SERVER-68576 Added number of sharded collections to serverStatus command.

5 files changed, 32 insertions, 4 deletions

diff --git a/jstests/sharding/resharding_abort_command.js b/jstests/sharding/resharding_abort_command.js
index f8e7aeaf9f5..7c5f4a95cb0 100644
--- a/jstests/sharding/resharding_abort_command.js
+++ b/jstests/sharding/resharding_abort_command.js
@@ -177,7 +177,7 @@ const runAbortWithFailpoint = (failpointName, failpointNodeType, abortLocation,
     // Resharding has not been attempted yet, so resharding metrics will not be reported. This means
     // shardingStatistics will be empty, and thus not reported. So we assert that the serverStatus
     // does not have shardingStatistics yet.
-    assert(!status.hasOwnProperty('shardingStatistics'), status);
+    assert(!status.shardingStatistics.hasOwnProperty("resharding"), status);
 
     let expectedAbortErrorCodes = ErrorCodes.OK;
     let expectedReshardingErrorCode = ErrorCodes.ReshardCollectionAborted;
diff --git a/jstests/sharding/resharding_feature_flagging.js b/jstests/sharding/resharding_feature_flagging.js
index 6e964a2237c..8b023168865 100644
--- a/jstests/sharding/resharding_feature_flagging.js
+++ b/jstests/sharding/resharding_feature_flagging.js
@@ -46,7 +46,7 @@ assert.commandFailedWithCode(
 
 const serverStatusCmd = ({serverStatus: 1, shardingStatistics: 1});
 let res = assert.commandWorked(configPrimary.adminCommand(serverStatusCmd));
-assert(!res.hasOwnProperty("shardingStatistics"), res.shardingStatistics);
+assert(!res.shardingStatistics.hasOwnProperty("resharding"), res.shardingStatistics);
 
 const shardPrimary = st.shard0.rs.getPrimary();
 res = assert.commandWorked(shardPrimary.adminCommand(serverStatusCmd));
diff --git a/jstests/sharding/resharding_metrics.js b/jstests/sharding/resharding_metrics.js
index c4cedb11711..7e1d3a830a2 100644
--- a/jstests/sharding/resharding_metrics.js
+++ b/jstests/sharding/resharding_metrics.js
@@ -50,8 +50,7 @@ function testMetricsArePresent(mongo, expectedMetrics, minOplogEntriesFetchedAnd
 
 function verifyStatsMissing(mongo) {
     const stats = mongo.getDB('admin').serverStatus({});
-    assert(!stats.hasOwnProperty('shardingStatistics') ||
-               !stats.shardingStatistics.hasOwnProperty('resharding'),
+    assert(!stats.shardingStatistics.hasOwnProperty('resharding'),
            `Resharding section not expected in ${tojson(stats)}`);
 }
 
diff --git a/jstests/sharding/sharding_statistics_server_status.js b/jstests/sharding/sharding_statistics_server_status.js
index 67e22039403..a9a4f6a273d 100644
--- a/jstests/sharding/sharding_statistics_server_status.js
+++ b/jstests/sharding/sharding_statistics_server_status.js
@@ -64,6 +64,13 @@ function checkServerStatusAbortedMigrationCount(shardConn, count) {
     assert.eq(count, shardStats.countDonorMoveChunkAbortConflictingIndexOperation);
 }
 
+function checkServerStatusNumShardedCollections(conn, count) {
+    const shardStats =
+        assert.commandWorked(conn.adminCommand({serverStatus: 1})).shardingStatistics;
+    assert(shardStats.hasOwnProperty("numShardedCollections"));
+    assert.eq(count, shardStats.numShardedCollections);
+}
+
 function runConcurrentMoveChunk(host, ns, toShard) {
     const mongos = new Mongo(host);
     // Helper function to run moveChunk, retrying on ConflictingOperationInProgress. We need to
@@ -132,6 +139,17 @@ st.ensurePrimaryShard(coll.getDB() + "", st.shard0.shardName);
 assert.commandWorked(admin.runCommand({shardCollection: coll + "", key: {_id: 1}}));
 assert.commandWorked(admin.runCommand({split: coll + "", middle: {_id: 0}}));
 
+// Check the number of sharded collections.
+const testDB = st.rs0.getPrimary().getDB(dbName);
+const fcvDoc = testDB.adminCommand({getParameter: 1, featureCompatibilityVersion: 1});
+if (MongoRunner.compareBinVersions(fcvDoc.featureCompatibilityVersion.version, '6.0') >= 0) {
+    st.shardColl(dbName + ".coll2", {_id: 1}, false);
+    st.shardColl(dbName + ".coll3", {_id: 1}, false);
+    const configCollections = mongos.getCollection("config.collections");
+    checkServerStatusNumShardedCollections(st.configRS.getPrimary(),
+                                           configCollections.countDocuments({}));
+}
+
 // Move chunk from shard0 to shard1 without docs.
 assert.commandWorked(
     mongos.adminCommand({moveChunk: coll + '', find: {_id: 1}, to: st.shard1.shardName}));
diff --git a/src/mongo/db/s/sharding_server_status.cpp b/src/mongo/db/s/sharding_server_status.cpp
index 5a331364032..a6728345834 100644
--- a/src/mongo/db/s/sharding_server_status.cpp
+++ b/src/mongo/db/s/sharding_server_status.cpp
@@ -31,6 +31,7 @@
 
 #include "mongo/bson/bsonobjbuilder.h"
 #include "mongo/db/commands/server_status.h"
+#include "mongo/db/db_raii.h"
 #include "mongo/db/s/active_migrations_registry.h"
 #include "mongo/db/s/collection_sharding_state.h"
 #include "mongo/db/s/resharding/resharding_metrics.h"
@@ -123,6 +124,16 @@ public:
             CollectionShardingState::appendInfoForServerStatus(opCtx, &result);
         }
 
+        // To calculate the number of sharded collection we simply get the number of records from
+        // `config.collections` collection. This count must only be appended when serverStatus is
+        // invoked on the config server.
+        if (serverGlobalParams.clusterRole == ClusterRole::ConfigServer) {
+            AutoGetCollectionForRead autoColl(opCtx, CollectionType::ConfigNS);
+            const auto& collection = autoColl.getCollection();
+            const auto numShardedCollections = collection ? collection->numRecords(opCtx) : 0;
+            result.append("numShardedCollections", numShardedCollections);
+        }
+
         // The serverStatus command is run before the FCV is initialized so we ignore it when
         // checking whether the resharding feature is enabled here.
         if (resharding::gFeatureFlagResharding.isEnabledAndIgnoreFCV()) {