SERVER-75368 Set cluster parameter during FCV upgrade

2 files changed, 94 insertions, 0 deletions

diff --git a/jstests/sharding/check_for_direct_shard_ops_upgrade_downgrade.js b/jstests/sharding/check_for_direct_shard_ops_upgrade_downgrade.js
new file mode 100644
index 00000000000..36de3f7f1a7
--- /dev/null
+++ b/jstests/sharding/check_for_direct_shard_ops_upgrade_downgrade.js
@@ -0,0 +1,49 @@
+/**
+ * Tests that the cluster parameter "shardedClusterCardinalityForDirectConns" has the correct value
+ * after upgrade and downgrade.
+ *
+ * @tags: [multiversion_incompatible, featureFlagCheckForDirectShardOperations,
+ * temporary_catalog_shard_incompatible]
+ */
+
+(function() {
+'use strict';
+
+load("jstests/sharding/libs/remove_shard_util.js");
+
+const st = new ShardingTest({shards: 1, useHostname: false});
+
+const additionalShard = new ReplSetTest({name: "additionalShard", host: 'localhost', nodes: 1});
+additionalShard.startSet({shardsvr: ""});
+additionalShard.initiate();
+
+let checkClusterParameter = function(conn, expectedValue) {
+    let resp = assert.commandWorked(
+        conn.adminCommand({getClusterParameter: "shardedClusterCardinalityForDirectConns"}));
+    assert.eq(resp.clusterParameters[0].hasTwoOrMoreShards, expectedValue);
+};
+
+// There is only one shard in the cluster, so the cluster parameter should be false
+checkClusterParameter(st.configRS.getPrimary(), false);
+checkClusterParameter(st.shard0, false);
+
+assert.commandWorked(st.s.adminCommand({setFeatureCompatibilityVersion: lastLTSFCV}));
+assert.commandWorked(st.s.adminCommand({addShard: additionalShard.getURL(), name: "shard02"}));
+assert.commandWorked(st.s.adminCommand({setFeatureCompatibilityVersion: latestFCV}));
+
+// There are two shards in the cluster while upgrading, so the cluster parameter should be true
+checkClusterParameter(st.configRS.getPrimary(), true);
+checkClusterParameter(st.shard0, true);
+checkClusterParameter(additionalShard.getPrimary(), true);
+
+assert.commandWorked(st.s.adminCommand({setFeatureCompatibilityVersion: lastLTSFCV}));
+removeShard(st, "shard02");
+assert.commandWorked(st.s.adminCommand({setFeatureCompatibilityVersion: latestFCV}));
+
+// There is one shard in the cluster while upgrading, so the cluster parameter should be false
+checkClusterParameter(st.configRS.getPrimary(), false);
+checkClusterParameter(st.shard0, false);
+
+additionalShard.stopSet();
+st.stop();
+})();
diff --git a/src/mongo/db/commands/set_feature_compatibility_version_command.cpp b/src/mongo/db/commands/set_feature_compatibility_version_command.cpp
index b7b4b8a38c9..c8c7a2a33ef 100644
--- a/src/mongo/db/commands/set_feature_compatibility_version_command.cpp
+++ b/src/mongo/db/commands/set_feature_compatibility_version_command.cpp
@@ -74,6 +74,7 @@
 #include "mongo/db/s/resharding/resharding_coordinator_service.h"
 #include "mongo/db/s/resharding/resharding_donor_recipient_common.h"
 #include "mongo/db/s/shard_authoritative_catalog_gen.h"
+#include "mongo/db/s/sharding_cluster_parameters_gen.h"
 #include "mongo/db/s/sharding_ddl_coordinator_service.h"
 #include "mongo/db/s/sharding_index_catalog_ddl_util.h"
 #include "mongo/db/s/sharding_state.h"
@@ -91,6 +92,8 @@
 #include "mongo/rpc/get_status_from_command_result.h"
 #include "mongo/s/catalog/type_config_version.h"
 #include "mongo/s/catalog/type_index_catalog.h"
+#include "mongo/s/grid.h"
+#include "mongo/s/request_types/sharded_ddl_commands_gen.h"
 #include "mongo/s/sharding_feature_flags_gen.h"
 #include "mongo/stdx/unordered_set.h"
 #include "mongo/util/exit.h"
@@ -690,6 +693,7 @@ private:
             // Depends on _setOnCurrentShardSinceFieldOnChunks()
             _initializePlacementHistory(opCtx, requestedVersion, actualVersion);
             _dropConfigMigrationsCollection(opCtx);
+            _setShardedClusterCardinalityParam(opCtx, requestedVersion);
         }
 
         _removeRecordPreImagesCollectionOption(opCtx);
@@ -804,6 +808,47 @@ private:
         }
     }
 
+    void _setShardedClusterCardinalityParam(
+        OperationContext* opCtx, const multiversion::FeatureCompatibilityVersion requestedVersion) {
+        if (feature_flags::gCheckForDirectShardOperations.isEnabledOnVersion(requestedVersion)) {
+            // Get current cluster parameter value so that we don't run SetClusterParameter
+            // extraneously
+            auto* clusterParameters = ServerParameterSet::getClusterParameterSet();
+            auto* clusterCardinalityParam =
+                clusterParameters->get<ClusterParameterWithStorage<ShardedClusterCardinalityParam>>(
+                    "shardedClusterCardinalityForDirectConns");
+            auto currentValue =
+                clusterCardinalityParam->getValue(boost::none).getHasTwoOrMoreShards();
+
+            // config.shards is stable during FCV changes, so query that to discover the current
+            // number of shards.
+            DBDirectClient client(opCtx);
+            FindCommandRequest findRequest{NamespaceString::kConfigsvrShardsNamespace};
+            findRequest.setLimit(2);
+            auto numShards = client.find(std::move(findRequest))->itcount();
+            bool expectedValue = numShards >= 2;
+
+            if (expectedValue == currentValue) {
+                return;
+            }
+
+            ConfigsvrSetClusterParameter configsvrSetClusterParameter(
+                BSON("shardedClusterCardinalityForDirectConns"
+                     << BSON("hasTwoOrMoreShards" << expectedValue)));
+            configsvrSetClusterParameter.setDbName(DatabaseName(boost::none, "admin"));
+
+            const auto shardRegistry = Grid::get(opCtx)->shardRegistry();
+            const auto cmdResponse =
+                uassertStatusOK(shardRegistry->getConfigShard()->runCommandWithFixedRetryAttempts(
+                    opCtx,
+                    ReadPreferenceSetting(ReadPreference::PrimaryOnly),
+                    DatabaseName::kAdmin.toString(),
+                    configsvrSetClusterParameter.toBSON({}),
+                    Shard::RetryPolicy::kIdempotent));
+            uassertStatusOK(Shard::CommandResponse::getEffectiveStatus(std::move(cmdResponse)));
+        }
+    }
+
     // TODO (SERVER-72791): Remove once FCV 7.0 becomes last-lts.
     void _setOnCurrentShardSinceFieldOnChunks(
         OperationContext* opCtx,