Add pipeline lists to GraphQL

This adds Keyset pagination to GraphQL lists. PoC for that is
pipelines on merge requests and projects.

When paginating a list, the base-64 encoded id of the ordering
field (in most cases the primary key) can be passed in the `before` or
`after` GraphQL argument.

9 files changed, 115 insertions, 0 deletions

diff --git a/app/graphql/gitlab_schema.rb b/app/graphql/gitlab_schema.rb
index de4fc1d8e32..d9f9129d08a 100644
--- a/app/graphql/gitlab_schema.rb
+++ b/app/graphql/gitlab_schema.rb
@@ -2,7 +2,10 @@ class GitlabSchema < GraphQL::Schema
   use BatchLoader::GraphQL
   use Gitlab::Graphql::Authorize
   use Gitlab::Graphql::Present
+  use Gitlab::Graphql::Connections
 
   query(Types::QueryType)
+
+  default_max_page_size 100
   # mutation(Types::MutationType)
 end
diff --git a/app/graphql/resolvers/concerns/resolves_pipelines.rb b/app/graphql/resolvers/concerns/resolves_pipelines.rb
new file mode 100644
index 00000000000..9ec45378d8e
--- /dev/null
+++ b/app/graphql/resolvers/concerns/resolves_pipelines.rb
@@ -0,0 +1,23 @@
+module ResolvesPipelines
+  extend ActiveSupport::Concern
+
+  included do
+    type [Types::Ci::PipelineType], null: false
+    argument :status,
+             Types::Ci::PipelineStatusEnum,
+             required: false,
+             description: "Filter pipelines by their status"
+    argument :ref,
+             GraphQL::STRING_TYPE,
+             required: false,
+             description: "Filter pipelines by the ref they are run for"
+    argument :sha,
+             GraphQL::STRING_TYPE,
+             required: false,
+             description: "Filter pipelines by the sha of the commit they are run for"
+  end
+
+  def resolve_pipelines(project, params = {})
+    PipelinesFinder.new(project, context[:current_user], params).execute
+  end
+end
diff --git a/app/graphql/resolvers/merge_request_pipelines_resolver.rb b/app/graphql/resolvers/merge_request_pipelines_resolver.rb
new file mode 100644
index 00000000000..00b51ee1381
--- /dev/null
+++ b/app/graphql/resolvers/merge_request_pipelines_resolver.rb
@@ -0,0 +1,16 @@
+module Resolvers
+  class MergeRequestPipelinesResolver < BaseResolver
+    include ::ResolvesPipelines
+
+    alias_method :merge_request, :object
+
+    def resolve(**args)
+      resolve_pipelines(project, args)
+        .merge(merge_request.all_pipelines)
+    end
+
+    def project
+      merge_request.source_project
+    end
+  end
+end
diff --git a/app/graphql/resolvers/project_pipelines_resolver.rb b/app/graphql/resolvers/project_pipelines_resolver.rb
new file mode 100644
index 00000000000..7f175a3b26c
--- /dev/null
+++ b/app/graphql/resolvers/project_pipelines_resolver.rb
@@ -0,0 +1,11 @@
+module Resolvers
+  class ProjectPipelinesResolver < BaseResolver
+    include ResolvesPipelines
+
+    alias_method :project, :object
+
+    def resolve(**args)
+      resolve_pipelines(project, args)
+    end
+  end
+end
diff --git a/app/graphql/types/ci/pipeline_status_enum.rb b/app/graphql/types/ci/pipeline_status_enum.rb
new file mode 100644
index 00000000000..2c12e5001d8
--- /dev/null
+++ b/app/graphql/types/ci/pipeline_status_enum.rb
@@ -0,0 +1,9 @@
+module Types
+  module Ci
+    class PipelineStatusEnum < BaseEnum
+      ::Ci::Pipeline.all_state_names.each do |state_symbol|
+        value state_symbol.to_s.upcase, value: state_symbol.to_s
+      end
+    end
+  end
+end
diff --git a/app/graphql/types/ci/pipeline_type.rb b/app/graphql/types/ci/pipeline_type.rb
new file mode 100644
index 00000000000..bbb7d9354d0
--- /dev/null
+++ b/app/graphql/types/ci/pipeline_type.rb
@@ -0,0 +1,31 @@
+module Types
+  module Ci
+    class PipelineType < BaseObject
+      expose_permissions Types::PermissionTypes::Ci::Pipeline
+
+      graphql_name 'Pipeline'
+
+      field :id, GraphQL::ID_TYPE, null: false
+      field :iid, GraphQL::ID_TYPE, null: false
+
+      field :sha, GraphQL::STRING_TYPE, null: false
+      field :before_sha, GraphQL::STRING_TYPE, null: true
+      field :status, PipelineStatusEnum, null: false
+      field :duration,
+            GraphQL::INT_TYPE,
+            null: true,
+            description: "Duration of the pipeline in seconds"
+      field :coverage,
+            GraphQL::FLOAT_TYPE,
+            null: true,
+            description: "Coverage percentage"
+      field :created_at, Types::TimeType, null: false
+      field :updated_at, Types::TimeType, null: false
+      field :started_at, Types::TimeType, null: true
+      field :finished_at, Types::TimeType, null: true
+      field :committed_at, Types::TimeType, null: true
+
+      # TODO: Add triggering user as a type
+    end
+  end
+end
diff --git a/app/graphql/types/merge_request_type.rb b/app/graphql/types/merge_request_type.rb
index a1f3c0dd8c0..88cd2adc6dc 100644
--- a/app/graphql/types/merge_request_type.rb
+++ b/app/graphql/types/merge_request_type.rb
@@ -45,5 +45,11 @@ module Types
     field :upvotes, GraphQL::INT_TYPE, null: false
     field :downvotes, GraphQL::INT_TYPE, null: false
     field :subscribed, GraphQL::BOOLEAN_TYPE, method: :subscribed?, null: false
+
+    field :head_pipeline, Types::Ci::PipelineType, null: true, method: :actual_head_pipeline do
+      authorize :read_pipeline
+    end
+    field :pipelines, Types::Ci::PipelineType.connection_type,
+          resolver: Resolvers::MergeRequestPipelinesResolver
   end
 end
diff --git a/app/graphql/types/permission_types/ci/pipeline.rb b/app/graphql/types/permission_types/ci/pipeline.rb
new file mode 100644
index 00000000000..942539c7cf7
--- /dev/null
+++ b/app/graphql/types/permission_types/ci/pipeline.rb
@@ -0,0 +1,11 @@
+module Types
+  module PermissionTypes
+    module Ci
+      class Pipeline < BasePermissionType
+        graphql_name 'PipelinePermissions'
+
+        abilities :update_pipeline, :admin_pipeline, :destroy_pipeline
+      end
+    end
+  end
+end
diff --git a/app/graphql/types/project_type.rb b/app/graphql/types/project_type.rb
index a832e8b4bde..97707215b4e 100644
--- a/app/graphql/types/project_type.rb
+++ b/app/graphql/types/project_type.rb
@@ -70,5 +70,10 @@ module Types
           resolver: Resolvers::MergeRequestResolver do
       authorize :read_merge_request
     end
+
+    field :pipelines,
+          Types::Ci::PipelineType.connection_type,
+          null: false,
+          resolver: Resolvers::ProjectPipelinesResolver
   end
 end