SERVER-32636 Close outgoing connections to earlier binVersion servers

3 files changed, 20 insertions, 5 deletions

diff --git a/src/mongo/db/commands/feature_compatibility_version.cpp b/src/mongo/db/commands/feature_compatibility_version.cpp
index c0edc6a028e..b64a072dc4b 100644
--- a/src/mongo/db/commands/feature_compatibility_version.cpp
+++ b/src/mongo/db/commands/feature_compatibility_version.cpp
@@ -43,6 +43,7 @@
 #include "mongo/db/storage/storage_engine.h"
 #include "mongo/db/wire_version.h"
 #include "mongo/db/write_concern_options.h"
+#include "mongo/executor/egress_tag_closer_manager.h"
 #include "mongo/rpc/get_status_from_command_result.h"
 #include "mongo/transport/service_entry_point.h"
 #include "mongo/util/log.h"
@@ -268,19 +269,21 @@ void FeatureCompatibilityVersion::onInsertOrUpdate(OperationContext* opCtx, cons
         log() << "setting featureCompatibilityVersion to " << toString(newVersion);
     }
 
-    // On commit, update the server parameters, and close any incoming connections with a wire
-    // version that is below the minimum.
+    // On commit, update the server parameters, and close any connections with a wire version that
+    // is below the minimum.
     opCtx->recoveryUnit()->onCommit([opCtx, newVersion]() {
         serverGlobalParams.featureCompatibility.setVersion(newVersion);
         updateMinWireVersion();
 
-        // Close all incoming connections from internal clients with binary versions lower than
-        // ours. It would be desirable to close all outgoing connections to servers with lower
-        // binary version, but it is not currently possible.
         if (newVersion != ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo36) {
+            // Close all incoming connections from internal clients with binary versions lower than
+            // ours.
             opCtx->getServiceContext()->getServiceEntryPoint()->endAllSessions(
                 transport::Session::kLatestVersionInternalClientKeepOpen |
                 transport::Session::kExternalClientKeepOpen);
+            // Close all outgoing connections to servers with binary versions lower than ours.
+            executor::EgressTagCloserManager::get(opCtx->getServiceContext())
+                .dropConnections(transport::Session::kKeepOpen);
         }
     });
 }
diff --git a/src/mongo/executor/SConscript b/src/mongo/executor/SConscript
index bea86e323cd..561155ec335 100644
--- a/src/mongo/executor/SConscript
+++ b/src/mongo/executor/SConscript
@@ -179,6 +179,7 @@ env.Library(
         'async_stream',
         'async_timer_asio',
         'connection_pool_executor',
+        'egress_tag_closer_manager',
         'network_interface',
         'task_executor_interface',
     ])
diff --git a/src/mongo/executor/network_interface_asio_auth.cpp b/src/mongo/executor/network_interface_asio_auth.cpp
index 3ed78167d0a..88d9aeae29e 100644
--- a/src/mongo/executor/network_interface_asio_auth.cpp
+++ b/src/mongo/executor/network_interface_asio_auth.cpp
@@ -116,6 +116,17 @@ void NetworkInterfaceASIO::_runIsMaster(AsyncOp* op) {
 
             return _completeOperation(op, validateStatus);
         }
+        auto egressTagManager = _options.connectionPoolOptions.egressTagCloserManager;
+        if (egressTagManager) {
+            // Tag outgoing connection so it can be kept open on FCV upgrade if it is not to a
+            // server with a lower binary version.
+            if (protocolSet.getValue().version.maxWireVersion >=
+                WireSpec::instance().outgoing.maxWireVersion) {
+                egressTagManager->mutateTags(
+                    op->command().target(),
+                    [](transport::Session::TagMask tags) { return transport::Session::kKeepOpen; });
+            }
+        }  // Some unit and integration tests do not set up an egress tag manager.
 
         op->connection().setServerProtocols(protocolSet.getValue().protocolSet);