SERVER-43310 Always route a sharded cluster's createIndexes call through a replica set's primary node

4 files changed, 24 insertions, 2 deletions

diff --git a/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml b/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml
index 955c59d77a7..8b810c50164 100644
--- a/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml
+++ b/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml
@@ -23,6 +23,8 @@ selector:
   - jstests/sharding/merge_from_stale_mongos.js
   # Enable when SERVER-44733 is backported
   - jstests/sharding/change_streams_update_lookup_shard_metadata_missing.js
+  # Enable when SERVER-43310 is backported
+  - jstests/sharding/cluster_create_indexes_always_routes_through_primary.js
 
 executor:
   config:
diff --git a/jstests/sharding/cluster_create_indexes_always_routes_through_primary.js b/jstests/sharding/cluster_create_indexes_always_routes_through_primary.js
new file mode 100644
index 00000000000..6c661e0abac
--- /dev/null
+++ b/jstests/sharding/cluster_create_indexes_always_routes_through_primary.js
@@ -0,0 +1,20 @@
+// Ensure that a call to createIndexes in a sharded cluster will route to the primary, even when
+// setSlaveOk() is set to true.
+(function() {
+'use strict';
+
+let st = new ShardingTest({shards: {rs0: {nodes: 2}}});
+const testDBName = jsTestName();
+const collName = 'coll';
+const testDB = st.s.getDB(testDBName);
+
+assert.commandWorked(testDB.adminCommand({enableSharding: testDBName}));
+assert.commandWorked(
+    testDB.adminCommand({shardCollection: testDB[collName].getFullName(), key: {x: 1}}));
+
+st.s.setSlaveOk(true);
+assert.commandWorked(
+    testDB.runCommand({createIndexes: collName, indexes: [{key: {a: 1}, name: "index"}]}));
+
+st.stop();
+})();
diff --git a/src/mongo/db/sessions_collection_config_server.cpp b/src/mongo/db/sessions_collection_config_server.cpp
index a246806cb7c..892686fb26b 100644
--- a/src/mongo/db/sessions_collection_config_server.cpp
+++ b/src/mongo/db/sessions_collection_config_server.cpp
@@ -92,7 +92,7 @@ void SessionsCollectionConfigServer::_generateIndexesIfNeeded(OperationContext*
                     nss,
                     routingInfo,
                     SessionsCollection::generateCreateIndexesCmd(),
-                    ReadPreferenceSetting::get(opCtx),
+                    ReadPreferenceSetting(ReadPreference::PrimaryOnly),
                     Shard::RetryPolicy::kNoRetry,
                     BSONObj() /* query */,
                     BSONObj() /* collation */);
diff --git a/src/mongo/s/commands/cluster_create_indexes_cmd.cpp b/src/mongo/s/commands/cluster_create_indexes_cmd.cpp
index cffbd636e71..affdf4e583f 100644
--- a/src/mongo/s/commands/cluster_create_indexes_cmd.cpp
+++ b/src/mongo/s/commands/cluster_create_indexes_cmd.cpp
@@ -83,7 +83,7 @@ public:
             routingInfo,
             CommandHelpers::filterCommandRequestForPassthrough(
                 applyReadWriteConcern(opCtx, this, cmdObj)),
-            ReadPreferenceSetting::get(opCtx),
+            ReadPreferenceSetting(ReadPreference::PrimaryOnly),
             Shard::RetryPolicy::kNoRetry,
             BSONObj() /* query */,
             BSONObj() /* collation */);