderr_digest'].message_type = _DIGEST
+_ACTIONRESULT.fields_by_name['execution_metadata'].message_type = _EXECUTEDACTIONMETADATA
+_OUTPUTFILE.fields_by_name['digest'].message_type = _DIGEST
+_TREE.fields_by_name['root'].message_type = _DIRECTORY
+_TREE.fields_by_name['children'].message_type = _DIRECTORY
+_OUTPUTDIRECTORY.fields_by_name['tree_digest'].message_type = _DIGEST
+_EXECUTEREQUEST.fields_by_name['action_digest'].message_type = _DIGEST
+_EXECUTEREQUEST.fields_by_name['execution_policy'].message_type = _EXECUTIONPOLICY
+_EXECUTEREQUEST.fields_by_name['results_cache_policy'].message_type = _RESULTSCACHEPOLICY
+_LOGFILE.fields_by_name['digest'].message_type = _DIGEST
+_EXECUTERESPONSE_SERVERLOGSENTRY.fields_by_name['value'].message_type = _LOGFILE
+_EXECUTERESPONSE_SERVERLOGSENTRY.containing_type = _EXECUTERESPONSE
+_EXECUTERESPONSE.fields_by_name['result'].message_type = _ACTIONRESULT
+_EXECUTERESPONSE.fields_by_name['status'].message_type = google_dot_rpc_dot_status__pb2._STATUS
+_EXECUTERESPONSE.fields_by_name['server_logs'].message_type = _EXECUTERESPONSE_SERVERLOGSENTRY
+_EXECUTEOPERATIONMETADATA.fields_by_name['stage'].enum_type = _EXECUTEOPERATIONMETADATA_STAGE
+_EXECUTEOPERATIONMETADATA.fields_by_name['action_digest'].message_type = _DIGEST
+_EXECUTEOPERATIONMETADATA_STAGE.containing_type = _EXECUTEOPERATIONMETADATA
+_GETACTIONRESULTREQUEST.fields_by_name['action_digest'].message_type = _DIGEST
+_UPDATEACTIONRESULTREQUEST.fields_by_name['action_digest'].message_type = _DIGEST
+_UPDATEACTIONRESULTREQUEST.fields_by_name['action_result'].message_type = _ACTIONRESULT
+_UPDATEACTIONRESULTREQUEST.fields_by_name['results_cache_policy'].message_type = _RESULTSCACHEPOLICY
+_FINDMISSINGBLOBSREQUEST.fields_by_name['blob_digests'].message_type = _DIGEST
+_FINDMISSINGBLOBSRESPONSE.fields_by_name['missing_blob_digests'].message_type = _DIGEST
+_BATCHUPDATEBLOBSREQUEST_REQUEST.fields_by_name['digest'].message_type = _DIGEST
+_BATCHUPDATEBLOBSREQUEST_REQUEST.containing_type = _BATCHUPDATEBLOBSREQUEST
+_BATCHUPDATEBLOBSREQUEST.fields_by_name['requests'].message_type = _BATCHUPDATEBLOBSREQUEST_REQUEST
+_BATCHUPDATEBLOBSRESPONSE_RESPONSE.fields_by_name['digest'].message_type = _DIGEST
+_BATCHUPDATEBLOBSRESPONSE_RESPONSE.fields_by_name['status'].message_type = google_dot_rpc_dot_status__pb2._STATUS
+_BATCHUPDATEBLOBSRESPONSE_RESPONSE.containing_type = _BATCHUPDATEBLOBSRESPONSE
+_BATCHUPDATEBLOBSRESPONSE.fields_by_name['responses'].message_type = _BATCHUPDATEBLOBSRESPONSE_RESPONSE
+_BATCHREADBLOBSREQUEST.fields_by_name['digests'].message_type = _DIGEST
+_BATCHREADBLOBSRESPONSE_RESPONSE.fields_by_name['digest'].message_type = _DIGEST
+_BATCHREADBLOBSRESPONSE_RESPONSE.fields_by_name['status'].message_type = google_dot_rpc_dot_status__pb2._STATUS
+_BATCHREADBLOBSRESPONSE_RESPONSE.containing_type = _BATCHREADBLOBSRESPONSE
+_BATCHREADBLOBSRESPONSE.fields_by_name['responses'].message_type = _BATCHREADBLOBSRESPONSE_RESPONSE
+_GETTREEREQUEST.fields_by_name['root_digest'].message_type = _DIGEST
+_GETTREERESPONSE.fields_by_name['directories'].message_type = _DIRECTORY
+_SERVERCAPABILITIES.fields_by_name['cache_capabilities'].message_type = _CACHECAPABILITIES
+_SERVERCAPABILITIES.fields_by_name['execution_capabilities'].message_type = _EXECUTIONCAPABILITIES
+_SERVERCAPABILITIES.fields_by_name['deprecated_api_version'].message_type = build_dot_bazel_dot_semver_dot_semver__pb2._SEMVER
+_SERVERCAPABILITIES.fields_by_name['low_api_version'].message_type = build_dot_bazel_dot_semver_dot_semver__pb2._SEMVER
+_SERVERCAPABILITIES.fields_by_name['high_api_version'].message_type = build_dot_bazel_dot_semver_dot_semver__pb2._SEMVER
+_PRIORITYCAPABILITIES_PRIORITYRANGE.containing_type = _PRIORITYCAPABILITIES
+_PRIORITYCAPABILITIES.fields_by_name['priorities'].message_type = _PRIORITYCAPABILITIES_PRIORITYRANGE
+_CACHECAPABILITIES.fields_by_name['digest_function'].enum_type = _DIGESTFUNCTION
+_CACHECAPABILITIES.fields_by_name['action_cache_update_capabilities'].message_type = _ACTIONCACHEUPDATECAPABILITIES
+_CACHECAPABILITIES.fields_by_name['cache_priority_capabilities'].message_type = _PRIORITYCAPABILITIES
+_CACHECAPABILITIES.fields_by_name['symlink_absolute_path_strategy'].enum_type = _CACHECAPABILITIES_SYMLINKABSOLUTEPATHSTRATEGY
+_CACHECAPABILITIES_SYMLINKABSOLUTEPATHSTRATEGY.containing_type = _CACHECAPABILITIES
+_EXECUTIONCAPABILITIES.fields_by_name['digest_function'].enum_type = _DIGESTFUNCTION
+_EXECUTIONCAPABILITIES.fields_by_name['execution_priority_capabilities'].message_type = _PRIORITYCAPABILITIES
+_REQUESTMETADATA.fields_by_name['tool_details'].message_type = _TOOLDETAILS
+DESCRIPTOR.message_types_by_name['Action'] = _ACTION
+DESCRIPTOR.message_types_by_name['Command'] = _COMMAND
+DESCRIPTOR.message_types_by_name['Platform'] = _PLATFORM
+DESCRIPTOR.message_types_by_name['Directory'] = _DIRECTORY
+DESCRIPTOR.message_types_by_name['FileNode'] = _FILENODE
+DESCRIPTOR.message_types_by_name['DirectoryNode'] = _DIRECTORYNODE
+DESCRIPTOR.message_types_by_name['SymlinkNode'] = _SYMLINKNODE
+DESCRIPTOR.message_types_by_name['Digest'] = _DIGEST
+DESCRIPTOR.message_types_by_name['ExecutedActionMetadata'] = _EXECUTEDACTIONMETADATA
+DESCRIPTOR.message_types_by_name['ActionResult'] = _ACTIONRESULT
+DESCRIPTOR.message_types_by_name['OutputFile'] = _OUTPUTFILE
+DESCRIPTOR.message_types_by_name['Tree'] = _TREE
+DESCRIPTOR.message_types_by_name['OutputDirectory'] = _OUTPUTDIRECTORY
+DESCRIPTOR.message_types_by_name['ExecutionPolicy'] = _EXECUTIONPOLICY
+DESCRIPTOR.message_types_by_name['ResultsCachePolicy'] = _RESULTSCACHEPOLICY
+DESCRIPTOR.message_types_by_name['ExecuteRequest'] = _EXECUTEREQUEST
+DESCRIPTOR.message_types_by_name['LogFile'] = _LOGFILE
+DESCRIPTOR.message_types_by_name['ExecuteResponse'] = _EXECUTERESPONSE
+DESCRIPTOR.message_types_by_name['ExecuteOperationMetadata'] = _EXECUTEOPERATIONMETADATA
+DESCRIPTOR.message_types_by_name['WaitExecutionRequest'] = _WAITEXECUTIONREQUEST
+DESCRIPTOR.message_types_by_name['GetActionResultRequest'] = _GETACTIONRESULTREQUEST
+DESCRIPTOR.message_types_by_name['UpdateActionResultRequest'] = _UPDATEACTIONRESULTREQUEST
+DESCRIPTOR.message_types_by_name['FindMissingBlobsRequest'] = _FINDMISSINGBLOBSREQUEST
+DESCRIPTOR.message_types_by_name['FindMissingBlobsResponse'] = _FINDMISSINGBLOBSRESPONSE
+DESCRIPTOR.message_types_by_name['BatchUpdateBlobsRequest'] = _BATCHUPDATEBLOBSREQUEST
+DESCRIPTOR.message_types_by_name['BatchUpdateBlobsResponse'] = _BATCHUPDATEBLOBSRESPONSE
+DESCRIPTOR.message_types_by_name['BatchReadBlobsRequest'] = _BATCHREADBLOBSREQUEST
+DESCRIPTOR.message_types_by_name['BatchReadBlobsResponse'] = _BATCHREADBLOBSRESPONSE
+DESCRIPTOR.message_types_by_name['GetTreeRequest'] = _GETTREEREQUEST
+DESCRIPTOR.message_types_by_name['GetTreeResponse'] = _GETTREERESPONSE
+DESCRIPTOR.message_types_by_name['GetCapabilitiesRequest'] = _GETCAPABILITIESREQUEST
+DESCRIPTOR.message_types_by_name['ServerCapabilities'] = _SERVERCAPABILITIES
+DESCRIPTOR.message_types_by_name['ActionCacheUpdateCapabilities'] = _ACTIONCACHEUPDATECAPABILITIES
+DESCRIPTOR.message_types_by_name['PriorityCapabilities'] = _PRIORITYCAPABILITIES
+DESCRIPTOR.message_types_by_name['CacheCapabilities'] = _CACHECAPABILITIES
+DESCRIPTOR.message_types_by_name['ExecutionCapabilities'] = _EXECUTIONCAPABILITIES
+DESCRIPTOR.message_types_by_name['ToolDetails'] = _TOOLDETAILS
+DESCRIPTOR.message_types_by_name['RequestMetadata'] = _REQUESTMETADATA
+DESCRIPTOR.enum_types_by_name['DigestFunction'] = _DIGESTFUNCTION
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Action = _reflection.GeneratedProtocolMessageType('Action', (_message.Message,), dict(
+  DESCRIPTOR = _ACTION,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Action)
+  ))
+_sym_db.RegisterMessage(Action)
+
+Command = _reflection.GeneratedProtocolMessageType('Command', (_message.Message,), dict(
+
+  EnvironmentVariable = _reflection.GeneratedProtocolMessageType('EnvironmentVariable', (_message.Message,), dict(
+    DESCRIPTOR = _COMMAND_ENVIRONMENTVARIABLE,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Command.EnvironmentVariable)
+    ))
+  ,
+  DESCRIPTOR = _COMMAND,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Command)
+  ))
+_sym_db.RegisterMessage(Command)
+_sym_db.RegisterMessage(Command.EnvironmentVariable)
+
+Platform = _reflection.GeneratedProtocolMessageType('Platform', (_message.Message,), dict(
+
+  Property = _reflection.GeneratedProtocolMessageType('Property', (_message.Message,), dict(
+    DESCRIPTOR = _PLATFORM_PROPERTY,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Platform.Property)
+    ))
+  ,
+  DESCRIPTOR = _PLATFORM,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Platform)
+  ))
+_sym_db.RegisterMessage(Platform)
+_sym_db.RegisterMessage(Platform.Property)
+
+Directory = _reflection.GeneratedProtocolMessageType('Directory', (_message.Message,), dict(
+  DESCRIPTOR = _DIRECTORY,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Directory)
+  ))
+_sym_db.RegisterMessage(Directory)
+
+FileNode = _reflection.GeneratedProtocolMessageType('FileNode', (_message.Message,), dict(
+  DESCRIPTOR = _FILENODE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.FileNode)
+  ))
+_sym_db.RegisterMessage(FileNode)
+
+DirectoryNode = _reflection.GeneratedProtocolMessageType('DirectoryNode', (_message.Message,), dict(
+  DESCRIPTOR = _DIRECTORYNODE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.DirectoryNode)
+  ))
+_sym_db.RegisterMessage(DirectoryNode)
+
+SymlinkNode = _reflection.GeneratedProtocolMessageType('SymlinkNode', (_message.Message,), dict(
+  DESCRIPTOR = _SYMLINKNODE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.SymlinkNode)
+  ))
+_sym_db.RegisterMessage(SymlinkNode)
+
+Digest = _reflection.GeneratedProtocolMessageType('Digest', (_message.Message,), dict(
+  DESCRIPTOR = _DIGEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Digest)
+  ))
+_sym_db.RegisterMessage(Digest)
+
+ExecutedActionMetadata = _reflection.GeneratedProtocolMessageType('ExecutedActionMetadata', (_message.Message,), dict(
+  DESCRIPTOR = _EXECUTEDACTIONMETADATA,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecutedActionMetadata)
+  ))
+_sym_db.RegisterMessage(ExecutedActionMetadata)
+
+ActionResult = _reflection.GeneratedProtocolMessageType('ActionResult', (_message.Message,), dict(
+  DESCRIPTOR = _ACTIONRESULT,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ActionResult)
+  ))
+_sym_db.RegisterMessage(ActionResult)
+
+OutputFile = _reflection.GeneratedProtocolMessageType('OutputFile', (_message.Message,), dict(
+  DESCRIPTOR = _OUTPUTFILE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.OutputFile)
+  ))
+_sym_db.RegisterMessage(OutputFile)
+
+Tree = _reflection.GeneratedProtocolMessageType('Tree', (_message.Message,), dict(
+  DESCRIPTOR = _TREE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.Tree)
+  ))
+_sym_db.RegisterMessage(Tree)
+
+OutputDirectory = _reflection.GeneratedProtocolMessageType('OutputDirectory', (_message.Message,), dict(
+  DESCRIPTOR = _OUTPUTDIRECTORY,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.OutputDirectory)
+  ))
+_sym_db.RegisterMessage(OutputDirectory)
+
+ExecutionPolicy = _reflection.GeneratedProtocolMessageType('ExecutionPolicy', (_message.Message,), dict(
+  DESCRIPTOR = _EXECUTIONPOLICY,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecutionPolicy)
+  ))
+_sym_db.RegisterMessage(ExecutionPolicy)
+
+ResultsCachePolicy = _reflection.GeneratedProtocolMessageType('ResultsCachePolicy', (_message.Message,), dict(
+  DESCRIPTOR = _RESULTSCACHEPOLICY,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ResultsCachePolicy)
+  ))
+_sym_db.RegisterMessage(ResultsCachePolicy)
+
+ExecuteRequest = _reflection.GeneratedProtocolMessageType('ExecuteRequest', (_message.Message,), dict(
+  DESCRIPTOR = _EXECUTEREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecuteRequest)
+  ))
+_sym_db.RegisterMessage(ExecuteRequest)
+
+LogFile = _reflection.GeneratedProtocolMessageType('LogFile', (_message.Message,), dict(
+  DESCRIPTOR = _LOGFILE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.LogFile)
+  ))
+_sym_db.RegisterMessage(LogFile)
+
+ExecuteResponse = _reflection.GeneratedProtocolMessageType('ExecuteResponse', (_message.Message,), dict(
+
+  ServerLogsEntry = _reflection.GeneratedProtocolMessageType('ServerLogsEntry', (_message.Message,), dict(
+    DESCRIPTOR = _EXECUTERESPONSE_SERVERLOGSENTRY,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecuteResponse.ServerLogsEntry)
+    ))
+  ,
+  DESCRIPTOR = _EXECUTERESPONSE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecuteResponse)
+  ))
+_sym_db.RegisterMessage(ExecuteResponse)
+_sym_db.RegisterMessage(ExecuteResponse.ServerLogsEntry)
+
+ExecuteOperationMetadata = _reflection.GeneratedProtocolMessageType('ExecuteOperationMetadata', (_message.Message,), dict(
+  DESCRIPTOR = _EXECUTEOPERATIONMETADATA,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecuteOperationMetadata)
+  ))
+_sym_db.RegisterMessage(ExecuteOperationMetadata)
+
+WaitExecutionRequest = _reflection.GeneratedProtocolMessageType('WaitExecutionRequest', (_message.Message,), dict(
+  DESCRIPTOR = _WAITEXECUTIONREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.WaitExecutionRequest)
+  ))
+_sym_db.RegisterMessage(WaitExecutionRequest)
+
+GetActionResultRequest = _reflection.GeneratedProtocolMessageType('GetActionResultRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETACTIONRESULTREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.GetActionResultRequest)
+  ))
+_sym_db.RegisterMessage(GetActionResultRequest)
+
+UpdateActionResultRequest = _reflection.GeneratedProtocolMessageType('UpdateActionResultRequest', (_message.Message,), dict(
+  DESCRIPTOR = _UPDATEACTIONRESULTREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.UpdateActionResultRequest)
+  ))
+_sym_db.RegisterMessage(UpdateActionResultRequest)
+
+FindMissingBlobsRequest = _reflection.GeneratedProtocolMessageType('FindMissingBlobsRequest', (_message.Message,), dict(
+  DESCRIPTOR = _FINDMISSINGBLOBSREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.FindMissingBlobsRequest)
+  ))
+_sym_db.RegisterMessage(FindMissingBlobsRequest)
+
+FindMissingBlobsResponse = _reflection.GeneratedProtocolMessageType('FindMissingBlobsResponse', (_message.Message,), dict(
+  DESCRIPTOR = _FINDMISSINGBLOBSRESPONSE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.FindMissingBlobsResponse)
+  ))
+_sym_db.RegisterMessage(FindMissingBlobsResponse)
+
+BatchUpdateBlobsRequest = _reflection.GeneratedProtocolMessageType('BatchUpdateBlobsRequest', (_message.Message,), dict(
+
+  Request = _reflection.GeneratedProtocolMessageType('Request', (_message.Message,), dict(
+    DESCRIPTOR = _BATCHUPDATEBLOBSREQUEST_REQUEST,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchUpdateBlobsRequest.Request)
+    ))
+  ,
+  DESCRIPTOR = _BATCHUPDATEBLOBSREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchUpdateBlobsRequest)
+  ))
+_sym_db.RegisterMessage(BatchUpdateBlobsRequest)
+_sym_db.RegisterMessage(BatchUpdateBlobsRequest.Request)
+
+BatchUpdateBlobsResponse = _reflection.GeneratedProtocolMessageType('BatchUpdateBlobsResponse', (_message.Message,), dict(
+
+  Response = _reflection.GeneratedProtocolMessageType('Response', (_message.Message,), dict(
+    DESCRIPTOR = _BATCHUPDATEBLOBSRESPONSE_RESPONSE,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchUpdateBlobsResponse.Response)
+    ))
+  ,
+  DESCRIPTOR = _BATCHUPDATEBLOBSRESPONSE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchUpdateBlobsResponse)
+  ))
+_sym_db.RegisterMessage(BatchUpdateBlobsResponse)
+_sym_db.RegisterMessage(BatchUpdateBlobsResponse.Response)
+
+BatchReadBlobsRequest = _reflection.GeneratedProtocolMessageType('BatchReadBlobsRequest', (_message.Message,), dict(
+  DESCRIPTOR = _BATCHREADBLOBSREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchReadBlobsRequest)
+  ))
+_sym_db.RegisterMessage(BatchReadBlobsRequest)
+
+BatchReadBlobsResponse = _reflection.GeneratedProtocolMessageType('BatchReadBlobsResponse', (_message.Message,), dict(
+
+  Response = _reflection.GeneratedProtocolMessageType('Response', (_message.Message,), dict(
+    DESCRIPTOR = _BATCHREADBLOBSRESPONSE_RESPONSE,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchReadBlobsResponse.Response)
+    ))
+  ,
+  DESCRIPTOR = _BATCHREADBLOBSRESPONSE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.BatchReadBlobsResponse)
+  ))
+_sym_db.RegisterMessage(BatchReadBlobsResponse)
+_sym_db.RegisterMessage(BatchReadBlobsResponse.Response)
+
+GetTreeRequest = _reflection.GeneratedProtocolMessageType('GetTreeRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETTREEREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.GetTreeRequest)
+  ))
+_sym_db.RegisterMessage(GetTreeRequest)
+
+GetTreeResponse = _reflection.GeneratedProtocolMessageType('GetTreeResponse', (_message.Message,), dict(
+  DESCRIPTOR = _GETTREERESPONSE,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.GetTreeResponse)
+  ))
+_sym_db.RegisterMessage(GetTreeResponse)
+
+GetCapabilitiesRequest = _reflection.GeneratedProtocolMessageType('GetCapabilitiesRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETCAPABILITIESREQUEST,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.GetCapabilitiesRequest)
+  ))
+_sym_db.RegisterMessage(GetCapabilitiesRequest)
+
+ServerCapabilities = _reflection.GeneratedProtocolMessageType('ServerCapabilities', (_message.Message,), dict(
+  DESCRIPTOR = _SERVERCAPABILITIES,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ServerCapabilities)
+  ))
+_sym_db.RegisterMessage(ServerCapabilities)
+
+ActionCacheUpdateCapabilities = _reflection.GeneratedProtocolMessageType('ActionCacheUpdateCapabilities', (_message.Message,), dict(
+  DESCRIPTOR = _ACTIONCACHEUPDATECAPABILITIES,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ActionCacheUpdateCapabilities)
+  ))
+_sym_db.RegisterMessage(ActionCacheUpdateCapabilities)
+
+PriorityCapabilities = _reflection.GeneratedProtocolMessageType('PriorityCapabilities', (_message.Message,), dict(
+
+  PriorityRange = _reflection.GeneratedProtocolMessageType('PriorityRange', (_message.Message,), dict(
+    DESCRIPTOR = _PRIORITYCAPABILITIES_PRIORITYRANGE,
+    __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+    # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.PriorityCapabilities.PriorityRange)
+    ))
+  ,
+  DESCRIPTOR = _PRIORITYCAPABILITIES,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.PriorityCapabilities)
+  ))
+_sym_db.RegisterMessage(PriorityCapabilities)
+_sym_db.RegisterMessage(PriorityCapabilities.PriorityRange)
+
+CacheCapabilities = _reflection.GeneratedProtocolMessageType('CacheCapabilities', (_message.Message,), dict(
+  DESCRIPTOR = _CACHECAPABILITIES,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.CacheCapabilities)
+  ))
+_sym_db.RegisterMessage(CacheCapabilities)
+
+ExecutionCapabilities = _reflection.GeneratedProtocolMessageType('ExecutionCapabilities', (_message.Message,), dict(
+  DESCRIPTOR = _EXECUTIONCAPABILITIES,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ExecutionCapabilities)
+  ))
+_sym_db.RegisterMessage(ExecutionCapabilities)
+
+ToolDetails = _reflection.GeneratedProtocolMessageType('ToolDetails', (_message.Message,), dict(
+  DESCRIPTOR = _TOOLDETAILS,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.ToolDetails)
+  ))
+_sym_db.RegisterMessage(ToolDetails)
+
+RequestMetadata = _reflection.GeneratedProtocolMessageType('RequestMetadata', (_message.Message,), dict(
+  DESCRIPTOR = _REQUESTMETADATA,
+  __module__ = 'build.bazel.remote.execution.v2.remote_execution_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.remote.execution.v2.RequestMetadata)
+  ))
+_sym_db.RegisterMessage(RequestMetadata)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\037build.bazel.remote.execution.v2B\024RemoteExecutionProtoP\001Z\017remoteexecution\242\002\003REX\252\002\037Build.Bazel.Remote.Execution.V2'))
+_EXECUTERESPONSE_SERVERLOGSENTRY.has_options = True
+_EXECUTERESPONSE_SERVERLOGSENTRY._options = _descriptor._ParseOptions(descriptor_pb2.MessageOptions(), _b('8\001'))
+
+_EXECUTION = _descriptor.ServiceDescriptor(
+  name='Execution',
+  full_name='build.bazel.remote.execution.v2.Execution',
+  file=DESCRIPTOR,
+  index=0,
+  options=None,
+  serialized_start=7276,
+  serialized_end=7589,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='Execute',
+    full_name='build.bazel.remote.execution.v2.Execution.Execute',
+    index=0,
+    containing_service=None,
+    input_type=_EXECUTEREQUEST,
+    output_type=google_dot_longrunning_dot_operations__pb2._OPERATION,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002+\"&/v2/{instance_name=**}/actions:execute:\001*')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='WaitExecution',
+    full_name='build.bazel.remote.execution.v2.Execution.WaitExecution',
+    index=1,
+    containing_service=None,
+    input_type=_WAITEXECUTIONREQUEST,
+    output_type=google_dot_longrunning_dot_operations__pb2._OPERATION,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002+\"&/v2/{name=operations/**}:waitExecution:\001*')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_EXECUTION)
+
+DESCRIPTOR.services_by_name['Execution'] = _EXECUTION
+
+
+_ACTIONCACHE = _descriptor.ServiceDescriptor(
+  name='ActionCache',
+  full_name='build.bazel.remote.execution.v2.ActionCache',
+  file=DESCRIPTOR,
+  index=1,
+  options=None,
+  serialized_start=7592,
+  serialized_end=8062,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='GetActionResult',
+    full_name='build.bazel.remote.execution.v2.ActionCache.GetActionResult',
+    index=0,
+    containing_service=None,
+    input_type=_GETACTIONRESULTREQUEST,
+    output_type=_ACTIONRESULT,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002V\022T/v2/{instance_name=**}/actionResults/{action_digest.hash}/{action_digest.size_bytes}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='UpdateActionResult',
+    full_name='build.bazel.remote.execution.v2.ActionCache.UpdateActionResult',
+    index=1,
+    containing_service=None,
+    input_type=_UPDATEACTIONRESULTREQUEST,
+    output_type=_ACTIONRESULT,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002e\032T/v2/{instance_name=**}/actionResults/{action_digest.hash}/{action_digest.size_bytes}:\raction_result')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_ACTIONCACHE)
+
+DESCRIPTOR.services_by_name['ActionCache'] = _ACTIONCACHE
+
+
+_CONTENTADDRESSABLESTORAGE = _descriptor.ServiceDescriptor(
+  name='ContentAddressableStorage',
+  full_name='build.bazel.remote.execution.v2.ContentAddressableStorage',
+  file=DESCRIPTOR,
+  index=2,
+  options=None,
+  serialized_start=8065,
+  serialized_end=8860,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='FindMissingBlobs',
+    full_name='build.bazel.remote.execution.v2.ContentAddressableStorage.FindMissingBlobs',
+    index=0,
+    containing_service=None,
+    input_type=_FINDMISSINGBLOBSREQUEST,
+    output_type=_FINDMISSINGBLOBSRESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002-\"(/v2/{instance_name=**}/blobs:findMissing:\001*')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='BatchUpdateBlobs',
+    full_name='build.bazel.remote.execution.v2.ContentAddressableStorage.BatchUpdateBlobs',
+    index=1,
+    containing_service=None,
+    input_type=_BATCHUPDATEBLOBSREQUEST,
+    output_type=_BATCHUPDATEBLOBSRESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002-\"(/v2/{instance_name=**}/blobs:batchUpdate:\001*')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='BatchReadBlobs',
+    full_name='build.bazel.remote.execution.v2.ContentAddressableStorage.BatchReadBlobs',
+    index=2,
+    containing_service=None,
+    input_type=_BATCHREADBLOBSREQUEST,
+    output_type=_BATCHREADBLOBSRESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002+\"&/v2/{instance_name=**}/blobs:batchRead:\001*')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='GetTree',
+    full_name='build.bazel.remote.execution.v2.ContentAddressableStorage.GetTree',
+    index=3,
+    containing_service=None,
+    input_type=_GETTREEREQUEST,
+    output_type=_GETTREERESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002R\022P/v2/{instance_name=**}/blobs/{root_digest.hash}/{root_digest.size_bytes}:getTree')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_CONTENTADDRESSABLESTORAGE)
+
+DESCRIPTOR.services_by_name['ContentAddressableStorage'] = _CONTENTADDRESSABLESTORAGE
+
+
+_CAPABILITIES = _descriptor.ServiceDescriptor(
+  name='Capabilities',
+  full_name='build.bazel.remote.execution.v2.Capabilities',
+  file=DESCRIPTOR,
+  index=3,
+  options=None,
+  serialized_start=8863,
+  serialized_end=9052,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='GetCapabilities',
+    full_name='build.bazel.remote.execution.v2.Capabilities.GetCapabilities',
+    index=0,
+    containing_service=None,
+    input_type=_GETCAPABILITIESREQUEST,
+    output_type=_SERVERCAPABILITIES,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002%\022#/v2/{instance_name=**}/capabilities')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_CAPABILITIES)
+
+DESCRIPTOR.services_by_name['Capabilities'] = _CAPABILITIES
+
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution_pb2_grpc.py b/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution_pb2_grpc.py
new file mode 100644
index 000000000..3769a680d
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/remote/execution/v2/remote_execution_pb2_grpc.py
@@ -0,0 +1,593 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.build.bazel.remote.execution.v2 import remote_execution_pb2 as build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2
+from buildstream._protos.google.longrunning import operations_pb2 as google_dot_longrunning_dot_operations__pb2
+
+
+class ExecutionStub(object):
+  """The Remote Execution API is used to execute an
+  [Action][build.bazel.remote.execution.v2.Action] on the remote
+  workers.
+
+  As with other services in the Remote Execution API, any call may return an
+  error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+  information about when the client should retry the request; clients SHOULD
+  respect the information provided.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.Execute = channel.unary_stream(
+        '/build.bazel.remote.execution.v2.Execution/Execute',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ExecuteRequest.SerializeToString,
+        response_deserializer=google_dot_longrunning_dot_operations__pb2.Operation.FromString,
+        )
+    self.WaitExecution = channel.unary_stream(
+        '/build.bazel.remote.execution.v2.Execution/WaitExecution',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.WaitExecutionRequest.SerializeToString,
+        response_deserializer=google_dot_longrunning_dot_operations__pb2.Operation.FromString,
+        )
+
+
+class ExecutionServicer(object):
+  """The Remote Execution API is used to execute an
+  [Action][build.bazel.remote.execution.v2.Action] on the remote
+  workers.
+
+  As with other services in the Remote Execution API, any call may return an
+  error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+  information about when the client should retry the request; clients SHOULD
+  respect the information provided.
+  """
+
+  def Execute(self, request, context):
+    """Execute an action remotely.
+
+    In order to execute an action, the client must first upload all of the
+    inputs, the
+    [Command][build.bazel.remote.execution.v2.Command] to run, and the
+    [Action][build.bazel.remote.execution.v2.Action] into the
+    [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage].
+    It then calls `Execute` with an `action_digest` referring to them. The
+    server will run the action and eventually return the result.
+
+    The input `Action`'s fields MUST meet the various canonicalization
+    requirements specified in the documentation for their types so that it has
+    the same digest as other logically equivalent `Action`s. The server MAY
+    enforce the requirements and return errors if a non-canonical input is
+    received. It MAY also proceed without verifying some or all of the
+    requirements, such as for performance reasons. If the server does not
+    verify the requirement, then it will treat the `Action` as distinct from
+    another logically equivalent action if they hash differently.
+
+    Returns a stream of
+    [google.longrunning.Operation][google.longrunning.Operation] messages
+    describing the resulting execution, with eventual `response`
+    [ExecuteResponse][build.bazel.remote.execution.v2.ExecuteResponse]. The
+    `metadata` on the operation is of type
+    [ExecuteOperationMetadata][build.bazel.remote.execution.v2.ExecuteOperationMetadata].
+
+    If the client remains connected after the first response is returned after
+    the server, then updates are streamed as if the client had called
+    [WaitExecution][build.bazel.remote.execution.v2.Execution.WaitExecution]
+    until the execution completes or the request reaches an error. The
+    operation can also be queried using [Operations
+    API][google.longrunning.Operations.GetOperation].
+
+    The server NEED NOT implement other methods or functionality of the
+    Operations API.
+
+    Errors discovered during creation of the `Operation` will be reported
+    as gRPC Status errors, while errors that occurred while running the
+    action will be reported in the `status` field of the `ExecuteResponse`. The
+    server MUST NOT set the `error` field of the `Operation` proto.
+    The possible errors include:
+    * `INVALID_ARGUMENT`: One or more arguments are invalid.
+    * `FAILED_PRECONDITION`: One or more errors occurred in setting up the
+    action requested, such as a missing input or command or no worker being
+    available. The client may be able to fix the errors and retry.
+    * `RESOURCE_EXHAUSTED`: There is insufficient quota of some resource to run
+    the action.
+    * `UNAVAILABLE`: Due to a transient condition, such as all workers being
+    occupied (and the server does not support a queue), the action could not
+    be started. The client should retry.
+    * `INTERNAL`: An internal error occurred in the execution engine or the
+    worker.
+    * `DEADLINE_EXCEEDED`: The execution timed out.
+
+    In the case of a missing input or command, the server SHOULD additionally
+    send a [PreconditionFailure][google.rpc.PreconditionFailure] error detail
+    where, for each requested blob not present in the CAS, there is a
+    `Violation` with a `type` of `MISSING` and a `subject` of
+    `"blobs/{hash}/{size}"` indicating the digest of the missing blob.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def WaitExecution(self, request, context):
+    """Wait for an execution operation to complete. When the client initially
+    makes the request, the server immediately responds with the current status
+    of the execution. The server will leave the request stream open until the
+    operation completes, and then respond with the completed operation. The
+    server MAY choose to stream additional updates as execution progresses,
+    such as to provide an update as to the state of the execution.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ExecutionServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'Execute': grpc.unary_stream_rpc_method_handler(
+          servicer.Execute,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ExecuteRequest.FromString,
+          response_serializer=google_dot_longrunning_dot_operations__pb2.Operation.SerializeToString,
+      ),
+      'WaitExecution': grpc.unary_stream_rpc_method_handler(
+          servicer.WaitExecution,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.WaitExecutionRequest.FromString,
+          response_serializer=google_dot_longrunning_dot_operations__pb2.Operation.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'build.bazel.remote.execution.v2.Execution', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
+
+
+class ActionCacheStub(object):
+  """The action cache API is used to query whether a given action has already been
+  performed and, if so, retrieve its result. Unlike the
+  [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage],
+  which addresses blobs by their own content, the action cache addresses the
+  [ActionResult][build.bazel.remote.execution.v2.ActionResult] by a
+  digest of the encoded [Action][build.bazel.remote.execution.v2.Action]
+  which produced them.
+
+  The lifetime of entries in the action cache is implementation-specific, but
+  the server SHOULD assume that more recently used entries are more likely to
+  be used again. Additionally, action cache implementations SHOULD ensure that
+  any blobs referenced in the
+  [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage]
+  are still valid when returning a result.
+
+  As with other services in the Remote Execution API, any call may return an
+  error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+  information about when the client should retry the request; clients SHOULD
+  respect the information provided.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.GetActionResult = channel.unary_unary(
+        '/build.bazel.remote.execution.v2.ActionCache/GetActionResult',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetActionResultRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ActionResult.FromString,
+        )
+    self.UpdateActionResult = channel.unary_unary(
+        '/build.bazel.remote.execution.v2.ActionCache/UpdateActionResult',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.UpdateActionResultRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ActionResult.FromString,
+        )
+
+
+class ActionCacheServicer(object):
+  """The action cache API is used to query whether a given action has already been
+  performed and, if so, retrieve its result. Unlike the
+  [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage],
+  which addresses blobs by their own content, the action cache addresses the
+  [ActionResult][build.bazel.remote.execution.v2.ActionResult] by a
+  digest of the encoded [Action][build.bazel.remote.execution.v2.Action]
+  which produced them.
+
+  The lifetime of entries in the action cache is implementation-specific, but
+  the server SHOULD assume that more recently used entries are more likely to
+  be used again. Additionally, action cache implementations SHOULD ensure that
+  any blobs referenced in the
+  [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage]
+  are still valid when returning a result.
+
+  As with other services in the Remote Execution API, any call may return an
+  error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+  information about when the client should retry the request; clients SHOULD
+  respect the information provided.
+  """
+
+  def GetActionResult(self, request, context):
+    """Retrieve a cached execution result.
+
+    Errors:
+    * `NOT_FOUND`: The requested `ActionResult` is not in the cache.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def UpdateActionResult(self, request, context):
+    """Upload a new execution result.
+
+    This method is intended for servers which implement the distributed cache
+    independently of the
+    [Execution][build.bazel.remote.execution.v2.Execution] API. As a
+    result, it is OPTIONAL for servers to implement.
+
+    In order to allow the server to perform access control based on the type of
+    action, and to assist with client debugging, the client MUST first upload
+    the [Action][build.bazel.remote.execution.v2.Execution] that produced the
+    result, along with its
+    [Command][build.bazel.remote.execution.v2.Command], into the
+    `ContentAddressableStorage`.
+
+    Errors:
+    * `NOT_IMPLEMENTED`: This method is not supported by the server.
+    * `RESOURCE_EXHAUSTED`: There is insufficient storage space to add the
+    entry to the cache.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ActionCacheServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'GetActionResult': grpc.unary_unary_rpc_method_handler(
+          servicer.GetActionResult,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetActionResultRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ActionResult.SerializeToString,
+      ),
+      'UpdateActionResult': grpc.unary_unary_rpc_method_handler(
+          servicer.UpdateActionResult,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.UpdateActionResultRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ActionResult.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'build.bazel.remote.execution.v2.ActionCache', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
+
+
+class ContentAddressableStorageStub(object):
+  """The CAS (content-addressable storage) is used to store the inputs to and
+  outputs from the execution service. Each piece of content is addressed by the
+  digest of its binary data.
+
+  Most of the binary data stored in the CAS is opaque to the execution engine,
+  and is only used as a communication medium. In order to build an
+  [Action][build.bazel.remote.execution.v2.Action],
+  however, the client will need to also upload the
+  [Command][build.bazel.remote.execution.v2.Command] and input root
+  [Directory][build.bazel.remote.execution.v2.Directory] for the Action.
+  The Command and Directory messages must be marshalled to wire format and then
+  uploaded under the hash as with any other piece of content. In practice, the
+  input root directory is likely to refer to other Directories in its
+  hierarchy, which must also each be uploaded on their own.
+
+  For small file uploads the client should group them together and call
+  [BatchUpdateBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchUpdateBlobs]
+  on chunks of no more than 10 MiB. For large uploads, the client must use the
+  [Write method][google.bytestream.ByteStream.Write] of the ByteStream API. The
+  `resource_name` is `{instance_name}/uploads/{uuid}/blobs/{hash}/{size}`,
+  where `instance_name` is as described in the next paragraph, `uuid` is a
+  version 4 UUID generated by the client, and `hash` and `size` are the
+  [Digest][build.bazel.remote.execution.v2.Digest] of the blob. The
+  `uuid` is used only to avoid collisions when multiple clients try to upload
+  the same file (or the same client tries to upload the file multiple times at
+  once on different threads), so the client MAY reuse the `uuid` for uploading
+  different blobs. The `resource_name` may optionally have a trailing filename
+  (or other metadata) for a client to use if it is storing URLs, as in
+  `{instance}/uploads/{uuid}/blobs/{hash}/{size}/foo/bar/baz.cc`. Anything
+  after the `size` is ignored.
+
+  A single server MAY support multiple instances of the execution system, each
+  with their own workers, storage, cache, etc. The exact relationship between
+  instances is up to the server. If the server does, then the `instance_name`
+  is an identifier, possibly containing multiple path segments, used to
+  distinguish between the various instances on the server, in a manner defined
+  by the server. For servers which do not support multiple instances, then the
+  `instance_name` is the empty path and the leading slash is omitted, so that
+  the `resource_name` becomes `uploads/{uuid}/blobs/{hash}/{size}`.
+
+  When attempting an upload, if another client has already completed the upload
+  (which may occur in the middle of a single upload if another client uploads
+  the same blob concurrently), the request will terminate immediately with
+  a response whose `committed_size` is the full size of the uploaded file
+  (regardless of how much data was transmitted by the client). If the client
+  completes the upload but the
+  [Digest][build.bazel.remote.execution.v2.Digest] does not match, an
+  `INVALID_ARGUMENT` error will be returned. In either case, the client should
+  not attempt to retry the upload.
+
+  For downloading blobs, the client must use the
+  [Read method][google.bytestream.ByteStream.Read] of the ByteStream API, with
+  a `resource_name` of `"{instance_name}/blobs/{hash}/{size}"`, where
+  `instance_name` is the instance name (see above), and `hash` and `size` are
+  the [Digest][build.bazel.remote.execution.v2.Digest] of the blob.
+
+  The lifetime of entries in the CAS is implementation specific, but it SHOULD
+  be long enough to allow for newly-added and recently looked-up entries to be
+  used in subsequent calls (e.g. to
+  [Execute][build.bazel.remote.execution.v2.Execution.Execute]).
+
+  As with other services in the Remote Execution API, any call may return an
+  error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+  information about when the client should retry the request; clients SHOULD
+  respect the information provided.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.FindMissingBlobs = channel.unary_unary(
+        '/build.bazel.remote.execution.v2.ContentAddressableStorage/FindMissingBlobs',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.FindMissingBlobsRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.FindMissingBlobsResponse.FromString,
+        )
+    self.BatchUpdateBlobs = channel.unary_unary(
+        '/build.bazel.remote.execution.v2.ContentAddressableStorage/BatchUpdateBlobs',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchUpdateBlobsRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchUpdateBlobsResponse.FromString,
+        )
+    self.BatchReadBlobs = channel.unary_unary(
+        '/build.bazel.remote.execution.v2.ContentAddressableStorage/BatchReadBlobs',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchReadBlobsRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchReadBlobsResponse.FromString,
+        )
+    self.GetTree = channel.unary_stream(
+        '/build.bazel.remote.execution.v2.ContentAddressableStorage/GetTree',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetTreeRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetTreeResponse.FromString,
+        )
+
+
+class ContentAddressableStorageServicer(object):
+  """The CAS (content-addressable storage) is used to store the inputs to and
+  outputs from the execution service. Each piece of content is addressed by the
+  digest of its binary data.
+
+  Most of the binary data stored in the CAS is opaque to the execution engine,
+  and is only used as a communication medium. In order to build an
+  [Action][build.bazel.remote.execution.v2.Action],
+  however, the client will need to also upload the
+  [Command][build.bazel.remote.execution.v2.Command] and input root
+  [Directory][build.bazel.remote.execution.v2.Directory] for the Action.
+  The Command and Directory messages must be marshalled to wire format and then
+  uploaded under the hash as with any other piece of content. In practice, the
+  input root directory is likely to refer to other Directories in its
+  hierarchy, which must also each be uploaded on their own.
+
+  For small file uploads the client should group them together and call
+  [BatchUpdateBlobs][build.bazel.remote.execution.v2.ContentAddressableStorage.BatchUpdateBlobs]
+  on chunks of no more than 10 MiB. For large uploads, the client must use the
+  [Write method][google.bytestream.ByteStream.Write] of the ByteStream API. The
+  `resource_name` is `{instance_name}/uploads/{uuid}/blobs/{hash}/{size}`,
+  where `instance_name` is as described in the next paragraph, `uuid` is a
+  version 4 UUID generated by the client, and `hash` and `size` are the
+  [Digest][build.bazel.remote.execution.v2.Digest] of the blob. The
+  `uuid` is used only to avoid collisions when multiple clients try to upload
+  the same file (or the same client tries to upload the file multiple times at
+  once on different threads), so the client MAY reuse the `uuid` for uploading
+  different blobs. The `resource_name` may optionally have a trailing filename
+  (or other metadata) for a client to use if it is storing URLs, as in
+  `{instance}/uploads/{uuid}/blobs/{hash}/{size}/foo/bar/baz.cc`. Anything
+  after the `size` is ignored.
+
+  A single server MAY support multiple instances of the execution system, each
+  with their own workers, storage, cache, etc. The exact relationship between
+  instances is up to the server. If the server does, then the `instance_name`
+  is an identifier, possibly containing multiple path segments, used to
+  distinguish between the various instances on the server, in a manner defined
+  by the server. For servers which do not support multiple instances, then the
+  `instance_name` is the empty path and the leading slash is omitted, so that
+  the `resource_name` becomes `uploads/{uuid}/blobs/{hash}/{size}`.
+
+  When attempting an upload, if another client has already completed the upload
+  (which may occur in the middle of a single upload if another client uploads
+  the same blob concurrently), the request will terminate immediately with
+  a response whose `committed_size` is the full size of the uploaded file
+  (regardless of how much data was transmitted by the client). If the client
+  completes the upload but the
+  [Digest][build.bazel.remote.execution.v2.Digest] does not match, an
+  `INVALID_ARGUMENT` error will be returned. In either case, the client should
+  not attempt to retry the upload.
+
+  For downloading blobs, the client must use the
+  [Read method][google.bytestream.ByteStream.Read] of the ByteStream API, with
+  a `resource_name` of `"{instance_name}/blobs/{hash}/{size}"`, where
+  `instance_name` is the instance name (see above), and `hash` and `size` are
+  the [Digest][build.bazel.remote.execution.v2.Digest] of the blob.
+
+  The lifetime of entries in the CAS is implementation specific, but it SHOULD
+  be long enough to allow for newly-added and recently looked-up entries to be
+  used in subsequent calls (e.g. to
+  [Execute][build.bazel.remote.execution.v2.Execution.Execute]).
+
+  As with other services in the Remote Execution API, any call may return an
+  error with a [RetryInfo][google.rpc.RetryInfo] error detail providing
+  information about when the client should retry the request; clients SHOULD
+  respect the information provided.
+  """
+
+  def FindMissingBlobs(self, request, context):
+    """Determine if blobs are present in the CAS.
+
+    Clients can use this API before uploading blobs to determine which ones are
+    already present in the CAS and do not need to be uploaded again.
+
+    There are no method-specific errors.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def BatchUpdateBlobs(self, request, context):
+    """Upload many blobs at once.
+
+    The server may enforce a limit of the combined total size of blobs
+    to be uploaded using this API. This limit may be obtained using the
+    [Capabilities][build.bazel.remote.execution.v2.Capabilities] API.
+    Requests exceeding the limit should either be split into smaller
+    chunks or uploaded using the
+    [ByteStream API][google.bytestream.ByteStream], as appropriate.
+
+    This request is equivalent to calling a Bytestream `Write` request
+    on each individual blob, in parallel. The requests may succeed or fail
+    independently.
+
+    Errors:
+    * `INVALID_ARGUMENT`: The client attempted to upload more than the
+    server supported limit.
+
+    Individual requests may return the following errors, additionally:
+    * `RESOURCE_EXHAUSTED`: There is insufficient disk quota to store the blob.
+    * `INVALID_ARGUMENT`: The
+    [Digest][build.bazel.remote.execution.v2.Digest] does not match the
+    provided data.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def BatchReadBlobs(self, request, context):
+    """Download many blobs at once.
+
+    The server may enforce a limit of the combined total size of blobs
+    to be downloaded using this API. This limit may be obtained using the
+    [Capabilities][build.bazel.remote.execution.v2.Capabilities] API.
+    Requests exceeding the limit should either be split into smaller
+    chunks or downloaded using the
+    [ByteStream API][google.bytestream.ByteStream], as appropriate.
+
+    This request is equivalent to calling a Bytestream `Read` request
+    on each individual blob, in parallel. The requests may succeed or fail
+    independently.
+
+    Errors:
+    * `INVALID_ARGUMENT`: The client attempted to read more than the
+    server supported limit.
+
+    Every error on individual read will be returned in the corresponding digest
+    status.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def GetTree(self, request, context):
+    """Fetch the entire directory tree rooted at a node.
+
+    This request must be targeted at a
+    [Directory][build.bazel.remote.execution.v2.Directory] stored in the
+    [ContentAddressableStorage][build.bazel.remote.execution.v2.ContentAddressableStorage]
+    (CAS). The server will enumerate the `Directory` tree recursively and
+    return every node descended from the root.
+
+    The GetTreeRequest.page_token parameter can be used to skip ahead in
+    the stream (e.g. when retrying a partially completed and aborted request),
+    by setting it to a value taken from GetTreeResponse.next_page_token of the
+    last successfully processed GetTreeResponse).
+
+    The exact traversal order is unspecified and, unless retrieving subsequent
+    pages from an earlier request, is not guaranteed to be stable across
+    multiple invocations of `GetTree`.
+
+    If part of the tree is missing from the CAS, the server will return the
+    portion present and omit the rest.
+
+    * `NOT_FOUND`: The requested tree root is not present in the CAS.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ContentAddressableStorageServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'FindMissingBlobs': grpc.unary_unary_rpc_method_handler(
+          servicer.FindMissingBlobs,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.FindMissingBlobsRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.FindMissingBlobsResponse.SerializeToString,
+      ),
+      'BatchUpdateBlobs': grpc.unary_unary_rpc_method_handler(
+          servicer.BatchUpdateBlobs,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchUpdateBlobsRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchUpdateBlobsResponse.SerializeToString,
+      ),
+      'BatchReadBlobs': grpc.unary_unary_rpc_method_handler(
+          servicer.BatchReadBlobs,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchReadBlobsRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.BatchReadBlobsResponse.SerializeToString,
+      ),
+      'GetTree': grpc.unary_stream_rpc_method_handler(
+          servicer.GetTree,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetTreeRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetTreeResponse.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'build.bazel.remote.execution.v2.ContentAddressableStorage', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
+
+
+class CapabilitiesStub(object):
+  """The Capabilities service may be used by remote execution clients to query
+  various server properties, in order to self-configure or return meaningful
+  error messages.
+
+  The query may include a particular `instance_name`, in which case the values
+  returned will pertain to that instance.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.GetCapabilities = channel.unary_unary(
+        '/build.bazel.remote.execution.v2.Capabilities/GetCapabilities',
+        request_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetCapabilitiesRequest.SerializeToString,
+        response_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ServerCapabilities.FromString,
+        )
+
+
+class CapabilitiesServicer(object):
+  """The Capabilities service may be used by remote execution clients to query
+  various server properties, in order to self-configure or return meaningful
+  error messages.
+
+  The query may include a particular `instance_name`, in which case the values
+  returned will pertain to that instance.
+  """
+
+  def GetCapabilities(self, request, context):
+    """GetCapabilities returns the server capabilities configuration.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_CapabilitiesServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'GetCapabilities': grpc.unary_unary_rpc_method_handler(
+          servicer.GetCapabilities,
+          request_deserializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.GetCapabilitiesRequest.FromString,
+          response_serializer=build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.ServerCapabilities.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'build.bazel.remote.execution.v2.Capabilities', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/src/buildstream/_protos/build/bazel/semver/__init__.py b/src/buildstream/_protos/build/bazel/semver/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/semver/__init__.py
diff --git a/src/buildstream/_protos/build/bazel/semver/semver.proto b/src/buildstream/_protos/build/bazel/semver/semver.proto
new file mode 100644
index 000000000..2caf76bcc
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/semver/semver.proto
@@ -0,0 +1,24 @@
+// Copyright 2018 The Bazel Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package build.bazel.semver;
+
+message SemVer {
+  int32 major = 1;
+  int32 minor = 2;
+  int32 patch = 3;
+  string prerelease = 4;
+}
diff --git a/src/buildstream/_protos/build/bazel/semver/semver_pb2.py b/src/buildstream/_protos/build/bazel/semver/semver_pb2.py
new file mode 100644
index 000000000..a36cf722a
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/semver/semver_pb2.py
@@ -0,0 +1,90 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: build/bazel/semver/semver.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='build/bazel/semver/semver.proto',
+  package='build.bazel.semver',
+  syntax='proto3',
+  serialized_pb=_b('\n\x1f\x62uild/bazel/semver/semver.proto\x12\x12\x62uild.bazel.semver\"I\n\x06SemVer\x12\r\n\x05major\x18\x01 \x01(\x05\x12\r\n\x05minor\x18\x02 \x01(\x05\x12\r\n\x05patch\x18\x03 \x01(\x05\x12\x12\n\nprerelease\x18\x04 \x01(\tb\x06proto3')
+)
+
+
+
+
+_SEMVER = _descriptor.Descriptor(
+  name='SemVer',
+  full_name='build.bazel.semver.SemVer',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='major', full_name='build.bazel.semver.SemVer.major', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='minor', full_name='build.bazel.semver.SemVer.minor', index=1,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='patch', full_name='build.bazel.semver.SemVer.patch', index=2,
+      number=3, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='prerelease', full_name='build.bazel.semver.SemVer.prerelease', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=55,
+  serialized_end=128,
+)
+
+DESCRIPTOR.message_types_by_name['SemVer'] = _SEMVER
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+SemVer = _reflection.GeneratedProtocolMessageType('SemVer', (_message.Message,), dict(
+  DESCRIPTOR = _SEMVER,
+  __module__ = 'build.bazel.semver.semver_pb2'
+  # @@protoc_insertion_point(class_scope:build.bazel.semver.SemVer)
+  ))
+_sym_db.RegisterMessage(SemVer)
+
+
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/build/bazel/semver/semver_pb2_grpc.py b/src/buildstream/_protos/build/bazel/semver/semver_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/src/buildstream/_protos/build/bazel/semver/semver_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
diff --git a/src/buildstream/_protos/buildstream/__init__.py b/src/buildstream/_protos/buildstream/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/__init__.py
diff --git a/src/buildstream/_protos/buildstream/v2/__init__.py b/src/buildstream/_protos/buildstream/v2/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/__init__.py
diff --git a/src/buildstream/_protos/buildstream/v2/artifact.proto b/src/buildstream/_protos/buildstream/v2/artifact.proto
new file mode 100644
index 000000000..56ddbca6b
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/artifact.proto
@@ -0,0 +1,88 @@
+// Copyright 2019 Bloomberg Finance LP
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Authors
+//      Raoul Hidalgo Charman <raoul.hidalgo.charman@gmail.com>
+
+syntax = "proto3";
+
+package buildstream.v2;
+
+import "build/bazel/remote/execution/v2/remote_execution.proto";
+import "google/api/annotations.proto";
+
+service ArtifactService {
+  // Retrieves an Artifact message
+  //
+  // Errors:
+  // * `NOT_FOUND`: Artifact not found on server
+  rpc GetArtifact(GetArtifactRequest) returns (Artifact) {}
+
+  // Sets an Artifact message
+  //
+  // Errors:
+  // * `FAILED_PRECONDITION`: Files specified in upload aren't present in CAS
+  rpc UpdateArtifact(UpdateArtifactRequest) returns (Artifact) {}
+}
+
+message Artifact {
+  // This version number must always be present and can be used to
+  // further indicate presence or absence of parts of the proto at a
+  // later date.  It only needs incrementing if a change to what is
+  // *mandatory* changes.
+  int32 version = 1;
+  // Core metadata
+  bool build_success = 2;
+  string build_error = 3;  // optional
+  string build_error_details = 4;
+  string strong_key = 5;
+  string weak_key = 6;
+  bool was_workspaced = 7;
+  // digest of a Directory
+  build.bazel.remote.execution.v2.Digest files = 8;
+
+  // Information about the build dependencies
+  message Dependency {
+    string element_name = 1;
+    string cache_key = 2;
+    bool was_workspaced = 3;
+  };
+  repeated Dependency build_deps = 9;
+
+  // The public data is a yaml file which is stored into the CAS
+  // Digest is of a directory
+  build.bazel.remote.execution.v2.Digest public_data = 10;
+
+  // The logs are stored in the CAS
+  message LogFile {
+    string name = 1;
+    // digest of a file
+    build.bazel.remote.execution.v2.Digest digest = 2;
+  };
+  repeated LogFile logs = 11;  // Zero or more log files here
+
+  // digest of a directory
+  build.bazel.remote.execution.v2.Digest buildtree = 12;  // optional
+}
+
+message GetArtifactRequest {
+  string instance_name = 1;
+  string cache_key = 2;
+}
+
+message UpdateArtifactRequest {
+  string instance_name = 1;
+  string cache_key = 2;
+  Artifact artifact = 3;
+}
diff --git a/src/buildstream/_protos/buildstream/v2/artifact_pb2.py b/src/buildstream/_protos/buildstream/v2/artifact_pb2.py
new file mode 100644
index 000000000..c56d1ae8a
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/artifact_pb2.py
@@ -0,0 +1,387 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: buildstream/v2/artifact.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.build.bazel.remote.execution.v2 import remote_execution_pb2 as build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='buildstream/v2/artifact.proto',
+  package='buildstream.v2',
+  syntax='proto3',
+  serialized_options=None,
+  serialized_pb=_b('\n\x1d\x62uildstream/v2/artifact.proto\x12\x0e\x62uildstream.v2\x1a\x36\x62uild/bazel/remote/execution/v2/remote_execution.proto\x1a\x1cgoogle/api/annotations.proto\"\xde\x04\n\x08\x41rtifact\x12\x0f\n\x07version\x18\x01 \x01(\x05\x12\x15\n\rbuild_success\x18\x02 \x01(\x08\x12\x13\n\x0b\x62uild_error\x18\x03 \x01(\t\x12\x1b\n\x13\x62uild_error_details\x18\x04 \x01(\t\x12\x12\n\nstrong_key\x18\x05 \x01(\t\x12\x10\n\x08weak_key\x18\x06 \x01(\t\x12\x16\n\x0ewas_workspaced\x18\x07 \x01(\x08\x12\x36\n\x05\x66iles\x18\x08 \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\x12\x37\n\nbuild_deps\x18\t \x03(\x0b\x32#.buildstream.v2.Artifact.Dependency\x12<\n\x0bpublic_data\x18\n \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\x12.\n\x04logs\x18\x0b \x03(\x0b\x32 .buildstream.v2.Artifact.LogFile\x12:\n\tbuildtree\x18\x0c \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\x1aM\n\nDependency\x12\x14\n\x0c\x65lement_name\x18\x01 \x01(\t\x12\x11\n\tcache_key\x18\x02 \x01(\t\x12\x16\n\x0ewas_workspaced\x18\x03 \x01(\x08\x1aP\n\x07LogFile\x12\x0c\n\x04name\x18\x01 \x01(\t\x12\x37\n\x06\x64igest\x18\x02 \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\">\n\x12GetArtifactRequest\x12\x15\n\rinstance_name\x18\x01 \x01(\t\x12\x11\n\tcache_key\x18\x02 \x01(\t\"m\n\x15UpdateArtifactRequest\x12\x15\n\rinstance_name\x18\x01 \x01(\t\x12\x11\n\tcache_key\x18\x02 \x01(\t\x12*\n\x08\x61rtifact\x18\x03 \x01(\x0b\x32\x18.buildstream.v2.Artifact2\xb5\x01\n\x0f\x41rtifactService\x12M\n\x0bGetArtifact\x12\".buildstream.v2.GetArtifactRequest\x1a\x18.buildstream.v2.Artifact\"\x00\x12S\n\x0eUpdateArtifact\x12%.buildstream.v2.UpdateArtifactRequest\x1a\x18.buildstream.v2.Artifact\"\x00\x62\x06proto3')
+  ,
+  dependencies=[build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.DESCRIPTOR,google_dot_api_dot_annotations__pb2.DESCRIPTOR,])
+
+
+
+
+_ARTIFACT_DEPENDENCY = _descriptor.Descriptor(
+  name='Dependency',
+  full_name='buildstream.v2.Artifact.Dependency',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='element_name', full_name='buildstream.v2.Artifact.Dependency.element_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='cache_key', full_name='buildstream.v2.Artifact.Dependency.cache_key', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='was_workspaced', full_name='buildstream.v2.Artifact.Dependency.was_workspaced', index=2,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=583,
+  serialized_end=660,
+)
+
+_ARTIFACT_LOGFILE = _descriptor.Descriptor(
+  name='LogFile',
+  full_name='buildstream.v2.Artifact.LogFile',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='buildstream.v2.Artifact.LogFile.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='buildstream.v2.Artifact.LogFile.digest', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=662,
+  serialized_end=742,
+)
+
+_ARTIFACT = _descriptor.Descriptor(
+  name='Artifact',
+  full_name='buildstream.v2.Artifact',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='version', full_name='buildstream.v2.Artifact.version', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='build_success', full_name='buildstream.v2.Artifact.build_success', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='build_error', full_name='buildstream.v2.Artifact.build_error', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='build_error_details', full_name='buildstream.v2.Artifact.build_error_details', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='strong_key', full_name='buildstream.v2.Artifact.strong_key', index=4,
+      number=5, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='weak_key', full_name='buildstream.v2.Artifact.weak_key', index=5,
+      number=6, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='was_workspaced', full_name='buildstream.v2.Artifact.was_workspaced', index=6,
+      number=7, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='files', full_name='buildstream.v2.Artifact.files', index=7,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='build_deps', full_name='buildstream.v2.Artifact.build_deps', index=8,
+      number=9, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='public_data', full_name='buildstream.v2.Artifact.public_data', index=9,
+      number=10, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='logs', full_name='buildstream.v2.Artifact.logs', index=10,
+      number=11, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='buildtree', full_name='buildstream.v2.Artifact.buildtree', index=11,
+      number=12, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[_ARTIFACT_DEPENDENCY, _ARTIFACT_LOGFILE, ],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=136,
+  serialized_end=742,
+)
+
+
+_GETARTIFACTREQUEST = _descriptor.Descriptor(
+  name='GetArtifactRequest',
+  full_name='buildstream.v2.GetArtifactRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='buildstream.v2.GetArtifactRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='cache_key', full_name='buildstream.v2.GetArtifactRequest.cache_key', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=744,
+  serialized_end=806,
+)
+
+
+_UPDATEARTIFACTREQUEST = _descriptor.Descriptor(
+  name='UpdateArtifactRequest',
+  full_name='buildstream.v2.UpdateArtifactRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='buildstream.v2.UpdateArtifactRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='cache_key', full_name='buildstream.v2.UpdateArtifactRequest.cache_key', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='artifact', full_name='buildstream.v2.UpdateArtifactRequest.artifact', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=808,
+  serialized_end=917,
+)
+
+_ARTIFACT_DEPENDENCY.containing_type = _ARTIFACT
+_ARTIFACT_LOGFILE.fields_by_name['digest'].message_type = build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2._DIGEST
+_ARTIFACT_LOGFILE.containing_type = _ARTIFACT
+_ARTIFACT.fields_by_name['files'].message_type = build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2._DIGEST
+_ARTIFACT.fields_by_name['build_deps'].message_type = _ARTIFACT_DEPENDENCY
+_ARTIFACT.fields_by_name['public_data'].message_type = build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2._DIGEST
+_ARTIFACT.fields_by_name['logs'].message_type = _ARTIFACT_LOGFILE
+_ARTIFACT.fields_by_name['buildtree'].message_type = build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2._DIGEST
+_UPDATEARTIFACTREQUEST.fields_by_name['artifact'].message_type = _ARTIFACT
+DESCRIPTOR.message_types_by_name['Artifact'] = _ARTIFACT
+DESCRIPTOR.message_types_by_name['GetArtifactRequest'] = _GETARTIFACTREQUEST
+DESCRIPTOR.message_types_by_name['UpdateArtifactRequest'] = _UPDATEARTIFACTREQUEST
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Artifact = _reflection.GeneratedProtocolMessageType('Artifact', (_message.Message,), dict(
+
+  Dependency = _reflection.GeneratedProtocolMessageType('Dependency', (_message.Message,), dict(
+    DESCRIPTOR = _ARTIFACT_DEPENDENCY,
+    __module__ = 'buildstream.v2.artifact_pb2'
+    # @@protoc_insertion_point(class_scope:buildstream.v2.Artifact.Dependency)
+    ))
+  ,
+
+  LogFile = _reflection.GeneratedProtocolMessageType('LogFile', (_message.Message,), dict(
+    DESCRIPTOR = _ARTIFACT_LOGFILE,
+    __module__ = 'buildstream.v2.artifact_pb2'
+    # @@protoc_insertion_point(class_scope:buildstream.v2.Artifact.LogFile)
+    ))
+  ,
+  DESCRIPTOR = _ARTIFACT,
+  __module__ = 'buildstream.v2.artifact_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.Artifact)
+  ))
+_sym_db.RegisterMessage(Artifact)
+_sym_db.RegisterMessage(Artifact.Dependency)
+_sym_db.RegisterMessage(Artifact.LogFile)
+
+GetArtifactRequest = _reflection.GeneratedProtocolMessageType('GetArtifactRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETARTIFACTREQUEST,
+  __module__ = 'buildstream.v2.artifact_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.GetArtifactRequest)
+  ))
+_sym_db.RegisterMessage(GetArtifactRequest)
+
+UpdateArtifactRequest = _reflection.GeneratedProtocolMessageType('UpdateArtifactRequest', (_message.Message,), dict(
+  DESCRIPTOR = _UPDATEARTIFACTREQUEST,
+  __module__ = 'buildstream.v2.artifact_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.UpdateArtifactRequest)
+  ))
+_sym_db.RegisterMessage(UpdateArtifactRequest)
+
+
+
+_ARTIFACTSERVICE = _descriptor.ServiceDescriptor(
+  name='ArtifactService',
+  full_name='buildstream.v2.ArtifactService',
+  file=DESCRIPTOR,
+  index=0,
+  serialized_options=None,
+  serialized_start=920,
+  serialized_end=1101,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='GetArtifact',
+    full_name='buildstream.v2.ArtifactService.GetArtifact',
+    index=0,
+    containing_service=None,
+    input_type=_GETARTIFACTREQUEST,
+    output_type=_ARTIFACT,
+    serialized_options=None,
+  ),
+  _descriptor.MethodDescriptor(
+    name='UpdateArtifact',
+    full_name='buildstream.v2.ArtifactService.UpdateArtifact',
+    index=1,
+    containing_service=None,
+    input_type=_UPDATEARTIFACTREQUEST,
+    output_type=_ARTIFACT,
+    serialized_options=None,
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_ARTIFACTSERVICE)
+
+DESCRIPTOR.services_by_name['ArtifactService'] = _ARTIFACTSERVICE
+
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/buildstream/v2/artifact_pb2_grpc.py b/src/buildstream/_protos/buildstream/v2/artifact_pb2_grpc.py
new file mode 100644
index 000000000..d355146af
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/artifact_pb2_grpc.py
@@ -0,0 +1,68 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.buildstream.v2 import artifact_pb2 as buildstream_dot_v2_dot_artifact__pb2
+
+
+class ArtifactServiceStub(object):
+  # missing associated documentation comment in .proto file
+  pass
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.GetArtifact = channel.unary_unary(
+        '/buildstream.v2.ArtifactService/GetArtifact',
+        request_serializer=buildstream_dot_v2_dot_artifact__pb2.GetArtifactRequest.SerializeToString,
+        response_deserializer=buildstream_dot_v2_dot_artifact__pb2.Artifact.FromString,
+        )
+    self.UpdateArtifact = channel.unary_unary(
+        '/buildstream.v2.ArtifactService/UpdateArtifact',
+        request_serializer=buildstream_dot_v2_dot_artifact__pb2.UpdateArtifactRequest.SerializeToString,
+        response_deserializer=buildstream_dot_v2_dot_artifact__pb2.Artifact.FromString,
+        )
+
+
+class ArtifactServiceServicer(object):
+  # missing associated documentation comment in .proto file
+  pass
+
+  def GetArtifact(self, request, context):
+    """Retrieves an Artifact message
+
+    Errors:
+    * `NOT_FOUND`: Artifact not found on server
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def UpdateArtifact(self, request, context):
+    """Sets an Artifact message
+
+    Errors:
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ArtifactServiceServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'GetArtifact': grpc.unary_unary_rpc_method_handler(
+          servicer.GetArtifact,
+          request_deserializer=buildstream_dot_v2_dot_artifact__pb2.GetArtifactRequest.FromString,
+          response_serializer=buildstream_dot_v2_dot_artifact__pb2.Artifact.SerializeToString,
+      ),
+      'UpdateArtifact': grpc.unary_unary_rpc_method_handler(
+          servicer.UpdateArtifact,
+          request_deserializer=buildstream_dot_v2_dot_artifact__pb2.UpdateArtifactRequest.FromString,
+          response_serializer=buildstream_dot_v2_dot_artifact__pb2.Artifact.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'buildstream.v2.ArtifactService', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/src/buildstream/_protos/buildstream/v2/buildstream.proto b/src/buildstream/_protos/buildstream/v2/buildstream.proto
new file mode 100644
index 000000000..f283d6f3f
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/buildstream.proto
@@ -0,0 +1,95 @@
+// Copyright 2018 Codethink Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package buildstream.v2;
+
+import "build/bazel/remote/execution/v2/remote_execution.proto";
+import "google/api/annotations.proto";
+
+service ReferenceStorage {
+  // Retrieve a CAS [Directory][build.bazel.remote.execution.v2.Directory]
+  // digest by name.
+  //
+  // Errors:
+  // * `NOT_FOUND`: The requested reference is not in the cache.
+  rpc GetReference(GetReferenceRequest) returns (GetReferenceResponse) {
+    option (google.api.http) = { get: "/v2/{instance_name=**}/buildstream/refs/{key}" };
+  }
+
+  // Associate a name with a CAS [Directory][build.bazel.remote.execution.v2.Directory]
+  // digest.
+  //
+  // Errors:
+  // * `RESOURCE_EXHAUSTED`: There is insufficient storage space to add the
+  //   entry to the cache.
+  rpc UpdateReference(UpdateReferenceRequest) returns (UpdateReferenceResponse) {
+    option (google.api.http) = { put: "/v2/{instance_name=**}/buildstream/refs/{key}" body: "digest" };
+  }
+
+  rpc Status(StatusRequest) returns (StatusResponse) {
+    option (google.api.http) = { put: "/v2/{instance_name=**}/buildstream/refs:status" };
+  }
+}
+
+message GetReferenceRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The name of the reference.
+  string key = 2;
+}
+
+message GetReferenceResponse {
+  // The digest of the CAS [Directory][build.bazel.remote.execution.v2.Directory].
+  build.bazel.remote.execution.v2.Digest digest = 1;
+}
+
+message UpdateReferenceRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The name of the reference.
+  repeated string keys = 2;
+
+  // The digest of the CAS [Directory][build.bazel.remote.execution.v2.Directory]
+  // to store in the cache.
+  build.bazel.remote.execution.v2.Digest digest = 3;
+}
+
+message UpdateReferenceResponse {
+}
+
+message StatusRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+}
+
+message StatusResponse {
+  // Whether reference updates are allowed for the connected client.
+  bool allow_updates = 1;
+}
diff --git a/src/buildstream/_protos/buildstream/v2/buildstream_pb2.py b/src/buildstream/_protos/buildstream/v2/buildstream_pb2.py
new file mode 100644
index 000000000..57fdae49d
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/buildstream_pb2.py
@@ -0,0 +1,325 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: buildstream/v2/buildstream.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.build.bazel.remote.execution.v2 import remote_execution_pb2 as build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='buildstream/v2/buildstream.proto',
+  package='buildstream.v2',
+  syntax='proto3',
+  serialized_pb=_b('\n buildstream/v2/buildstream.proto\x12\x0e\x62uildstream.v2\x1a\x36\x62uild/bazel/remote/execution/v2/remote_execution.proto\x1a\x1cgoogle/api/annotations.proto\"9\n\x13GetReferenceRequest\x12\x15\n\rinstance_name\x18\x01 \x01(\t\x12\x0b\n\x03key\x18\x02 \x01(\t\"O\n\x14GetReferenceResponse\x12\x37\n\x06\x64igest\x18\x01 \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\"v\n\x16UpdateReferenceRequest\x12\x15\n\rinstance_name\x18\x01 \x01(\t\x12\x0c\n\x04keys\x18\x02 \x03(\t\x12\x37\n\x06\x64igest\x18\x03 \x01(\x0b\x32\'.build.bazel.remote.execution.v2.Digest\"\x19\n\x17UpdateReferenceResponse\"&\n\rStatusRequest\x12\x15\n\rinstance_name\x18\x01 \x01(\t\"\'\n\x0eStatusResponse\x12\x15\n\rallow_updates\x18\x01 \x01(\x08\x32\xca\x03\n\x10ReferenceStorage\x12\x90\x01\n\x0cGetReference\x12#.buildstream.v2.GetReferenceRequest\x1a$.buildstream.v2.GetReferenceResponse\"5\x82\xd3\xe4\x93\x02/\x12-/v2/{instance_name=**}/buildstream/refs/{key}\x12\xa1\x01\n\x0fUpdateReference\x12&.buildstream.v2.UpdateReferenceRequest\x1a\'.buildstream.v2.UpdateReferenceResponse\"=\x82\xd3\xe4\x93\x02\x37\x1a-/v2/{instance_name=**}/buildstream/refs/{key}:\x06\x64igest\x12\x7f\n\x06Status\x12\x1d.buildstream.v2.StatusRequest\x1a\x1e.buildstream.v2.StatusResponse\"6\x82\xd3\xe4\x93\x02\x30\x1a./v2/{instance_name=**}/buildstream/refs:statusb\x06proto3')
+  ,
+  dependencies=[build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2.DESCRIPTOR,google_dot_api_dot_annotations__pb2.DESCRIPTOR,])
+
+
+
+
+_GETREFERENCEREQUEST = _descriptor.Descriptor(
+  name='GetReferenceRequest',
+  full_name='buildstream.v2.GetReferenceRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='buildstream.v2.GetReferenceRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='key', full_name='buildstream.v2.GetReferenceRequest.key', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=138,
+  serialized_end=195,
+)
+
+
+_GETREFERENCERESPONSE = _descriptor.Descriptor(
+  name='GetReferenceResponse',
+  full_name='buildstream.v2.GetReferenceResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='buildstream.v2.GetReferenceResponse.digest', index=0,
+      number=1, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=197,
+  serialized_end=276,
+)
+
+
+_UPDATEREFERENCEREQUEST = _descriptor.Descriptor(
+  name='UpdateReferenceRequest',
+  full_name='buildstream.v2.UpdateReferenceRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='buildstream.v2.UpdateReferenceRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='keys', full_name='buildstream.v2.UpdateReferenceRequest.keys', index=1,
+      number=2, type=9, cpp_type=9, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='digest', full_name='buildstream.v2.UpdateReferenceRequest.digest', index=2,
+      number=3, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=278,
+  serialized_end=396,
+)
+
+
+_UPDATEREFERENCERESPONSE = _descriptor.Descriptor(
+  name='UpdateReferenceResponse',
+  full_name='buildstream.v2.UpdateReferenceResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=398,
+  serialized_end=423,
+)
+
+
+_STATUSREQUEST = _descriptor.Descriptor(
+  name='StatusRequest',
+  full_name='buildstream.v2.StatusRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='instance_name', full_name='buildstream.v2.StatusRequest.instance_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=425,
+  serialized_end=463,
+)
+
+
+_STATUSRESPONSE = _descriptor.Descriptor(
+  name='StatusResponse',
+  full_name='buildstream.v2.StatusResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='allow_updates', full_name='buildstream.v2.StatusResponse.allow_updates', index=0,
+      number=1, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=465,
+  serialized_end=504,
+)
+
+_GETREFERENCERESPONSE.fields_by_name['digest'].message_type = build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2._DIGEST
+_UPDATEREFERENCEREQUEST.fields_by_name['digest'].message_type = build_dot_bazel_dot_remote_dot_execution_dot_v2_dot_remote__execution__pb2._DIGEST
+DESCRIPTOR.message_types_by_name['GetReferenceRequest'] = _GETREFERENCEREQUEST
+DESCRIPTOR.message_types_by_name['GetReferenceResponse'] = _GETREFERENCERESPONSE
+DESCRIPTOR.message_types_by_name['UpdateReferenceRequest'] = _UPDATEREFERENCEREQUEST
+DESCRIPTOR.message_types_by_name['UpdateReferenceResponse'] = _UPDATEREFERENCERESPONSE
+DESCRIPTOR.message_types_by_name['StatusRequest'] = _STATUSREQUEST
+DESCRIPTOR.message_types_by_name['StatusResponse'] = _STATUSRESPONSE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+GetReferenceRequest = _reflection.GeneratedProtocolMessageType('GetReferenceRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETREFERENCEREQUEST,
+  __module__ = 'buildstream.v2.buildstream_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.GetReferenceRequest)
+  ))
+_sym_db.RegisterMessage(GetReferenceRequest)
+
+GetReferenceResponse = _reflection.GeneratedProtocolMessageType('GetReferenceResponse', (_message.Message,), dict(
+  DESCRIPTOR = _GETREFERENCERESPONSE,
+  __module__ = 'buildstream.v2.buildstream_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.GetReferenceResponse)
+  ))
+_sym_db.RegisterMessage(GetReferenceResponse)
+
+UpdateReferenceRequest = _reflection.GeneratedProtocolMessageType('UpdateReferenceRequest', (_message.Message,), dict(
+  DESCRIPTOR = _UPDATEREFERENCEREQUEST,
+  __module__ = 'buildstream.v2.buildstream_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.UpdateReferenceRequest)
+  ))
+_sym_db.RegisterMessage(UpdateReferenceRequest)
+
+UpdateReferenceResponse = _reflection.GeneratedProtocolMessageType('UpdateReferenceResponse', (_message.Message,), dict(
+  DESCRIPTOR = _UPDATEREFERENCERESPONSE,
+  __module__ = 'buildstream.v2.buildstream_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.UpdateReferenceResponse)
+  ))
+_sym_db.RegisterMessage(UpdateReferenceResponse)
+
+StatusRequest = _reflection.GeneratedProtocolMessageType('StatusRequest', (_message.Message,), dict(
+  DESCRIPTOR = _STATUSREQUEST,
+  __module__ = 'buildstream.v2.buildstream_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.StatusRequest)
+  ))
+_sym_db.RegisterMessage(StatusRequest)
+
+StatusResponse = _reflection.GeneratedProtocolMessageType('StatusResponse', (_message.Message,), dict(
+  DESCRIPTOR = _STATUSRESPONSE,
+  __module__ = 'buildstream.v2.buildstream_pb2'
+  # @@protoc_insertion_point(class_scope:buildstream.v2.StatusResponse)
+  ))
+_sym_db.RegisterMessage(StatusResponse)
+
+
+
+_REFERENCESTORAGE = _descriptor.ServiceDescriptor(
+  name='ReferenceStorage',
+  full_name='buildstream.v2.ReferenceStorage',
+  file=DESCRIPTOR,
+  index=0,
+  options=None,
+  serialized_start=507,
+  serialized_end=965,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='GetReference',
+    full_name='buildstream.v2.ReferenceStorage.GetReference',
+    index=0,
+    containing_service=None,
+    input_type=_GETREFERENCEREQUEST,
+    output_type=_GETREFERENCERESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002/\022-/v2/{instance_name=**}/buildstream/refs/{key}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='UpdateReference',
+    full_name='buildstream.v2.ReferenceStorage.UpdateReference',
+    index=1,
+    containing_service=None,
+    input_type=_UPDATEREFERENCEREQUEST,
+    output_type=_UPDATEREFERENCERESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\0027\032-/v2/{instance_name=**}/buildstream/refs/{key}:\006digest')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='Status',
+    full_name='buildstream.v2.ReferenceStorage.Status',
+    index=2,
+    containing_service=None,
+    input_type=_STATUSREQUEST,
+    output_type=_STATUSRESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\0020\032./v2/{instance_name=**}/buildstream/refs:status')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_REFERENCESTORAGE)
+
+DESCRIPTOR.services_by_name['ReferenceStorage'] = _REFERENCESTORAGE
+
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/buildstream/v2/buildstream_pb2_grpc.py b/src/buildstream/_protos/buildstream/v2/buildstream_pb2_grpc.py
new file mode 100644
index 000000000..b3e653493
--- /dev/null
+++ b/src/buildstream/_protos/buildstream/v2/buildstream_pb2_grpc.py
@@ -0,0 +1,89 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.buildstream.v2 import buildstream_pb2 as buildstream_dot_v2_dot_buildstream__pb2
+
+
+class ReferenceStorageStub(object):
+  # missing associated documentation comment in .proto file
+  pass
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.GetReference = channel.unary_unary(
+        '/buildstream.v2.ReferenceStorage/GetReference',
+        request_serializer=buildstream_dot_v2_dot_buildstream__pb2.GetReferenceRequest.SerializeToString,
+        response_deserializer=buildstream_dot_v2_dot_buildstream__pb2.GetReferenceResponse.FromString,
+        )
+    self.UpdateReference = channel.unary_unary(
+        '/buildstream.v2.ReferenceStorage/UpdateReference',
+        request_serializer=buildstream_dot_v2_dot_buildstream__pb2.UpdateReferenceRequest.SerializeToString,
+        response_deserializer=buildstream_dot_v2_dot_buildstream__pb2.UpdateReferenceResponse.FromString,
+        )
+    self.Status = channel.unary_unary(
+        '/buildstream.v2.ReferenceStorage/Status',
+        request_serializer=buildstream_dot_v2_dot_buildstream__pb2.StatusRequest.SerializeToString,
+        response_deserializer=buildstream_dot_v2_dot_buildstream__pb2.StatusResponse.FromString,
+        )
+
+
+class ReferenceStorageServicer(object):
+  # missing associated documentation comment in .proto file
+  pass
+
+  def GetReference(self, request, context):
+    """Retrieve a CAS [Directory][build.bazel.remote.execution.v2.Directory]
+    digest by name.
+
+    Errors:
+    * `NOT_FOUND`: The requested reference is not in the cache.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def UpdateReference(self, request, context):
+    """Associate a name with a CAS [Directory][build.bazel.remote.execution.v2.Directory]
+    digest.
+
+    Errors:
+    * `RESOURCE_EXHAUSTED`: There is insufficient storage space to add the
+    entry to the cache.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def Status(self, request, context):
+    # missing associated documentation comment in .proto file
+    pass
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ReferenceStorageServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'GetReference': grpc.unary_unary_rpc_method_handler(
+          servicer.GetReference,
+          request_deserializer=buildstream_dot_v2_dot_buildstream__pb2.GetReferenceRequest.FromString,
+          response_serializer=buildstream_dot_v2_dot_buildstream__pb2.GetReferenceResponse.SerializeToString,
+      ),
+      'UpdateReference': grpc.unary_unary_rpc_method_handler(
+          servicer.UpdateReference,
+          request_deserializer=buildstream_dot_v2_dot_buildstream__pb2.UpdateReferenceRequest.FromString,
+          response_serializer=buildstream_dot_v2_dot_buildstream__pb2.UpdateReferenceResponse.SerializeToString,
+      ),
+      'Status': grpc.unary_unary_rpc_method_handler(
+          servicer.Status,
+          request_deserializer=buildstream_dot_v2_dot_buildstream__pb2.StatusRequest.FromString,
+          response_serializer=buildstream_dot_v2_dot_buildstream__pb2.StatusResponse.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'buildstream.v2.ReferenceStorage', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/src/buildstream/_protos/google/__init__.py b/src/buildstream/_protos/google/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/google/__init__.py
diff --git a/src/buildstream/_protos/google/api/__init__.py b/src/buildstream/_protos/google/api/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/google/api/__init__.py
diff --git a/src/buildstream/_protos/google/api/annotations.proto b/src/buildstream/_protos/google/api/annotations.proto
new file mode 100644
index 000000000..85c361b47
--- /dev/null
+++ b/src/buildstream/_protos/google/api/annotations.proto
@@ -0,0 +1,31 @@
+// Copyright (c) 2015, Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+import "google/api/http.proto";
+import "google/protobuf/descriptor.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "AnnotationsProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+extend google.protobuf.MethodOptions {
+  // See `HttpRule`.
+  HttpRule http = 72295728;
+}
diff --git a/src/buildstream/_protos/google/api/annotations_pb2.py b/src/buildstream/_protos/google/api/annotations_pb2.py
new file mode 100644
index 000000000..092c46de7
--- /dev/null
+++ b/src/buildstream/_protos/google/api/annotations_pb2.py
@@ -0,0 +1,46 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/api/annotations.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.google.api import http_pb2 as google_dot_api_dot_http__pb2
+from google.protobuf import descriptor_pb2 as google_dot_protobuf_dot_descriptor__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/api/annotations.proto',
+  package='google.api',
+  syntax='proto3',
+  serialized_pb=_b('\n\x1cgoogle/api/annotations.proto\x12\ngoogle.api\x1a\x15google/api/http.proto\x1a google/protobuf/descriptor.proto:E\n\x04http\x12\x1e.google.protobuf.MethodOptions\x18\xb0\xca\xbc\" \x01(\x0b\x32\x14.google.api.HttpRuleBn\n\x0e\x63om.google.apiB\x10\x41nnotationsProtoP\x01ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\xa2\x02\x04GAPIb\x06proto3')
+  ,
+  dependencies=[google_dot_api_dot_http__pb2.DESCRIPTOR,google_dot_protobuf_dot_descriptor__pb2.DESCRIPTOR,])
+
+
+HTTP_FIELD_NUMBER = 72295728
+http = _descriptor.FieldDescriptor(
+  name='http', full_name='google.api.http', index=0,
+  number=72295728, type=11, cpp_type=10, label=1,
+  has_default_value=False, default_value=None,
+  message_type=None, enum_type=None, containing_type=None,
+  is_extension=True, extension_scope=None,
+  options=None, file=DESCRIPTOR)
+
+DESCRIPTOR.extensions_by_name['http'] = http
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+http.message_type = google_dot_api_dot_http__pb2._HTTPRULE
+google_dot_protobuf_dot_descriptor__pb2.MethodOptions.RegisterExtension(http)
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\016com.google.apiB\020AnnotationsProtoP\001ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\242\002\004GAPI'))
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/google/api/annotations_pb2_grpc.py b/src/buildstream/_protos/google/api/annotations_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/src/buildstream/_protos/google/api/annotations_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
diff --git a/src/buildstream/_protos/google/api/http.proto b/src/buildstream/_protos/google/api/http.proto
new file mode 100644
index 000000000..78d515d4b
--- /dev/null
+++ b/src/buildstream/_protos/google/api/http.proto
@@ -0,0 +1,313 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+option cc_enable_arenas = true;
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "HttpProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+
+// Defines the HTTP configuration for an API service. It contains a list of
+// [HttpRule][google.api.HttpRule], each specifying the mapping of an RPC method
+// to one or more HTTP REST API methods.
+message Http {
+  // A list of HTTP configuration rules that apply to individual API methods.
+  //
+  // **NOTE:** All service configuration rules follow "last one wins" order.
+  repeated HttpRule rules = 1;
+
+  // When set to true, URL path parmeters will be fully URI-decoded except in
+  // cases of single segment matches in reserved expansion, where "%2F" will be
+  // left encoded.
+  //
+  // The default behavior is to not decode RFC 6570 reserved characters in multi
+  // segment matches.
+  bool fully_decode_reserved_expansion = 2;
+}
+
+// `HttpRule` defines the mapping of an RPC method to one or more HTTP
+// REST API methods. The mapping specifies how different portions of the RPC
+// request message are mapped to URL path, URL query parameters, and
+// HTTP request body. The mapping is typically specified as an
+// `google.api.http` annotation on the RPC method,
+// see "google/api/annotations.proto" for details.
+//
+// The mapping consists of a field specifying the path template and
+// method kind.  The path template can refer to fields in the request
+// message, as in the example below which describes a REST GET
+// operation on a resource collection of messages:
+//
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http).get = "/v1/messages/{message_id}/{sub.subfield}";
+//       }
+//     }
+//     message GetMessageRequest {
+//       message SubMessage {
+//         string subfield = 1;
+//       }
+//       string message_id = 1; // mapped to the URL
+//       SubMessage sub = 2;    // `sub.subfield` is url-mapped
+//     }
+//     message Message {
+//       string text = 1; // content of the resource
+//     }
+//
+// The same http annotation can alternatively be expressed inside the
+// `GRPC API Configuration` YAML file.
+//
+//     http:
+//       rules:
+//         - selector: <proto_package_name>.Messaging.GetMessage
+//           get: /v1/messages/{message_id}/{sub.subfield}
+//
+// This definition enables an automatic, bidrectional mapping of HTTP
+// JSON to RPC. Example:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456/foo`  | `GetMessage(message_id: "123456" sub: SubMessage(subfield: "foo"))`
+//
+// In general, not only fields but also field paths can be referenced
+// from a path pattern. Fields mapped to the path pattern cannot be
+// repeated and must have a primitive (non-message) type.
+//
+// Any fields in the request message which are not bound by the path
+// pattern automatically become (optional) HTTP query
+// parameters. Assume the following definition of the request message:
+//
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http).get = "/v1/messages/{message_id}";
+//       }
+//     }
+//     message GetMessageRequest {
+//       message SubMessage {
+//         string subfield = 1;
+//       }
+//       string message_id = 1; // mapped to the URL
+//       int64 revision = 2;    // becomes a parameter
+//       SubMessage sub = 3;    // `sub.subfield` becomes a parameter
+//     }
+//
+//
+// This enables a HTTP JSON to RPC mapping as below:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456?revision=2&sub.subfield=foo` | `GetMessage(message_id: "123456" revision: 2 sub: SubMessage(subfield: "foo"))`
+//
+// Note that fields which are mapped to HTTP parameters must have a
+// primitive type or a repeated primitive type. Message types are not
+// allowed. In the case of a repeated type, the parameter can be
+// repeated in the URL, as in `...?param=A&param=B`.
+//
+// For HTTP method kinds which allow a request body, the `body` field
+// specifies the mapping. Consider a REST update method on the
+// message resource collection:
+//
+//
+//     service Messaging {
+//       rpc UpdateMessage(UpdateMessageRequest) returns (Message) {
+//         option (google.api.http) = {
+//           put: "/v1/messages/{message_id}"
+//           body: "message"
+//         };
+//       }
+//     }
+//     message UpdateMessageRequest {
+//       string message_id = 1; // mapped to the URL
+//       Message message = 2;   // mapped to the body
+//     }
+//
+//
+// The following HTTP JSON to RPC mapping is enabled, where the
+// representation of the JSON in the request body is determined by
+// protos JSON encoding:
+//
+// HTTP | RPC
+// -----|-----
+// `PUT /v1/messages/123456 { "text": "Hi!" }` | `UpdateMessage(message_id: "123456" message { text: "Hi!" })`
+//
+// The special name `*` can be used in the body mapping to define that
+// every field not bound by the path template should be mapped to the
+// request body.  This enables the following alternative definition of
+// the update method:
+//
+//     service Messaging {
+//       rpc UpdateMessage(Message) returns (Message) {
+//         option (google.api.http) = {
+//           put: "/v1/messages/{message_id}"
+//           body: "*"
+//         };
+//       }
+//     }
+//     message Message {
+//       string message_id = 1;
+//       string text = 2;
+//     }
+//
+//
+// The following HTTP JSON to RPC mapping is enabled:
+//
+// HTTP | RPC
+// -----|-----
+// `PUT /v1/messages/123456 { "text": "Hi!" }` | `UpdateMessage(message_id: "123456" text: "Hi!")`
+//
+// Note that when using `*` in the body mapping, it is not possible to
+// have HTTP parameters, as all fields not bound by the path end in
+// the body. This makes this option more rarely used in practice of
+// defining REST APIs. The common usage of `*` is in custom methods
+// which don't use the URL at all for transferring data.
+//
+// It is possible to define multiple HTTP methods for one RPC by using
+// the `additional_bindings` option. Example:
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http) = {
+//           get: "/v1/messages/{message_id}"
+//           additional_bindings {
+//             get: "/v1/users/{user_id}/messages/{message_id}"
+//           }
+//         };
+//       }
+//     }
+//     message GetMessageRequest {
+//       string message_id = 1;
+//       string user_id = 2;
+//     }
+//
+//
+// This enables the following two alternative HTTP JSON to RPC
+// mappings:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456` | `GetMessage(message_id: "123456")`
+// `GET /v1/users/me/messages/123456` | `GetMessage(user_id: "me" message_id: "123456")`
+//
+// # Rules for HTTP mapping
+//
+// The rules for mapping HTTP path, query parameters, and body fields
+// to the request message are as follows:
+//
+// 1. The `body` field specifies either `*` or a field path, or is
+//    omitted. If omitted, it indicates there is no HTTP request body.
+// 2. Leaf fields (recursive expansion of nested messages in the
+//    request) can be classified into three types:
+//     (a) Matched in the URL template.
+//     (b) Covered by body (if body is `*`, everything except (a) fields;
+//         else everything under the body field)
+//     (c) All other fields.
+// 3. URL query parameters found in the HTTP request are mapped to (c) fields.
+// 4. Any body sent with an HTTP request can contain only (b) fields.
+//
+// The syntax of the path template is as follows:
+//
+//     Template = "/" Segments [ Verb ] ;
+//     Segments = Segment { "/" Segment } ;
+//     Segment  = "*" | "**" | LITERAL | Variable ;
+//     Variable = "{" FieldPath [ "=" Segments ] "}" ;
+//     FieldPath = IDENT { "." IDENT } ;
+//     Verb     = ":" LITERAL ;
+//
+// The syntax `*` matches a single path segment. The syntax `**` matches zero
+// or more path segments, which must be the last part of the path except the
+// `Verb`. The syntax `LITERAL` matches literal text in the path.
+//
+// The syntax `Variable` matches part of the URL path as specified by its
+// template. A variable template must not contain other variables. If a variable
+// matches a single path segment, its template may be omitted, e.g. `{var}`
+// is equivalent to `{var=*}`.
+//
+// If a variable contains exactly one path segment, such as `"{var}"` or
+// `"{var=*}"`, when such a variable is expanded into a URL path, all characters
+// except `[-_.~0-9a-zA-Z]` are percent-encoded. Such variables show up in the
+// Discovery Document as `{var}`.
+//
+// If a variable contains one or more path segments, such as `"{var=foo/*}"`
+// or `"{var=**}"`, when such a variable is expanded into a URL path, all
+// characters except `[-_.~/0-9a-zA-Z]` are percent-encoded. Such variables
+// show up in the Discovery Document as `{+var}`.
+//
+// NOTE: While the single segment variable matches the semantics of
+// [RFC 6570](https://tools.ietf.org/html/rfc6570) Section 3.2.2
+// Simple String Expansion, the multi segment variable **does not** match
+// RFC 6570 Reserved Expansion. The reason is that the Reserved Expansion
+// does not expand special characters like `?` and `#`, which would lead
+// to invalid URLs.
+//
+// NOTE: the field paths in variables and in the `body` must not refer to
+// repeated fields or map fields.
+message HttpRule {
+  // Selects methods to which this rule applies.
+  //
+  // Refer to [selector][google.api.DocumentationRule.selector] for syntax details.
+  string selector = 1;
+
+  // Determines the URL pattern is matched by this rules. This pattern can be
+  // used with any of the {get|put|post|delete|patch} methods. A custom method
+  // can be defined using the 'custom' field.
+  oneof pattern {
+    // Used for listing and getting information about resources.
+    string get = 2;
+
+    // Used for updating a resource.
+    string put = 3;
+
+    // Used for creating a resource.
+    string post = 4;
+
+    // Used for deleting a resource.
+    string delete = 5;
+
+    // Used for updating a resource.
+    string patch = 6;
+
+    // The custom pattern is used for specifying an HTTP method that is not
+    // included in the `pattern` field, such as HEAD, or "*" to leave the
+    // HTTP method unspecified for this rule. The wild-card rule is useful
+    // for services that provide content to Web (HTML) clients.
+    CustomHttpPattern custom = 8;
+  }
+
+  // The name of the request field whose value is mapped to the HTTP body, or
+  // `*` for mapping all fields not captured by the path pattern to the HTTP
+  // body. NOTE: the referred field must not be a repeated field and must be
+  // present at the top-level of request message type.
+  string body = 7;
+
+  // Additional HTTP bindings for the selector. Nested bindings must
+  // not contain an `additional_bindings` field themselves (that is,
+  // the nesting may only be one level deep).
+  repeated HttpRule additional_bindings = 11;
+}
+
+// A custom pattern is used for defining custom HTTP verb.
+message CustomHttpPattern {
+  // The name of this custom HTTP verb.
+  string kind = 1;
+
+  // The path matched by this custom verb.
+  string path = 2;
+}
diff --git a/src/buildstream/_protos/google/api/http_pb2.py b/src/buildstream/_protos/google/api/http_pb2.py
new file mode 100644
index 000000000..aad9ddb97
--- /dev/null
+++ b/src/buildstream/_protos/google/api/http_pb2.py
@@ -0,0 +1,243 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/api/http.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/api/http.proto',
+  package='google.api',
+  syntax='proto3',
+  serialized_pb=_b('\n\x15google/api/http.proto\x12\ngoogle.api\"T\n\x04Http\x12#\n\x05rules\x18\x01 \x03(\x0b\x32\x14.google.api.HttpRule\x12\'\n\x1f\x66ully_decode_reserved_expansion\x18\x02 \x01(\x08\"\xea\x01\n\x08HttpRule\x12\x10\n\x08selector\x18\x01 \x01(\t\x12\r\n\x03get\x18\x02 \x01(\tH\x00\x12\r\n\x03put\x18\x03 \x01(\tH\x00\x12\x0e\n\x04post\x18\x04 \x01(\tH\x00\x12\x10\n\x06\x64\x65lete\x18\x05 \x01(\tH\x00\x12\x0f\n\x05patch\x18\x06 \x01(\tH\x00\x12/\n\x06\x63ustom\x18\x08 \x01(\x0b\x32\x1d.google.api.CustomHttpPatternH\x00\x12\x0c\n\x04\x62ody\x18\x07 \x01(\t\x12\x31\n\x13\x61\x64\x64itional_bindings\x18\x0b \x03(\x0b\x32\x14.google.api.HttpRuleB\t\n\x07pattern\"/\n\x11\x43ustomHttpPattern\x12\x0c\n\x04kind\x18\x01 \x01(\t\x12\x0c\n\x04path\x18\x02 \x01(\tBj\n\x0e\x63om.google.apiB\tHttpProtoP\x01ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\xf8\x01\x01\xa2\x02\x04GAPIb\x06proto3')
+)
+
+
+
+
+_HTTP = _descriptor.Descriptor(
+  name='Http',
+  full_name='google.api.Http',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='rules', full_name='google.api.Http.rules', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='fully_decode_reserved_expansion', full_name='google.api.Http.fully_decode_reserved_expansion', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=37,
+  serialized_end=121,
+)
+
+
+_HTTPRULE = _descriptor.Descriptor(
+  name='HttpRule',
+  full_name='google.api.HttpRule',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='selector', full_name='google.api.HttpRule.selector', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='get', full_name='google.api.HttpRule.get', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='put', full_name='google.api.HttpRule.put', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='post', full_name='google.api.HttpRule.post', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='delete', full_name='google.api.HttpRule.delete', index=4,
+      number=5, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='patch', full_name='google.api.HttpRule.patch', index=5,
+      number=6, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='custom', full_name='google.api.HttpRule.custom', index=6,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='body', full_name='google.api.HttpRule.body', index=7,
+      number=7, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='additional_bindings', full_name='google.api.HttpRule.additional_bindings', index=8,
+      number=11, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+    _descriptor.OneofDescriptor(
+      name='pattern', full_name='google.api.HttpRule.pattern',
+      index=0, containing_type=None, fields=[]),
+  ],
+  serialized_start=124,
+  serialized_end=358,
+)
+
+
+_CUSTOMHTTPPATTERN = _descriptor.Descriptor(
+  name='CustomHttpPattern',
+  full_name='google.api.CustomHttpPattern',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='kind', full_name='google.api.CustomHttpPattern.kind', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='path', full_name='google.api.CustomHttpPattern.path', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=360,
+  serialized_end=407,
+)
+
+_HTTP.fields_by_name['rules'].message_type = _HTTPRULE
+_HTTPRULE.fields_by_name['custom'].message_type = _CUSTOMHTTPPATTERN
+_HTTPRULE.fields_by_name['additional_bindings'].message_type = _HTTPRULE
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['get'])
+_HTTPRULE.fields_by_name['get'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['put'])
+_HTTPRULE.fields_by_name['put'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['post'])
+_HTTPRULE.fields_by_name['post'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['delete'])
+_HTTPRULE.fields_by_name['delete'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['patch'])
+_HTTPRULE.fields_by_name['patch'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['custom'])
+_HTTPRULE.fields_by_name['custom'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+DESCRIPTOR.message_types_by_name['Http'] = _HTTP
+DESCRIPTOR.message_types_by_name['HttpRule'] = _HTTPRULE
+DESCRIPTOR.message_types_by_name['CustomHttpPattern'] = _CUSTOMHTTPPATTERN
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Http = _reflection.GeneratedProtocolMessageType('Http', (_message.Message,), dict(
+  DESCRIPTOR = _HTTP,
+  __module__ = 'google.api.http_pb2'
+  # @@protoc_insertion_point(class_scope:google.api.Http)
+  ))
+_sym_db.RegisterMessage(Http)
+
+HttpRule = _reflection.GeneratedProtocolMessageType('HttpRule', (_message.Message,), dict(
+  DESCRIPTOR = _HTTPRULE,
+  __module__ = 'google.api.http_pb2'
+  # @@protoc_insertion_point(class_scope:google.api.HttpRule)
+  ))
+_sym_db.RegisterMessage(HttpRule)
+
+CustomHttpPattern = _reflection.GeneratedProtocolMessageType('CustomHttpPattern', (_message.Message,), dict(
+  DESCRIPTOR = _CUSTOMHTTPPATTERN,
+  __module__ = 'google.api.http_pb2'
+  # @@protoc_insertion_point(class_scope:google.api.CustomHttpPattern)
+  ))
+_sym_db.RegisterMessage(CustomHttpPattern)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\016com.google.apiB\tHttpProtoP\001ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\370\001\001\242\002\004GAPI'))
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/google/api/http_pb2_grpc.py b/src/buildstream/_protos/google/api/http_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/src/buildstream/_protos/google/api/http_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
diff --git a/src/buildstream/_protos/google/bytestream/__init__.py b/src/buildstream/_protos/google/bytestream/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/google/bytestream/__init__.py
diff --git a/src/buildstream/_protos/google/bytestream/bytestream.proto b/src/buildstream/_protos/google/bytestream/bytestream.proto
new file mode 100644
index 000000000..85e386fc2
--- /dev/null
+++ b/src/buildstream/_protos/google/bytestream/bytestream.proto
@@ -0,0 +1,181 @@
+// Copyright 2016 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.bytestream;
+
+import "google/api/annotations.proto";
+import "google/protobuf/wrappers.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/bytestream;bytestream";
+option java_outer_classname = "ByteStreamProto";
+option java_package = "com.google.bytestream";
+
+
+// #### Introduction
+//
+// The Byte Stream API enables a client to read and write a stream of bytes to
+// and from a resource. Resources have names, and these names are supplied in
+// the API calls below to identify the resource that is being read from or
+// written to.
+//
+// All implementations of the Byte Stream API export the interface defined here:
+//
+// * `Read()`: Reads the contents of a resource.
+//
+// * `Write()`: Writes the contents of a resource. The client can call `Write()`
+//   multiple times with the same resource and can check the status of the write
+//   by calling `QueryWriteStatus()`.
+//
+// #### Service parameters and metadata
+//
+// The ByteStream API provides no direct way to access/modify any metadata
+// associated with the resource.
+//
+// #### Errors
+//
+// The errors returned by the service are in the Google canonical error space.
+service ByteStream {
+  // `Read()` is used to retrieve the contents of a resource as a sequence
+  // of bytes. The bytes are returned in a sequence of responses, and the
+  // responses are delivered as the results of a server-side streaming RPC.
+  rpc Read(ReadRequest) returns (stream ReadResponse);
+
+  // `Write()` is used to send the contents of a resource as a sequence of
+  // bytes. The bytes are sent in a sequence of request protos of a client-side
+  // streaming RPC.
+  //
+  // A `Write()` action is resumable. If there is an error or the connection is
+  // broken during the `Write()`, the client should check the status of the
+  // `Write()` by calling `QueryWriteStatus()` and continue writing from the
+  // returned `committed_size`. This may be less than the amount of data the
+  // client previously sent.
+  //
+  // Calling `Write()` on a resource name that was previously written and
+  // finalized could cause an error, depending on whether the underlying service
+  // allows over-writing of previously written resources.
+  //
+  // When the client closes the request channel, the service will respond with
+  // a `WriteResponse`. The service will not view the resource as `complete`
+  // until the client has sent a `WriteRequest` with `finish_write` set to
+  // `true`. Sending any requests on a stream after sending a request with
+  // `finish_write` set to `true` will cause an error. The client **should**
+  // check the `WriteResponse` it receives to determine how much data the
+  // service was able to commit and whether the service views the resource as
+  // `complete` or not.
+  rpc Write(stream WriteRequest) returns (WriteResponse);
+
+  // `QueryWriteStatus()` is used to find the `committed_size` for a resource
+  // that is being written, which can then be used as the `write_offset` for
+  // the next `Write()` call.
+  //
+  // If the resource does not exist (i.e., the resource has been deleted, or the
+  // first `Write()` has not yet reached the service), this method returns the
+  // error `NOT_FOUND`.
+  //
+  // The client **may** call `QueryWriteStatus()` at any time to determine how
+  // much data has been processed for this resource. This is useful if the
+  // client is buffering data and needs to know which data can be safely
+  // evicted. For any sequence of `QueryWriteStatus()` calls for a given
+  // resource name, the sequence of returned `committed_size` values will be
+  // non-decreasing.
+  rpc QueryWriteStatus(QueryWriteStatusRequest) returns (QueryWriteStatusResponse);
+}
+
+// Request object for ByteStream.Read.
+message ReadRequest {
+  // The name of the resource to read.
+  string resource_name = 1;
+
+  // The offset for the first byte to return in the read, relative to the start
+  // of the resource.
+  //
+  // A `read_offset` that is negative or greater than the size of the resource
+  // will cause an `OUT_OF_RANGE` error.
+  int64 read_offset = 2;
+
+  // The maximum number of `data` bytes the server is allowed to return in the
+  // sum of all `ReadResponse` messages. A `read_limit` of zero indicates that
+  // there is no limit, and a negative `read_limit` will cause an error.
+  //
+  // If the stream returns fewer bytes than allowed by the `read_limit` and no
+  // error occurred, the stream includes all data from the `read_offset` to the
+  // end of the resource.
+  int64 read_limit = 3;
+}
+
+// Response object for ByteStream.Read.
+message ReadResponse {
+  // A portion of the data for the resource. The service **may** leave `data`
+  // empty for any given `ReadResponse`. This enables the service to inform the
+  // client that the request is still live while it is running an operation to
+  // generate more data.
+  bytes data = 10;
+}
+
+// Request object for ByteStream.Write.
+message WriteRequest {
+  // The name of the resource to write. This **must** be set on the first
+  // `WriteRequest` of each `Write()` action. If it is set on subsequent calls,
+  // it **must** match the value of the first request.
+  string resource_name = 1;
+
+  // The offset from the beginning of the resource at which the data should be
+  // written. It is required on all `WriteRequest`s.
+  //
+  // In the first `WriteRequest` of a `Write()` action, it indicates
+  // the initial offset for the `Write()` call. The value **must** be equal to
+  // the `committed_size` that a call to `QueryWriteStatus()` would return.
+  //
+  // On subsequent calls, this value **must** be set and **must** be equal to
+  // the sum of the first `write_offset` and the sizes of all `data` bundles
+  // sent previously on this stream.
+  //
+  // An incorrect value will cause an error.
+  int64 write_offset = 2;
+
+  // If `true`, this indicates that the write is complete. Sending any
+  // `WriteRequest`s subsequent to one in which `finish_write` is `true` will
+  // cause an error.
+  bool finish_write = 3;
+
+  // A portion of the data for the resource. The client **may** leave `data`
+  // empty for any given `WriteRequest`. This enables the client to inform the
+  // service that the request is still live while it is running an operation to
+  // generate more data.
+  bytes data = 10;
+}
+
+// Response object for ByteStream.Write.
+message WriteResponse {
+  // The number of bytes that have been processed for the given resource.
+  int64 committed_size = 1;
+}
+
+// Request object for ByteStream.QueryWriteStatus.
+message QueryWriteStatusRequest {
+  // The name of the resource whose write status is being requested.
+  string resource_name = 1;
+}
+
+// Response object for ByteStream.QueryWriteStatus.
+message QueryWriteStatusResponse {
+  // The number of bytes that have been processed for the given resource.
+  int64 committed_size = 1;
+
+  // `complete` is `true` only if the client has sent a `WriteRequest` with
+  // `finish_write` set to true, and the server has processed that request.
+  bool complete = 2;
+}
diff --git a/src/buildstream/_protos/google/bytestream/bytestream_pb2.py b/src/buildstream/_protos/google/bytestream/bytestream_pb2.py
new file mode 100644
index 000000000..c8487d6a0
--- /dev/null
+++ b/src/buildstream/_protos/google/bytestream/bytestream_pb2.py
@@ -0,0 +1,353 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/bytestream/bytestream.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+from google.protobuf import wrappers_pb2 as google_dot_protobuf_dot_wrappers__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/bytestream/bytestream.proto',
+  package='google.bytestream',
+  syntax='proto3',
+  serialized_pb=_b('\n\"google/bytestream/bytestream.proto\x12\x11google.bytestream\x1a\x1cgoogle/api/annotations.proto\x1a\x1egoogle/protobuf/wrappers.proto\"M\n\x0bReadRequest\x12\x15\n\rresource_name\x18\x01 \x01(\t\x12\x13\n\x0bread_offset\x18\x02 \x01(\x03\x12\x12\n\nread_limit\x18\x03 \x01(\x03\"\x1c\n\x0cReadResponse\x12\x0c\n\x04\x64\x61ta\x18\n \x01(\x0c\"_\n\x0cWriteRequest\x12\x15\n\rresource_name\x18\x01 \x01(\t\x12\x14\n\x0cwrite_offset\x18\x02 \x01(\x03\x12\x14\n\x0c\x66inish_write\x18\x03 \x01(\x08\x12\x0c\n\x04\x64\x61ta\x18\n \x01(\x0c\"\'\n\rWriteResponse\x12\x16\n\x0e\x63ommitted_size\x18\x01 \x01(\x03\"0\n\x17QueryWriteStatusRequest\x12\x15\n\rresource_name\x18\x01 \x01(\t\"D\n\x18QueryWriteStatusResponse\x12\x16\n\x0e\x63ommitted_size\x18\x01 \x01(\x03\x12\x10\n\x08\x63omplete\x18\x02 \x01(\x08\x32\x92\x02\n\nByteStream\x12I\n\x04Read\x12\x1e.google.bytestream.ReadRequest\x1a\x1f.google.bytestream.ReadResponse0\x01\x12L\n\x05Write\x12\x1f.google.bytestream.WriteRequest\x1a .google.bytestream.WriteResponse(\x01\x12k\n\x10QueryWriteStatus\x12*.google.bytestream.QueryWriteStatusRequest\x1a+.google.bytestream.QueryWriteStatusResponseBe\n\x15\x63om.google.bytestreamB\x0f\x42yteStreamProtoZ;google.golang.org/genproto/googleapis/bytestream;bytestreamb\x06proto3')
+  ,
+  dependencies=[google_dot_api_dot_annotations__pb2.DESCRIPTOR,google_dot_protobuf_dot_wrappers__pb2.DESCRIPTOR,])
+
+
+
+
+_READREQUEST = _descriptor.Descriptor(
+  name='ReadRequest',
+  full_name='google.bytestream.ReadRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='resource_name', full_name='google.bytestream.ReadRequest.resource_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='read_offset', full_name='google.bytestream.ReadRequest.read_offset', index=1,
+      number=2, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='read_limit', full_name='google.bytestream.ReadRequest.read_limit', index=2,
+      number=3, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=119,
+  serialized_end=196,
+)
+
+
+_READRESPONSE = _descriptor.Descriptor(
+  name='ReadResponse',
+  full_name='google.bytestream.ReadResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='data', full_name='google.bytestream.ReadResponse.data', index=0,
+      number=10, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=198,
+  serialized_end=226,
+)
+
+
+_WRITEREQUEST = _descriptor.Descriptor(
+  name='WriteRequest',
+  full_name='google.bytestream.WriteRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='resource_name', full_name='google.bytestream.WriteRequest.resource_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='write_offset', full_name='google.bytestream.WriteRequest.write_offset', index=1,
+      number=2, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='finish_write', full_name='google.bytestream.WriteRequest.finish_write', index=2,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='data', full_name='google.bytestream.WriteRequest.data', index=3,
+      number=10, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=228,
+  serialized_end=323,
+)
+
+
+_WRITERESPONSE = _descriptor.Descriptor(
+  name='WriteResponse',
+  full_name='google.bytestream.WriteResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='committed_size', full_name='google.bytestream.WriteResponse.committed_size', index=0,
+      number=1, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=325,
+  serialized_end=364,
+)
+
+
+_QUERYWRITESTATUSREQUEST = _descriptor.Descriptor(
+  name='QueryWriteStatusRequest',
+  full_name='google.bytestream.QueryWriteStatusRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='resource_name', full_name='google.bytestream.QueryWriteStatusRequest.resource_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=366,
+  serialized_end=414,
+)
+
+
+_QUERYWRITESTATUSRESPONSE = _descriptor.Descriptor(
+  name='QueryWriteStatusResponse',
+  full_name='google.bytestream.QueryWriteStatusResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='committed_size', full_name='google.bytestream.QueryWriteStatusResponse.committed_size', index=0,
+      number=1, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='complete', full_name='google.bytestream.QueryWriteStatusResponse.complete', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=416,
+  serialized_end=484,
+)
+
+DESCRIPTOR.message_types_by_name['ReadRequest'] = _READREQUEST
+DESCRIPTOR.message_types_by_name['ReadResponse'] = _READRESPONSE
+DESCRIPTOR.message_types_by_name['WriteRequest'] = _WRITEREQUEST
+DESCRIPTOR.message_types_by_name['WriteResponse'] = _WRITERESPONSE
+DESCRIPTOR.message_types_by_name['QueryWriteStatusRequest'] = _QUERYWRITESTATUSREQUEST
+DESCRIPTOR.message_types_by_name['QueryWriteStatusResponse'] = _QUERYWRITESTATUSRESPONSE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+ReadRequest = _reflection.GeneratedProtocolMessageType('ReadRequest', (_message.Message,), dict(
+  DESCRIPTOR = _READREQUEST,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.ReadRequest)
+  ))
+_sym_db.RegisterMessage(ReadRequest)
+
+ReadResponse = _reflection.GeneratedProtocolMessageType('ReadResponse', (_message.Message,), dict(
+  DESCRIPTOR = _READRESPONSE,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.ReadResponse)
+  ))
+_sym_db.RegisterMessage(ReadResponse)
+
+WriteRequest = _reflection.GeneratedProtocolMessageType('WriteRequest', (_message.Message,), dict(
+  DESCRIPTOR = _WRITEREQUEST,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.WriteRequest)
+  ))
+_sym_db.RegisterMessage(WriteRequest)
+
+WriteResponse = _reflection.GeneratedProtocolMessageType('WriteResponse', (_message.Message,), dict(
+  DESCRIPTOR = _WRITERESPONSE,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.WriteResponse)
+  ))
+_sym_db.RegisterMessage(WriteResponse)
+
+QueryWriteStatusRequest = _reflection.GeneratedProtocolMessageType('QueryWriteStatusRequest', (_message.Message,), dict(
+  DESCRIPTOR = _QUERYWRITESTATUSREQUEST,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.QueryWriteStatusRequest)
+  ))
+_sym_db.RegisterMessage(QueryWriteStatusRequest)
+
+QueryWriteStatusResponse = _reflection.GeneratedProtocolMessageType('QueryWriteStatusResponse', (_message.Message,), dict(
+  DESCRIPTOR = _QUERYWRITESTATUSRESPONSE,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.QueryWriteStatusResponse)
+  ))
+_sym_db.RegisterMessage(QueryWriteStatusResponse)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\025com.google.bytestreamB\017ByteStreamProtoZ;google.golang.org/genproto/googleapis/bytestream;bytestream'))
+
+_BYTESTREAM = _descriptor.ServiceDescriptor(
+  name='ByteStream',
+  full_name='google.bytestream.ByteStream',
+  file=DESCRIPTOR,
+  index=0,
+  options=None,
+  serialized_start=487,
+  serialized_end=761,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='Read',
+    full_name='google.bytestream.ByteStream.Read',
+    index=0,
+    containing_service=None,
+    input_type=_READREQUEST,
+    output_type=_READRESPONSE,
+    options=None,
+  ),
+  _descriptor.MethodDescriptor(
+    name='Write',
+    full_name='google.bytestream.ByteStream.Write',
+    index=1,
+    containing_service=None,
+    input_type=_WRITEREQUEST,
+    output_type=_WRITERESPONSE,
+    options=None,
+  ),
+  _descriptor.MethodDescriptor(
+    name='QueryWriteStatus',
+    full_name='google.bytestream.ByteStream.QueryWriteStatus',
+    index=2,
+    containing_service=None,
+    input_type=_QUERYWRITESTATUSREQUEST,
+    output_type=_QUERYWRITESTATUSRESPONSE,
+    options=None,
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_BYTESTREAM)
+
+DESCRIPTOR.services_by_name['ByteStream'] = _BYTESTREAM
+
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/google/bytestream/bytestream_pb2_grpc.py b/src/buildstream/_protos/google/bytestream/bytestream_pb2_grpc.py
new file mode 100644
index 000000000..ef993e040
--- /dev/null
+++ b/src/buildstream/_protos/google/bytestream/bytestream_pb2_grpc.py
@@ -0,0 +1,160 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.google.bytestream import bytestream_pb2 as google_dot_bytestream_dot_bytestream__pb2
+
+
+class ByteStreamStub(object):
+  """#### Introduction
+
+  The Byte Stream API enables a client to read and write a stream of bytes to
+  and from a resource. Resources have names, and these names are supplied in
+  the API calls below to identify the resource that is being read from or
+  written to.
+
+  All implementations of the Byte Stream API export the interface defined here:
+
+  * `Read()`: Reads the contents of a resource.
+
+  * `Write()`: Writes the contents of a resource. The client can call `Write()`
+  multiple times with the same resource and can check the status of the write
+  by calling `QueryWriteStatus()`.
+
+  #### Service parameters and metadata
+
+  The ByteStream API provides no direct way to access/modify any metadata
+  associated with the resource.
+
+  #### Errors
+
+  The errors returned by the service are in the Google canonical error space.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.Read = channel.unary_stream(
+        '/google.bytestream.ByteStream/Read',
+        request_serializer=google_dot_bytestream_dot_bytestream__pb2.ReadRequest.SerializeToString,
+        response_deserializer=google_dot_bytestream_dot_bytestream__pb2.ReadResponse.FromString,
+        )
+    self.Write = channel.stream_unary(
+        '/google.bytestream.ByteStream/Write',
+        request_serializer=google_dot_bytestream_dot_bytestream__pb2.WriteRequest.SerializeToString,
+        response_deserializer=google_dot_bytestream_dot_bytestream__pb2.WriteResponse.FromString,
+        )
+    self.QueryWriteStatus = channel.unary_unary(
+        '/google.bytestream.ByteStream/QueryWriteStatus',
+        request_serializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusRequest.SerializeToString,
+        response_deserializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusResponse.FromString,
+        )
+
+
+class ByteStreamServicer(object):
+  """#### Introduction
+
+  The Byte Stream API enables a client to read and write a stream of bytes to
+  and from a resource. Resources have names, and these names are supplied in
+  the API calls below to identify the resource that is being read from or
+  written to.
+
+  All implementations of the Byte Stream API export the interface defined here:
+
+  * `Read()`: Reads the contents of a resource.
+
+  * `Write()`: Writes the contents of a resource. The client can call `Write()`
+  multiple times with the same resource and can check the status of the write
+  by calling `QueryWriteStatus()`.
+
+  #### Service parameters and metadata
+
+  The ByteStream API provides no direct way to access/modify any metadata
+  associated with the resource.
+
+  #### Errors
+
+  The errors returned by the service are in the Google canonical error space.
+  """
+
+  def Read(self, request, context):
+    """`Read()` is used to retrieve the contents of a resource as a sequence
+    of bytes. The bytes are returned in a sequence of responses, and the
+    responses are delivered as the results of a server-side streaming RPC.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def Write(self, request_iterator, context):
+    """`Write()` is used to send the contents of a resource as a sequence of
+    bytes. The bytes are sent in a sequence of request protos of a client-side
+    streaming RPC.
+
+    A `Write()` action is resumable. If there is an error or the connection is
+    broken during the `Write()`, the client should check the status of the
+    `Write()` by calling `QueryWriteStatus()` and continue writing from the
+    returned `committed_size`. This may be less than the amount of data the
+    client previously sent.
+
+    Calling `Write()` on a resource name that was previously written and
+    finalized could cause an error, depending on whether the underlying service
+    allows over-writing of previously written resources.
+
+    When the client closes the request channel, the service will respond with
+    a `WriteResponse`. The service will not view the resource as `complete`
+    until the client has sent a `WriteRequest` with `finish_write` set to
+    `true`. Sending any requests on a stream after sending a request with
+    `finish_write` set to `true` will cause an error. The client **should**
+    check the `WriteResponse` it receives to determine how much data the
+    service was able to commit and whether the service views the resource as
+    `complete` or not.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def QueryWriteStatus(self, request, context):
+    """`QueryWriteStatus()` is used to find the `committed_size` for a resource
+    that is being written, which can then be used as the `write_offset` for
+    the next `Write()` call.
+
+    If the resource does not exist (i.e., the resource has been deleted, or the
+    first `Write()` has not yet reached the service), this method returns the
+    error `NOT_FOUND`.
+
+    The client **may** call `QueryWriteStatus()` at any time to determine how
+    much data has been processed for this resource. This is useful if the
+    client is buffering data and needs to know which data can be safely
+    evicted. For any sequence of `QueryWriteStatus()` calls for a given
+    resource name, the sequence of returned `committed_size` values will be
+    non-decreasing.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ByteStreamServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'Read': grpc.unary_stream_rpc_method_handler(
+          servicer.Read,
+          request_deserializer=google_dot_bytestream_dot_bytestream__pb2.ReadRequest.FromString,
+          response_serializer=google_dot_bytestream_dot_bytestream__pb2.ReadResponse.SerializeToString,
+      ),
+      'Write': grpc.stream_unary_rpc_method_handler(
+          servicer.Write,
+          request_deserializer=google_dot_bytestream_dot_bytestream__pb2.WriteRequest.FromString,
+          response_serializer=google_dot_bytestream_dot_bytestream__pb2.WriteResponse.SerializeToString,
+      ),
+      'QueryWriteStatus': grpc.unary_unary_rpc_method_handler(
+          servicer.QueryWriteStatus,
+          request_deserializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusRequest.FromString,
+          response_serializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusResponse.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'google.bytestream.ByteStream', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/src/buildstream/_protos/google/longrunning/__init__.py b/src/buildstream/_protos/google/longrunning/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/google/longrunning/__init__.py
diff --git a/src/buildstream/_protos/google/longrunning/operations.proto b/src/buildstream/_protos/google/longrunning/operations.proto
new file mode 100644
index 000000000..76fef29c3
--- /dev/null
+++ b/src/buildstream/_protos/google/longrunning/operations.proto
@@ -0,0 +1,160 @@
+// Copyright 2016 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.longrunning;
+
+import "google/api/annotations.proto";
+import "google/protobuf/any.proto";
+import "google/protobuf/empty.proto";
+import "google/rpc/status.proto";
+
+option csharp_namespace = "Google.LongRunning";
+option go_package = "google.golang.org/genproto/googleapis/longrunning;longrunning";
+option java_multiple_files = true;
+option java_outer_classname = "OperationsProto";
+option java_package = "com.google.longrunning";
+option php_namespace = "Google\\LongRunning";
+
+
+// Manages long-running operations with an API service.
+//
+// When an API method normally takes long time to complete, it can be designed
+// to return [Operation][google.longrunning.Operation] to the client, and the client can use this
+// interface to receive the real response asynchronously by polling the
+// operation resource, or pass the operation resource to another API (such as
+// Google Cloud Pub/Sub API) to receive the response.  Any API service that
+// returns long-running operations should implement the `Operations` interface
+// so developers can have a consistent client experience.
+service Operations {
+  // Lists operations that match the specified filter in the request. If the
+  // server doesn't support this method, it returns `UNIMPLEMENTED`.
+  //
+  // NOTE: the `name` binding below allows API services to override the binding
+  // to use different resource name schemes, such as `users/*/operations`.
+  rpc ListOperations(ListOperationsRequest) returns (ListOperationsResponse) {
+    option (google.api.http) = { get: "/v1/{name=operations}" };
+  }
+
+  // Gets the latest state of a long-running operation.  Clients can use this
+  // method to poll the operation result at intervals as recommended by the API
+  // service.
+  rpc GetOperation(GetOperationRequest) returns (Operation) {
+    option (google.api.http) = { get: "/v1/{name=operations/**}" };
+  }
+
+  // Deletes a long-running operation. This method indicates that the client is
+  // no longer interested in the operation result. It does not cancel the
+  // operation. If the server doesn't support this method, it returns
+  // `google.rpc.Code.UNIMPLEMENTED`.
+  rpc DeleteOperation(DeleteOperationRequest) returns (google.protobuf.Empty) {
+    option (google.api.http) = { delete: "/v1/{name=operations/**}" };
+  }
+
+  // Starts asynchronous cancellation on a long-running operation.  The server
+  // makes a best effort to cancel the operation, but success is not
+  // guaranteed.  If the server doesn't support this method, it returns
+  // `google.rpc.Code.UNIMPLEMENTED`.  Clients can use
+  // [Operations.GetOperation][google.longrunning.Operations.GetOperation] or
+  // other methods to check whether the cancellation succeeded or whether the
+  // operation completed despite cancellation. On successful cancellation,
+  // the operation is not deleted; instead, it becomes an operation with
+  // an [Operation.error][google.longrunning.Operation.error] value with a [google.rpc.Status.code][google.rpc.Status.code] of 1,
+  // corresponding to `Code.CANCELLED`.
+  rpc CancelOperation(CancelOperationRequest) returns (google.protobuf.Empty) {
+    option (google.api.http) = { post: "/v1/{name=operations/**}:cancel" body: "*" };
+  }
+}
+
+// This resource represents a long-running operation that is the result of a
+// network API call.
+message Operation {
+  // The server-assigned name, which is only unique within the same service that
+  // originally returns it. If you use the default HTTP mapping, the
+  // `name` should have the format of `operations/some/unique/name`.
+  string name = 1;
+
+  // Service-specific metadata associated with the operation.  It typically
+  // contains progress information and common metadata such as create time.
+  // Some services might not provide such metadata.  Any method that returns a
+  // long-running operation should document the metadata type, if any.
+  google.protobuf.Any metadata = 2;
+
+  // If the value is `false`, it means the operation is still in progress.
+  // If true, the operation is completed, and either `error` or `response` is
+  // available.
+  bool done = 3;
+
+  // The operation result, which can be either an `error` or a valid `response`.
+  // If `done` == `false`, neither `error` nor `response` is set.
+  // If `done` == `true`, exactly one of `error` or `response` is set.
+  oneof result {
+    // The error result of the operation in case of failure or cancellation.
+    google.rpc.Status error = 4;
+
+    // The normal response of the operation in case of success.  If the original
+    // method returns no data on success, such as `Delete`, the response is
+    // `google.protobuf.Empty`.  If the original method is standard
+    // `Get`/`Create`/`Update`, the response should be the resource.  For other
+    // methods, the response should have the type `XxxResponse`, where `Xxx`
+    // is the original method name.  For example, if the original method name
+    // is `TakeSnapshot()`, the inferred response type is
+    // `TakeSnapshotResponse`.
+    google.protobuf.Any response = 5;
+  }
+}
+
+// The request message for [Operations.GetOperation][google.longrunning.Operations.GetOperation].
+message GetOperationRequest {
+  // The name of the operation resource.
+  string name = 1;
+}
+
+// The request message for [Operations.ListOperations][google.longrunning.Operations.ListOperations].
+message ListOperationsRequest {
+  // The name of the operation collection.
+  string name = 4;
+
+  // The standard list filter.
+  string filter = 1;
+
+  // The standard list page size.
+  int32 page_size = 2;
+
+  // The standard list page token.
+  string page_token = 3;
+}
+
+// The response message for [Operations.ListOperations][google.longrunning.Operations.ListOperations].
+message ListOperationsResponse {
+  // A list of operations that matches the specified filter in the request.
+  repeated Operation operations = 1;
+
+  // The standard List next-page token.
+  string next_page_token = 2;
+}
+
+// The request message for [Operations.CancelOperation][google.longrunning.Operations.CancelOperation].
+message CancelOperationRequest {
+  // The name of the operation resource to be cancelled.
+  string name = 1;
+}
+
+// The request message for [Operations.DeleteOperation][google.longrunning.Operations.DeleteOperation].
+message DeleteOperationRequest {
+  // The name of the operation resource to be deleted.
+  string name = 1;
+}
+
diff --git a/src/buildstream/_protos/google/longrunning/operations_pb2.py b/src/buildstream/_protos/google/longrunning/operations_pb2.py
new file mode 100644
index 000000000..9fd89937f
--- /dev/null
+++ b/src/buildstream/_protos/google/longrunning/operations_pb2.py
@@ -0,0 +1,391 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/longrunning/operations.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+from google.protobuf import any_pb2 as google_dot_protobuf_dot_any__pb2
+from google.protobuf import empty_pb2 as google_dot_protobuf_dot_empty__pb2
+from buildstream._protos.google.rpc import status_pb2 as google_dot_rpc_dot_status__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/longrunning/operations.proto',
+  package='google.longrunning',
+  syntax='proto3',
+  serialized_pb=_b('\n#google/longrunning/operations.proto\x12\x12google.longrunning\x1a\x1cgoogle/api/annotations.proto\x1a\x19google/protobuf/any.proto\x1a\x1bgoogle/protobuf/empty.proto\x1a\x17google/rpc/status.proto\"\xa8\x01\n\tOperation\x12\x0c\n\x04name\x18\x01 \x01(\t\x12&\n\x08metadata\x18\x02 \x01(\x0b\x32\x14.google.protobuf.Any\x12\x0c\n\x04\x64one\x18\x03 \x01(\x08\x12#\n\x05\x65rror\x18\x04 \x01(\x0b\x32\x12.google.rpc.StatusH\x00\x12(\n\x08response\x18\x05 \x01(\x0b\x32\x14.google.protobuf.AnyH\x00\x42\x08\n\x06result\"#\n\x13GetOperationRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"\\\n\x15ListOperationsRequest\x12\x0c\n\x04name\x18\x04 \x01(\t\x12\x0e\n\x06\x66ilter\x18\x01 \x01(\t\x12\x11\n\tpage_size\x18\x02 \x01(\x05\x12\x12\n\npage_token\x18\x03 \x01(\t\"d\n\x16ListOperationsResponse\x12\x31\n\noperations\x18\x01 \x03(\x0b\x32\x1d.google.longrunning.Operation\x12\x17\n\x0fnext_page_token\x18\x02 \x01(\t\"&\n\x16\x43\x61ncelOperationRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"&\n\x16\x44\x65leteOperationRequest\x12\x0c\n\x04name\x18\x01 \x01(\t2\x8c\x04\n\nOperations\x12\x86\x01\n\x0eListOperations\x12).google.longrunning.ListOperationsRequest\x1a*.google.longrunning.ListOperationsResponse\"\x1d\x82\xd3\xe4\x93\x02\x17\x12\x15/v1/{name=operations}\x12x\n\x0cGetOperation\x12\'.google.longrunning.GetOperationRequest\x1a\x1d.google.longrunning.Operation\" \x82\xd3\xe4\x93\x02\x1a\x12\x18/v1/{name=operations/**}\x12w\n\x0f\x44\x65leteOperation\x12*.google.longrunning.DeleteOperationRequest\x1a\x16.google.protobuf.Empty\" \x82\xd3\xe4\x93\x02\x1a*\x18/v1/{name=operations/**}\x12\x81\x01\n\x0f\x43\x61ncelOperation\x12*.google.longrunning.CancelOperationRequest\x1a\x16.google.protobuf.Empty\"*\x82\xd3\xe4\x93\x02$\"\x1f/v1/{name=operations/**}:cancel:\x01*B\x94\x01\n\x16\x63om.google.longrunningB\x0fOperationsProtoP\x01Z=google.golang.org/genproto/googleapis/longrunning;longrunning\xaa\x02\x12Google.LongRunning\xca\x02\x12Google\\LongRunningb\x06proto3')
+  ,
+  dependencies=[google_dot_api_dot_annotations__pb2.DESCRIPTOR,google_dot_protobuf_dot_any__pb2.DESCRIPTOR,google_dot_protobuf_dot_empty__pb2.DESCRIPTOR,google_dot_rpc_dot_status__pb2.DESCRIPTOR,])
+
+
+
+
+_OPERATION = _descriptor.Descriptor(
+  name='Operation',
+  full_name='google.longrunning.Operation',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.Operation.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='metadata', full_name='google.longrunning.Operation.metadata', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='done', full_name='google.longrunning.Operation.done', index=2,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='error', full_name='google.longrunning.Operation.error', index=3,
+      number=4, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='response', full_name='google.longrunning.Operation.response', index=4,
+      number=5, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+    _descriptor.OneofDescriptor(
+      name='result', full_name='google.longrunning.Operation.result',
+      index=0, containing_type=None, fields=[]),
+  ],
+  serialized_start=171,
+  serialized_end=339,
+)
+
+
+_GETOPERATIONREQUEST = _descriptor.Descriptor(
+  name='GetOperationRequest',
+  full_name='google.longrunning.GetOperationRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.GetOperationRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=341,
+  serialized_end=376,
+)
+
+
+_LISTOPERATIONSREQUEST = _descriptor.Descriptor(
+  name='ListOperationsRequest',
+  full_name='google.longrunning.ListOperationsRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.ListOperationsRequest.name', index=0,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='filter', full_name='google.longrunning.ListOperationsRequest.filter', index=1,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='page_size', full_name='google.longrunning.ListOperationsRequest.page_size', index=2,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='page_token', full_name='google.longrunning.ListOperationsRequest.page_token', index=3,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=378,
+  serialized_end=470,
+)
+
+
+_LISTOPERATIONSRESPONSE = _descriptor.Descriptor(
+  name='ListOperationsResponse',
+  full_name='google.longrunning.ListOperationsResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='operations', full_name='google.longrunning.ListOperationsResponse.operations', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='next_page_token', full_name='google.longrunning.ListOperationsResponse.next_page_token', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=472,
+  serialized_end=572,
+)
+
+
+_CANCELOPERATIONREQUEST = _descriptor.Descriptor(
+  name='CancelOperationRequest',
+  full_name='google.longrunning.CancelOperationRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.CancelOperationRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=574,
+  serialized_end=612,
+)
+
+
+_DELETEOPERATIONREQUEST = _descriptor.Descriptor(
+  name='DeleteOperationRequest',
+  full_name='google.longrunning.DeleteOperationRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.DeleteOperationRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=614,
+  serialized_end=652,
+)
+
+_OPERATION.fields_by_name['metadata'].message_type = google_dot_protobuf_dot_any__pb2._ANY
+_OPERATION.fields_by_name['error'].message_type = google_dot_rpc_dot_status__pb2._STATUS
+_OPERATION.fields_by_name['response'].message_type = google_dot_protobuf_dot_any__pb2._ANY
+_OPERATION.oneofs_by_name['result'].fields.append(
+  _OPERATION.fields_by_name['error'])
+_OPERATION.fields_by_name['error'].containing_oneof = _OPERATION.oneofs_by_name['result']
+_OPERATION.oneofs_by_name['result'].fields.append(
+  _OPERATION.fields_by_name['response'])
+_OPERATION.fields_by_name['response'].containing_oneof = _OPERATION.oneofs_by_name['result']
+_LISTOPERATIONSRESPONSE.fields_by_name['operations'].message_type = _OPERATION
+DESCRIPTOR.message_types_by_name['Operation'] = _OPERATION
+DESCRIPTOR.message_types_by_name['GetOperationRequest'] = _GETOPERATIONREQUEST
+DESCRIPTOR.message_types_by_name['ListOperationsRequest'] = _LISTOPERATIONSREQUEST
+DESCRIPTOR.message_types_by_name['ListOperationsResponse'] = _LISTOPERATIONSRESPONSE
+DESCRIPTOR.message_types_by_name['CancelOperationRequest'] = _CANCELOPERATIONREQUEST
+DESCRIPTOR.message_types_by_name['DeleteOperationRequest'] = _DELETEOPERATIONREQUEST
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Operation = _reflection.GeneratedProtocolMessageType('Operation', (_message.Message,), dict(
+  DESCRIPTOR = _OPERATION,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.Operation)
+  ))
+_sym_db.RegisterMessage(Operation)
+
+GetOperationRequest = _reflection.GeneratedProtocolMessageType('GetOperationRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETOPERATIONREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.GetOperationRequest)
+  ))
+_sym_db.RegisterMessage(GetOperationRequest)
+
+ListOperationsRequest = _reflection.GeneratedProtocolMessageType('ListOperationsRequest', (_message.Message,), dict(
+  DESCRIPTOR = _LISTOPERATIONSREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.ListOperationsRequest)
+  ))
+_sym_db.RegisterMessage(ListOperationsRequest)
+
+ListOperationsResponse = _reflection.GeneratedProtocolMessageType('ListOperationsResponse', (_message.Message,), dict(
+  DESCRIPTOR = _LISTOPERATIONSRESPONSE,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.ListOperationsResponse)
+  ))
+_sym_db.RegisterMessage(ListOperationsResponse)
+
+CancelOperationRequest = _reflection.GeneratedProtocolMessageType('CancelOperationRequest', (_message.Message,), dict(
+  DESCRIPTOR = _CANCELOPERATIONREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.CancelOperationRequest)
+  ))
+_sym_db.RegisterMessage(CancelOperationRequest)
+
+DeleteOperationRequest = _reflection.GeneratedProtocolMessageType('DeleteOperationRequest', (_message.Message,), dict(
+  DESCRIPTOR = _DELETEOPERATIONREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.DeleteOperationRequest)
+  ))
+_sym_db.RegisterMessage(DeleteOperationRequest)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\026com.google.longrunningB\017OperationsProtoP\001Z=google.golang.org/genproto/googleapis/longrunning;longrunning\252\002\022Google.LongRunning\312\002\022Google\\LongRunning'))
+
+_OPERATIONS = _descriptor.ServiceDescriptor(
+  name='Operations',
+  full_name='google.longrunning.Operations',
+  file=DESCRIPTOR,
+  index=0,
+  options=None,
+  serialized_start=655,
+  serialized_end=1179,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='ListOperations',
+    full_name='google.longrunning.Operations.ListOperations',
+    index=0,
+    containing_service=None,
+    input_type=_LISTOPERATIONSREQUEST,
+    output_type=_LISTOPERATIONSRESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002\027\022\025/v1/{name=operations}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='GetOperation',
+    full_name='google.longrunning.Operations.GetOperation',
+    index=1,
+    containing_service=None,
+    input_type=_GETOPERATIONREQUEST,
+    output_type=_OPERATION,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002\032\022\030/v1/{name=operations/**}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='DeleteOperation',
+    full_name='google.longrunning.Operations.DeleteOperation',
+    index=2,
+    containing_service=None,
+    input_type=_DELETEOPERATIONREQUEST,
+    output_type=google_dot_protobuf_dot_empty__pb2._EMPTY,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002\032*\030/v1/{name=operations/**}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='CancelOperation',
+    full_name='google.longrunning.Operations.CancelOperation',
+    index=3,
+    containing_service=None,
+    input_type=_CANCELOPERATIONREQUEST,
+    output_type=google_dot_protobuf_dot_empty__pb2._EMPTY,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002$\"\037/v1/{name=operations/**}:cancel:\001*')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_OPERATIONS)
+
+DESCRIPTOR.services_by_name['Operations'] = _OPERATIONS
+
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/google/longrunning/operations_pb2_grpc.py b/src/buildstream/_protos/google/longrunning/operations_pb2_grpc.py
new file mode 100644
index 000000000..8f89862e7
--- /dev/null
+++ b/src/buildstream/_protos/google/longrunning/operations_pb2_grpc.py
@@ -0,0 +1,132 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.google.longrunning import operations_pb2 as google_dot_longrunning_dot_operations__pb2
+from google.protobuf import empty_pb2 as google_dot_protobuf_dot_empty__pb2
+
+
+class OperationsStub(object):
+  """Manages long-running operations with an API service.
+
+  When an API method normally takes long time to complete, it can be designed
+  to return [Operation][google.longrunning.Operation] to the client, and the client can use this
+  interface to receive the real response asynchronously by polling the
+  operation resource, or pass the operation resource to another API (such as
+  Google Cloud Pub/Sub API) to receive the response.  Any API service that
+  returns long-running operations should implement the `Operations` interface
+  so developers can have a consistent client experience.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.ListOperations = channel.unary_unary(
+        '/google.longrunning.Operations/ListOperations',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.ListOperationsRequest.SerializeToString,
+        response_deserializer=google_dot_longrunning_dot_operations__pb2.ListOperationsResponse.FromString,
+        )
+    self.GetOperation = channel.unary_unary(
+        '/google.longrunning.Operations/GetOperation',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.GetOperationRequest.SerializeToString,
+        response_deserializer=google_dot_longrunning_dot_operations__pb2.Operation.FromString,
+        )
+    self.DeleteOperation = channel.unary_unary(
+        '/google.longrunning.Operations/DeleteOperation',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.DeleteOperationRequest.SerializeToString,
+        response_deserializer=google_dot_protobuf_dot_empty__pb2.Empty.FromString,
+        )
+    self.CancelOperation = channel.unary_unary(
+        '/google.longrunning.Operations/CancelOperation',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.CancelOperationRequest.SerializeToString,
+        response_deserializer=google_dot_protobuf_dot_empty__pb2.Empty.FromString,
+        )
+
+
+class OperationsServicer(object):
+  """Manages long-running operations with an API service.
+
+  When an API method normally takes long time to complete, it can be designed
+  to return [Operation][google.longrunning.Operation] to the client, and the client can use this
+  interface to receive the real response asynchronously by polling the
+  operation resource, or pass the operation resource to another API (such as
+  Google Cloud Pub/Sub API) to receive the response.  Any API service that
+  returns long-running operations should implement the `Operations` interface
+  so developers can have a consistent client experience.
+  """
+
+  def ListOperations(self, request, context):
+    """Lists operations that match the specified filter in the request. If the
+    server doesn't support this method, it returns `UNIMPLEMENTED`.
+
+    NOTE: the `name` binding below allows API services to override the binding
+    to use different resource name schemes, such as `users/*/operations`.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def GetOperation(self, request, context):
+    """Gets the latest state of a long-running operation.  Clients can use this
+    method to poll the operation result at intervals as recommended by the API
+    service.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def DeleteOperation(self, request, context):
+    """Deletes a long-running operation. This method indicates that the client is
+    no longer interested in the operation result. It does not cancel the
+    operation. If the server doesn't support this method, it returns
+    `google.rpc.Code.UNIMPLEMENTED`.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def CancelOperation(self, request, context):
+    """Starts asynchronous cancellation on a long-running operation.  The server
+    makes a best effort to cancel the operation, but success is not
+    guaranteed.  If the server doesn't support this method, it returns
+    `google.rpc.Code.UNIMPLEMENTED`.  Clients can use
+    [Operations.GetOperation][google.longrunning.Operations.GetOperation] or
+    other methods to check whether the cancellation succeeded or whether the
+    operation completed despite cancellation. On successful cancellation,
+    the operation is not deleted; instead, it becomes an operation with
+    an [Operation.error][google.longrunning.Operation.error] value with a [google.rpc.Status.code][google.rpc.Status.code] of 1,
+    corresponding to `Code.CANCELLED`.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_OperationsServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'ListOperations': grpc.unary_unary_rpc_method_handler(
+          servicer.ListOperations,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.ListOperationsRequest.FromString,
+          response_serializer=google_dot_longrunning_dot_operations__pb2.ListOperationsResponse.SerializeToString,
+      ),
+      'GetOperation': grpc.unary_unary_rpc_method_handler(
+          servicer.GetOperation,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.GetOperationRequest.FromString,
+          response_serializer=google_dot_longrunning_dot_operations__pb2.Operation.SerializeToString,
+      ),
+      'DeleteOperation': grpc.unary_unary_rpc_method_handler(
+          servicer.DeleteOperation,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.DeleteOperationRequest.FromString,
+          response_serializer=google_dot_protobuf_dot_empty__pb2.Empty.SerializeToString,
+      ),
+      'CancelOperation': grpc.unary_unary_rpc_method_handler(
+          servicer.CancelOperation,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.CancelOperationRequest.FromString,
+          response_serializer=google_dot_protobuf_dot_empty__pb2.Empty.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'google.longrunning.Operations', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/src/buildstream/_protos/google/rpc/__init__.py b/src/buildstream/_protos/google/rpc/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/__init__.py
diff --git a/src/buildstream/_protos/google/rpc/code.proto b/src/buildstream/_protos/google/rpc/code.proto
new file mode 100644
index 000000000..74e2c5c9a
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/code.proto
@@ -0,0 +1,186 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.rpc;
+
+option go_package = "google.golang.org/genproto/googleapis/rpc/code;code";
+option java_multiple_files = true;
+option java_outer_classname = "CodeProto";
+option java_package = "com.google.rpc";
+option objc_class_prefix = "RPC";
+
+
+// The canonical error codes for Google APIs.
+//
+//
+// Sometimes multiple error codes may apply.  Services should return
+// the most specific error code that applies.  For example, prefer
+// `OUT_OF_RANGE` over `FAILED_PRECONDITION` if both codes apply.
+// Similarly prefer `NOT_FOUND` or `ALREADY_EXISTS` over `FAILED_PRECONDITION`.
+enum Code {
+  // Not an error; returned on success
+  //
+  // HTTP Mapping: 200 OK
+  OK = 0;
+
+  // The operation was cancelled, typically by the caller.
+  //
+  // HTTP Mapping: 499 Client Closed Request
+  CANCELLED = 1;
+
+  // Unknown error.  For example, this error may be returned when
+  // a `Status` value received from another address space belongs to
+  // an error space that is not known in this address space.  Also
+  // errors raised by APIs that do not return enough error information
+  // may be converted to this error.
+  //
+  // HTTP Mapping: 500 Internal Server Error
+  UNKNOWN = 2;
+
+  // The client specified an invalid argument.  Note that this differs
+  // from `FAILED_PRECONDITION`.  `INVALID_ARGUMENT` indicates arguments
+  // that are problematic regardless of the state of the system
+  // (e.g., a malformed file name).
+  //
+  // HTTP Mapping: 400 Bad Request
+  INVALID_ARGUMENT = 3;
+
+  // The deadline expired before the operation could complete. For operations
+  // that change the state of the system, this error may be returned
+  // even if the operation has completed successfully.  For example, a
+  // successful response from a server could have been delayed long
+  // enough for the deadline to expire.
+  //
+  // HTTP Mapping: 504 Gateway Timeout
+  DEADLINE_EXCEEDED = 4;
+
+  // Some requested entity (e.g., file or directory) was not found.
+  //
+  // Note to server developers: if a request is denied for an entire class
+  // of users, such as gradual feature rollout or undocumented whitelist,
+  // `NOT_FOUND` may be used. If a request is denied for some users within
+  // a class of users, such as user-based access control, `PERMISSION_DENIED`
+  // must be used.
+  //
+  // HTTP Mapping: 404 Not Found
+  NOT_FOUND = 5;
+
+  // The entity that a client attempted to create (e.g., file or directory)
+  // already exists.
+  //
+  // HTTP Mapping: 409 Conflict
+  ALREADY_EXISTS = 6;
+
+  // The caller does not have permission to execute the specified
+  // operation. `PERMISSION_DENIED` must not be used for rejections
+  // caused by exhausting some resource (use `RESOURCE_EXHAUSTED`
+  // instead for those errors). `PERMISSION_DENIED` must not be
+  // used if the caller can not be identified (use `UNAUTHENTICATED`
+  // instead for those errors). This error code does not imply the
+  // request is valid or the requested entity exists or satisfies
+  // other pre-conditions.
+  //
+  // HTTP Mapping: 403 Forbidden
+  PERMISSION_DENIED = 7;
+
+  // The request does not have valid authentication credentials for the
+  // operation.
+  //
+  // HTTP Mapping: 401 Unauthorized
+  UNAUTHENTICATED = 16;
+
+  // Some resource has been exhausted, perhaps a per-user quota, or
+  // perhaps the entire file system is out of space.
+  //
+  // HTTP Mapping: 429 Too Many Requests
+  RESOURCE_EXHAUSTED = 8;
+
+  // The operation was rejected because the system is not in a state
+  // required for the operation's execution.  For example, the directory
+  // to be deleted is non-empty, an rmdir operation is applied to
+  // a non-directory, etc.
+  //
+  // Service implementors can use the following guidelines to decide
+  // between `FAILED_PRECONDITION`, `ABORTED`, and `UNAVAILABLE`:
+  //  (a) Use `UNAVAILABLE` if the client can retry just the failing call.
+  //  (b) Use `ABORTED` if the client should retry at a higher level
+  //      (e.g., when a client-specified test-and-set fails, indicating the
+  //      client should restart a read-modify-write sequence).
+  //  (c) Use `FAILED_PRECONDITION` if the client should not retry until
+  //      the system state has been explicitly fixed.  E.g., if an "rmdir"
+  //      fails because the directory is non-empty, `FAILED_PRECONDITION`
+  //      should be returned since the client should not retry unless
+  //      the files are deleted from the directory.
+  //
+  // HTTP Mapping: 400 Bad Request
+  FAILED_PRECONDITION = 9;
+
+  // The operation was aborted, typically due to a concurrency issue such as
+  // a sequencer check failure or transaction abort.
+  //
+  // See the guidelines above for deciding between `FAILED_PRECONDITION`,
+  // `ABORTED`, and `UNAVAILABLE`.
+  //
+  // HTTP Mapping: 409 Conflict
+  ABORTED = 10;
+
+  // The operation was attempted past the valid range.  E.g., seeking or
+  // reading past end-of-file.
+  //
+  // Unlike `INVALID_ARGUMENT`, this error indicates a problem that may
+  // be fixed if the system state changes. For example, a 32-bit file
+  // system will generate `INVALID_ARGUMENT` if asked to read at an
+  // offset that is not in the range [0,2^32-1], but it will generate
+  // `OUT_OF_RANGE` if asked to read from an offset past the current
+  // file size.
+  //
+  // There is a fair bit of overlap between `FAILED_PRECONDITION` and
+  // `OUT_OF_RANGE`.  We recommend using `OUT_OF_RANGE` (the more specific
+  // error) when it applies so that callers who are iterating through
+  // a space can easily look for an `OUT_OF_RANGE` error to detect when
+  // they are done.
+  //
+  // HTTP Mapping: 400 Bad Request
+  OUT_OF_RANGE = 11;
+
+  // The operation is not implemented or is not supported/enabled in this
+  // service.
+  //
+  // HTTP Mapping: 501 Not Implemented
+  UNIMPLEMENTED = 12;
+
+  // Internal errors.  This means that some invariants expected by the
+  // underlying system have been broken.  This error code is reserved
+  // for serious errors.
+  //
+  // HTTP Mapping: 500 Internal Server Error
+  INTERNAL = 13;
+
+  // The service is currently unavailable.  This is most likely a
+  // transient condition, which can be corrected by retrying with
+  // a backoff.
+  //
+  // See the guidelines above for deciding between `FAILED_PRECONDITION`,
+  // `ABORTED`, and `UNAVAILABLE`.
+  //
+  // HTTP Mapping: 503 Service Unavailable
+  UNAVAILABLE = 14;
+
+  // Unrecoverable data loss or corruption.
+  //
+  // HTTP Mapping: 500 Internal Server Error
+  DATA_LOSS = 15;
+}
\ No newline at end of file
diff --git a/src/buildstream/_protos/google/rpc/code_pb2.py b/src/buildstream/_protos/google/rpc/code_pb2.py
new file mode 100644
index 000000000..e06dea194
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/code_pb2.py
@@ -0,0 +1,133 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/rpc/code.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf.internal import enum_type_wrapper
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/rpc/code.proto',
+  package='google.rpc',
+  syntax='proto3',
+  serialized_options=_b('\n\016com.google.rpcB\tCodeProtoP\001Z3google.golang.org/genproto/googleapis/rpc/code;code\242\002\003RPC'),
+  serialized_pb=_b('\n\x15google/rpc/code.proto\x12\ngoogle.rpc*\xb7\x02\n\x04\x43ode\x12\x06\n\x02OK\x10\x00\x12\r\n\tCANCELLED\x10\x01\x12\x0b\n\x07UNKNOWN\x10\x02\x12\x14\n\x10INVALID_ARGUMENT\x10\x03\x12\x15\n\x11\x44\x45\x41\x44LINE_EXCEEDED\x10\x04\x12\r\n\tNOT_FOUND\x10\x05\x12\x12\n\x0e\x41LREADY_EXISTS\x10\x06\x12\x15\n\x11PERMISSION_DENIED\x10\x07\x12\x13\n\x0fUNAUTHENTICATED\x10\x10\x12\x16\n\x12RESOURCE_EXHAUSTED\x10\x08\x12\x17\n\x13\x46\x41ILED_PRECONDITION\x10\t\x12\x0b\n\x07\x41\x42ORTED\x10\n\x12\x10\n\x0cOUT_OF_RANGE\x10\x0b\x12\x11\n\rUNIMPLEMENTED\x10\x0c\x12\x0c\n\x08INTERNAL\x10\r\x12\x0f\n\x0bUNAVAILABLE\x10\x0e\x12\r\n\tDATA_LOSS\x10\x0f\x42X\n\x0e\x63om.google.rpcB\tCodeProtoP\x01Z3google.golang.org/genproto/googleapis/rpc/code;code\xa2\x02\x03RPCb\x06proto3')
+)
+
+_CODE = _descriptor.EnumDescriptor(
+  name='Code',
+  full_name='google.rpc.Code',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='OK', index=0, number=0,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='CANCELLED', index=1, number=1,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='UNKNOWN', index=2, number=2,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='INVALID_ARGUMENT', index=3, number=3,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='DEADLINE_EXCEEDED', index=4, number=4,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='NOT_FOUND', index=5, number=5,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='ALREADY_EXISTS', index=6, number=6,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='PERMISSION_DENIED', index=7, number=7,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='UNAUTHENTICATED', index=8, number=16,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='RESOURCE_EXHAUSTED', index=9, number=8,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='FAILED_PRECONDITION', index=10, number=9,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='ABORTED', index=11, number=10,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='OUT_OF_RANGE', index=12, number=11,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='UNIMPLEMENTED', index=13, number=12,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='INTERNAL', index=14, number=13,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='UNAVAILABLE', index=15, number=14,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='DATA_LOSS', index=16, number=15,
+      serialized_options=None,
+      type=None),
+  ],
+  containing_type=None,
+  serialized_options=None,
+  serialized_start=38,
+  serialized_end=349,
+)
+_sym_db.RegisterEnumDescriptor(_CODE)
+
+Code = enum_type_wrapper.EnumTypeWrapper(_CODE)
+OK = 0
+CANCELLED = 1
+UNKNOWN = 2
+INVALID_ARGUMENT = 3
+DEADLINE_EXCEEDED = 4
+NOT_FOUND = 5
+ALREADY_EXISTS = 6
+PERMISSION_DENIED = 7
+UNAUTHENTICATED = 16
+RESOURCE_EXHAUSTED = 8
+FAILED_PRECONDITION = 9
+ABORTED = 10
+OUT_OF_RANGE = 11
+UNIMPLEMENTED = 12
+INTERNAL = 13
+UNAVAILABLE = 14
+DATA_LOSS = 15
+
+
+DESCRIPTOR.enum_types_by_name['Code'] = _CODE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+
+DESCRIPTOR._options = None
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/google/rpc/code_pb2_grpc.py b/src/buildstream/_protos/google/rpc/code_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/code_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
diff --git a/src/buildstream/_protos/google/rpc/status.proto b/src/buildstream/_protos/google/rpc/status.proto
new file mode 100644
index 000000000..0839ee966
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/status.proto
@@ -0,0 +1,92 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.rpc;
+
+import "google/protobuf/any.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/rpc/status;status";
+option java_multiple_files = true;
+option java_outer_classname = "StatusProto";
+option java_package = "com.google.rpc";
+option objc_class_prefix = "RPC";
+
+
+// The `Status` type defines a logical error model that is suitable for different
+// programming environments, including REST APIs and RPC APIs. It is used by
+// [gRPC](https://github.com/grpc). The error model is designed to be:
+//
+// - Simple to use and understand for most users
+// - Flexible enough to meet unexpected needs
+//
+// # Overview
+//
+// The `Status` message contains three pieces of data: error code, error message,
+// and error details. The error code should be an enum value of
+// [google.rpc.Code][google.rpc.Code], but it may accept additional error codes if needed.  The
+// error message should be a developer-facing English message that helps
+// developers *understand* and *resolve* the error. If a localized user-facing
+// error message is needed, put the localized message in the error details or
+// localize it in the client. The optional error details may contain arbitrary
+// information about the error. There is a predefined set of error detail types
+// in the package `google.rpc` that can be used for common error conditions.
+//
+// # Language mapping
+//
+// The `Status` message is the logical representation of the error model, but it
+// is not necessarily the actual wire format. When the `Status` message is
+// exposed in different client libraries and different wire protocols, it can be
+// mapped differently. For example, it will likely be mapped to some exceptions
+// in Java, but more likely mapped to some error codes in C.
+//
+// # Other uses
+//
+// The error model and the `Status` message can be used in a variety of
+// environments, either with or without APIs, to provide a
+// consistent developer experience across different environments.
+//
+// Example uses of this error model include:
+//
+// - Partial errors. If a service needs to return partial errors to the client,
+//     it may embed the `Status` in the normal response to indicate the partial
+//     errors.
+//
+// - Workflow errors. A typical workflow has multiple steps. Each step may
+//     have a `Status` message for error reporting.
+//
+// - Batch operations. If a client uses batch request and batch response, the
+//     `Status` message should be used directly inside batch response, one for
+//     each error sub-response.
+//
+// - Asynchronous operations. If an API call embeds asynchronous operation
+//     results in its response, the status of those operations should be
+//     represented directly using the `Status` message.
+//
+// - Logging. If some API errors are stored in logs, the message `Status` could
+//     be used directly after any stripping needed for security/privacy reasons.
+message Status {
+  // The status code, which should be an enum value of [google.rpc.Code][google.rpc.Code].
+  int32 code = 1;
+
+  // A developer-facing error message, which should be in English. Any
+  // user-facing error message should be localized and sent in the
+  // [google.rpc.Status.details][google.rpc.Status.details] field, or localized by the client.
+  string message = 2;
+
+  // A list of messages that carry the error details.  There is a common set of
+  // message types for APIs to use.
+  repeated google.protobuf.Any details = 3;
+}
diff --git a/src/buildstream/_protos/google/rpc/status_pb2.py b/src/buildstream/_protos/google/rpc/status_pb2.py
new file mode 100644
index 000000000..6c4772311
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/status_pb2.py
@@ -0,0 +1,88 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/rpc/status.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from google.protobuf import any_pb2 as google_dot_protobuf_dot_any__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/rpc/status.proto',
+  package='google.rpc',
+  syntax='proto3',
+  serialized_pb=_b('\n\x17google/rpc/status.proto\x12\ngoogle.rpc\x1a\x19google/protobuf/any.proto\"N\n\x06Status\x12\x0c\n\x04\x63ode\x18\x01 \x01(\x05\x12\x0f\n\x07message\x18\x02 \x01(\t\x12%\n\x07\x64\x65tails\x18\x03 \x03(\x0b\x32\x14.google.protobuf.AnyB^\n\x0e\x63om.google.rpcB\x0bStatusProtoP\x01Z7google.golang.org/genproto/googleapis/rpc/status;status\xa2\x02\x03RPCb\x06proto3')
+  ,
+  dependencies=[google_dot_protobuf_dot_any__pb2.DESCRIPTOR,])
+
+
+
+
+_STATUS = _descriptor.Descriptor(
+  name='Status',
+  full_name='google.rpc.Status',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='code', full_name='google.rpc.Status.code', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='message', full_name='google.rpc.Status.message', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='details', full_name='google.rpc.Status.details', index=2,
+      number=3, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=66,
+  serialized_end=144,
+)
+
+_STATUS.fields_by_name['details'].message_type = google_dot_protobuf_dot_any__pb2._ANY
+DESCRIPTOR.message_types_by_name['Status'] = _STATUS
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Status = _reflection.GeneratedProtocolMessageType('Status', (_message.Message,), dict(
+  DESCRIPTOR = _STATUS,
+  __module__ = 'google.rpc.status_pb2'
+  # @@protoc_insertion_point(class_scope:google.rpc.Status)
+  ))
+_sym_db.RegisterMessage(Status)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\016com.google.rpcB\013StatusProtoP\001Z7google.golang.org/genproto/googleapis/rpc/status;status\242\002\003RPC'))
+# @@protoc_insertion_point(module_scope)
diff --git a/src/buildstream/_protos/google/rpc/status_pb2_grpc.py b/src/buildstream/_protos/google/rpc/status_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/src/buildstream/_protos/google/rpc/status_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+