SERVER-58506 Expose Server-Parameter Settability

5 files changed, 210 insertions, 8 deletions

diff --git a/etc/backports_required_for_multiversion_tests.yml b/etc/backports_required_for_multiversion_tests.yml
index a6ab07267b6..da2cbbb6aa2 100644
--- a/etc/backports_required_for_multiversion_tests.yml
+++ b/etc/backports_required_for_multiversion_tests.yml
@@ -124,6 +124,8 @@ last-continuous:
       test_file: jstests/sharding/coordinate_txn_commit_with_tickets_exhausted.js
     - ticket: SERVER-60685
       test_file: jstests/sharding/cancel_coordinate_txn_commit_with_tickets_exhausted.js
+    - ticket: SERVER-58506
+      test_file: jstests/noPassthrough/getParameterWithDetails.js
     - ticket: SERVER-57766
       test_file: jstests/sharding/resharding_metrics.js
     - ticket: SERVER-61757
@@ -411,6 +413,8 @@ last-lts:
       test_file: jstests/sharding/coordinate_txn_commit_with_tickets_exhausted.js
     - ticket: SERVER-60685
       test_file: jstests/sharding/cancel_coordinate_txn_commit_with_tickets_exhausted.js
+    - ticket: SERVER-58506
+      test_file: jstests/noPassthrough/getParameterWithDetails.js
     - ticket: SERVER-57766
       test_file: jstests/sharding/resharding_metrics.js
     - ticket: SERVER-61757
diff --git a/jstests/noPassthrough/getParameterWithDetails.js b/jstests/noPassthrough/getParameterWithDetails.js
new file mode 100644
index 00000000000..519970e9030
--- /dev/null
+++ b/jstests/noPassthrough/getParameterWithDetails.js
@@ -0,0 +1,119 @@
+// Test getParameter on mongod and mongos, including the with-detail syntax.
+//
+// @tags: [requires_replication, requires_sharding]
+
+(() => {
+    'use strict';
+    const st = new ShardingTest({shards: 1, mongos: 1});
+    const mongosDB = st.s0.getDB("admin");
+    const shardDB = st.shard0.getDB("admin");
+
+    function checkSpecificParameters(dbConn, parameters) {
+        const plainCommand = {getParameter: 1};
+        const detailCommand = {getParameter: {showDetails: true}};
+
+        // Append requests to retrieve specific parameters.
+        parameters.forEach((parameter) => {
+            plainCommand[parameter["name"]] = 1;
+            detailCommand[parameter["name"]] = 1;
+        });
+
+        // Fetch results
+        const resultsPlain = assert.commandWorked(dbConn.adminCommand(plainCommand));
+        const resultsWithDetail = assert.commandWorked(dbConn.adminCommand(detailCommand));
+
+        // Ensure requested parameters had expected values and detail information.
+        parameters.forEach((parameter) => {
+            const expectedDetailedResultObj = parameter["result"];
+            const expectedValue = expectedDetailedResultObj["value"];
+            const plainErrMsg = "Expecting plain result to contain: " + tojson(parameter) +
+                "but found: " + tojson(resultsPlain);
+            const detailErrMsg = "Expecting detail result to contain: " + tojson(parameter) +
+                "but found: " + tojson(resultsWithDetail);
+
+            assert.eq(resultsPlain[parameter["name"]], expectedValue, plainErrMsg);
+            assert.docEq(
+                resultsWithDetail[parameter["name"]], expectedDetailedResultObj, detailErrMsg);
+        });
+    }
+
+    function checkAllParameters(dbConn) {
+        const plainCommand = {getParameter: '*'};
+        const detailCommand = {getParameter: {showDetails: true, allParameters: true}};
+
+        // Fetch results
+        let resultsPlain = assert.commandWorked(dbConn.adminCommand(plainCommand));
+        let resultsWithDetail = assert.commandWorked(dbConn.adminCommand(detailCommand));
+
+        // Ensure results are consistent between syntaxes. We don't check for explicit expected
+        // values here to avoid the need to specify them for every parameter and update this file
+        // every time one is added or changes in value.
+        Object.keys(resultsWithDetail).forEach((k) => {
+            if (resultsWithDetail[k].hasOwnProperty("value")) {
+                assert.eq(resultsWithDetail[k]["value"],
+                          resultsPlain[k],
+                          "In all parameters, mismatch for parameter " + k + ":" +
+                              tojson(resultsWithDetail[k]) + " vs " + tojson(resultsPlain[k]));
+            }
+        });
+        Object.keys(resultsPlain).forEach((k) => {
+            assert(resultsWithDetail.hasOwnProperty(k));
+            if (resultsWithDetail[k].hasOwnProperty("value")) {
+                assert.eq(resultsPlain[k], resultsWithDetail[k]["value"]);
+            }
+        });
+    }
+
+    // Each of the entries in the following array is an object with two keys, "name" and "result".
+    // "name" is the name of a server parameter, and "result" is the expected object
+    // getParameter should return for that parameter, when details are requested.
+    const specificParametersBothProcesses = [
+        {
+            name: "ShardingTaskExecutorPoolMinSize",
+            result: {value: 1, settableAtRuntime: true, settableAtStartup: true}
+        },
+        {
+            name: "maxLogSizeKB",
+            result: {value: 10, settableAtRuntime: true, settableAtStartup: true}
+        },
+        {
+            name: "cursorTimeoutMillis",
+            result: {value: NumberLong(600000), settableAtRuntime: true, settableAtStartup: true}
+        }
+    ];
+    const specificParametersMongodOnly = [
+        {
+            name: "ttlMonitorEnabled",
+            result: {value: true, settableAtRuntime: true, settableAtStartup: true}
+        },
+        {
+            name: "wiredTigerMaxCacheOverflowSizeGB",
+            result: {value: 0, settableAtRuntime: true, settableAtStartup: false}
+        },
+        {
+            name: "shardedIndexConsistencyCheckIntervalMS",
+            result: {value: 600000, settableAtRuntime: false, settableAtStartup: true}
+        },
+    ];
+    const specificParametersMongosOnly = [
+        {
+            name: "taskExecutorPoolSize",
+            result: {value: 1, settableAtRuntime: true, settableAtStartup: true}
+        },
+        {
+            name: "userCacheInvalidationIntervalSecs",
+            result: {value: 30, settableAtRuntime: true, settableAtStartup: true}
+        },
+    ];
+
+    checkSpecificParameters(mongosDB, specificParametersBothProcesses);
+    checkSpecificParameters(shardDB, specificParametersBothProcesses);
+
+    checkSpecificParameters(shardDB, specificParametersMongodOnly);
+    checkSpecificParameters(mongosDB, specificParametersMongosOnly);
+
+    checkAllParameters(mongosDB);
+    checkAllParameters(shardDB);
+
+    st.stop();
+})();
diff --git a/src/mongo/db/commands/parameters.cpp b/src/mongo/db/commands/parameters.cpp
index b08a9ec2003..ea32db50df2 100644
--- a/src/mongo/db/commands/parameters.cpp
+++ b/src/mongo/db/commands/parameters.cpp
@@ -33,6 +33,7 @@
 
 #include <set>
 
+#include "mongo/bson/bsontypes.h"
 #include "mongo/bson/json.h"
 #include "mongo/bson/mutable/document.h"
 #include "mongo/client/replica_set_monitor.h"
@@ -44,6 +45,7 @@
 #include "mongo/db/storage/kv/kv_engine.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/idl/command_generic_argument.h"
+#include "mongo/idl/server_parameter_gen.h"
 #include "mongo/logv2/log.h"
 #include "mongo/util/str.h"
 
@@ -186,6 +188,19 @@ Status setLogComponentVerbosity(const BSONObj& bsonSettings) {
     return Status::OK();
 }
 
+
+GetParameterOptions parseGetParameterOptions(BSONElement elem) {
+    if (elem.type() == BSONType::Object) {
+        return GetParameterOptions::parse({"getParameter"}, elem.Obj());
+    }
+    if ((elem.type() == BSONType::String) && (elem.valueStringDataSafe() == "*"_sd)) {
+        GetParameterOptions ret;
+        ret.setAllParameters(true);
+        return ret;
+    }
+    return GetParameterOptions{};
+}
+
 // for automationServiceDescription
 Mutex autoServiceDescriptorMutex;
 std::string autoServiceDescriptorValue;
@@ -213,26 +228,39 @@ public:
     std::string help() const override {
         std::string h =
             "get administrative option(s)\nexample:\n"
-            "{ getParameter:1, notablescan:1 }\n";
+            "{ getParameter:1, notablescan:1 }\n"
+            "pass a document as the value for getParameter to request options\nexample:\n"
+            "{ getParameter:{showDetails: true}, notablescan:1}\n";
         appendParameterNames(&h);
-        h += "{ getParameter:'*' } to get everything\n";
+        h += "{ getParameter:'*' } or { getParameter:{allParameters: true} } to get everything\n";
         return h;
     }
     bool errmsgRun(OperationContext* opCtx,
                    const string& dbname,
                    const BSONObj& cmdObj,
                    string& errmsg,
-                   BSONObjBuilder& result) {
-        bool all = cmdObj.firstElement().str() == "*";
+                   BSONObjBuilder& result) override {
+        const auto options = parseGetParameterOptions(cmdObj.firstElement());
+        const bool all = options.getAllParameters();
 
         int before = result.len();
 
-        for (const auto& param : ServerParameterSet::getNodeParameterSet()->getMap()) {
-            if (all || cmdObj.hasElement(param.first.c_str())) {
-                param.second->append(opCtx, result, param.second->name());
+        const ServerParameter::Map& m = ServerParameterSet::getNodeParameterSet()->getMap();
+        for (ServerParameter::Map::const_iterator i = m.begin(); i != m.end(); ++i) {
+            if (all || cmdObj.hasElement(i->first.c_str())) {
+                if (options.getShowDetails()) {
+                    BSONObjBuilder detailBob(result.subobjStart(i->second->name()));
+                    i->second->append(opCtx, detailBob, "value");
+                    detailBob.appendBool("settableAtRuntime",
+                                         i->second->allowedToChangeAtRuntime());
+                    detailBob.appendBool("settableAtStartup",
+                                         i->second->allowedToChangeAtStartup());
+                    detailBob.doneFast();
+                } else {
+                    i->second->append(opCtx, result, i->second->name());
+                }
             }
         }
-
         if (before == result.len()) {
             errmsg = "no option found to get";
             return false;
diff --git a/src/mongo/idl/SConscript b/src/mongo/idl/SConscript
index 32815fc5a26..9f05ee0f7f0 100644
--- a/src/mongo/idl/SConscript
+++ b/src/mongo/idl/SConscript
@@ -37,10 +37,12 @@ env.Library(
     target='server_parameter',
     source=[
         'server_parameter.cpp',
+        'server_parameter.idl',
         'server_parameter_with_storage.cpp',
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
+        'idl_parser',
     ],
     LIBDEPS_PRIVATE=[
         '$BUILD_DIR/mongo/util/options_parser/options_parser',
diff --git a/src/mongo/idl/server_parameter.idl b/src/mongo/idl/server_parameter.idl
new file mode 100644
index 00000000000..2fb39ad0815
--- /dev/null
+++ b/src/mongo/idl/server_parameter.idl
@@ -0,0 +1,49 @@
+# Copyright (C) 2022-present MongoDB, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the Server Side Public License, version 1,
+# as published by MongoDB, Inc.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# Server Side Public License for more details.
+#
+# You should have received a copy of the Server Side Public License
+# along with this program. If not, see
+# <http://www.mongodb.com/licensing/server-side-public-license>.
+#
+# As a special exception, the copyright holders give permission to link the
+# code of portions of this program with the OpenSSL library under certain
+# conditions as described in each individual source file and distribute
+# linked combinations including the program with the OpenSSL library. You
+# must comply with the Server Side Public License in all respects for
+# all of the code used other than as permitted herein. If you modify file(s)
+# with this exception, you may extend this exception to your version of the
+# file(s), but you are not obligated to do so. If you do not wish to do so,
+# delete this exception statement from your version. If you delete this
+# exception statement from all source files in the program, then also delete
+# it in the license file.
+#
+# IDL constructs useful for all server parameters.
+
+global:
+    cpp_namespace: "mongo"
+
+imports:
+    - "mongo/idl/basic_types.idl"
+
+# Options for the getParameter command. Describes the object "options" when the command is run as 
+# {getParameter: <options>}
+structs:
+  GetParameterOptions:
+    description: 'Optional flags to pass to {getParameter: options, ...}'
+    fields: 
+      showDetails:
+        description: 'Return metadata about the server parameter along with its current value'
+        type: safeBool
+        default: false
+      allParameters:
+        description: 'Return all server parameters, not just the ones specified'
+        type: safeBool
+        default: false