SERVER-34197 Only allow global snapshot reads when test commands are enabled

jstests/noPassthrough/readConcern_snapshot_mongos_enable_test_commands.js

@@ -0,0 +1,63 @@
+// Verifies that snapshot readConcern on mongos is gated by the enableTestCommands flag.
+//
+// @tags: [requires_sharding]
+(function() {
+    "use strict";
+
+    const dbName = "test";
+    const collName = "coll";
+
+    // Snapshot readConcern should fail when 'enableTestCommands' is set to false.
+    {
+        jsTest.setOption("enableTestCommands", false);
+
+        const st = new ShardingTest({shards: 1, config: 1});
+        const session = st.s.startSession({causalConsistency: false});
+        let txnNumber = 0;
+
+        assert.commandFailedWithCode(session.getDatabase(dbName).runCommand({
+            find: collName,
+            readConcern: {level: "snapshot"},
+            txnNumber: NumberLong(txnNumber++)
+        }),
+                                     ErrorCodes.InvalidOptions);
+
+        assert.commandFailedWithCode(session.getDatabase(dbName).runCommand({
+            aggregate: collName,
+            pipeline: [],
+            cursor: {},
+            readConcern: {level: "snapshot"},
+            txnNumber: NumberLong(txnNumber++)
+        }),
+                                     ErrorCodes.InvalidOptions);
+
+        session.endSession();
+        st.stop();
+    }
+
+    // Snapshot readConcern should succeed when 'enableTestCommands' is set to true.
+    {
+        jsTest.setOption("enableTestCommands", true);
+
+        const st = new ShardingTest({shards: 1, config: 1});
+        const session = st.s.startSession({causalConsistency: false});
+        let txnNumber = 0;
+
+        assert.commandWorked(session.getDatabase(dbName).runCommand({
+            find: collName,
+            readConcern: {level: "snapshot"},
+            txnNumber: NumberLong(txnNumber++)
+        }));
+
+        assert.commandWorked(session.getDatabase(dbName).runCommand({
+            aggregate: collName,
+            pipeline: [],
+            cursor: {},
+            readConcern: {level: "snapshot"},
+            txnNumber: NumberLong(txnNumber++)
+        }));
+
+        session.endSession();
+        st.stop();
+    }
+}());

src/mongo/s/SConscript

@@ -285,6 +285,7 @@ env.Library(
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
+        '$BUILD_DIR/mongo/db/commands/test_commands_enabled',
         '$BUILD_DIR/mongo/executor/thread_pool_task_executor',
         '$BUILD_DIR/mongo/s/client/sharding_client',
         'cluster_last_error_info',

src/mongo/s/commands/strategy.cpp

@@ -41,6 +41,7 @@
 #include "mongo/db/auth/action_type.h"
 #include "mongo/db/auth/authorization_session.h"
 #include "mongo/db/commands.h"
+#include "mongo/db/commands/test_commands_enabled.h"
 #include "mongo/db/curop.h"
 #include "mongo/db/initialize_operation_session_info.h"
 #include "mongo/db/lasterror.h"
@@ -217,6 +218,10 @@ void execCommandClient(OperationContext* opCtx,
     auto& readConcernArgs = repl::ReadConcernArgs::get(opCtx);
 
     if (readConcernArgs.getLevel() == repl::ReadConcernLevel::kSnapshotReadConcern) {
+        uassert(ErrorCodes::InvalidOptions,
+                "readConcern level snapshot is not supported on mongos",
+                getTestCommandsEnabled());
+
         // TODO SERVER-33708.
         if (!invocation->supportsReadConcern(readConcernArgs.getLevel())) {
             auto body = result->getBodyBuilder();

src/mongo/s/sharding_task_executor.cpp

@@ -35,6 +35,7 @@
 #include "mongo/base/disallow_copying.h"
 #include "mongo/base/status_with.h"
 #include "mongo/bson/timestamp.h"
+#include "mongo/db/commands/test_commands_enabled.h"
 #include "mongo/db/logical_time.h"
 #include "mongo/db/operation_time_tracker.h"
 #include "mongo/executor/thread_pool_task_executor.h"
@@ -131,7 +132,8 @@ StatusWith<TaskExecutor::CallbackHandle> ShardingTaskExecutor::scheduleRemoteCom
         }
 
         // TODO SERVER-33991.
-        if (request.opCtx->getTxnNumber() && request.cmdObj.hasField("getMore") &&
+        if (getTestCommandsEnabled() && request.opCtx->getTxnNumber() &&
+            request.cmdObj.hasField("getMore") &&
             !request.cmdObj.hasField(OperationSessionInfo::kTxnNumberFieldName)) {
             bob.append(OperationSessionInfo::kTxnNumberFieldName, *(request.opCtx->getTxnNumber()));
         }