PYTHON-4117 Require 4.3.1+ server version when using failCommand errorLabels option (mongodb#1526)

Author: blink1073

pymongo/helpers.py

@@ -254,6 +254,8 @@ def _get_wce_doc(result: Mapping[str, Any]) -> Optional[Mapping[str, Any]]:
         # convenient to attach it to the writeConcernError doc itself.
         error_labels = result.get("errorLabels")
         if error_labels:
+            # Copy to avoid changing the original document.
+            wce = wce.copy()
             wce["errorLabels"] = error_labels
     return wce
 

pymongo/mongo_client.py

@@ -83,6 +83,7 @@
     PyMongoError,
     ServerSelectionTimeoutError,
     WaitQueueTimeoutError,
+    WriteConcernError,
 )
 from pymongo.lock import _HAS_REGISTER_AT_FORK, _create_lock, _release_locks
 from pymongo.monitoring import ConnectionClosedReason
@@ -2175,7 +2176,7 @@ def _retryable_error_doc(exc: PyMongoError) -> Optional[Mapping[str, Any]]:
     return None
 
 
-def _add_retryable_write_error(exc: PyMongoError, max_wire_version: int) -> None:
+def _add_retryable_write_error(exc: PyMongoError, max_wire_version: int, is_mongos: bool) -> None:
     doc = _retryable_error_doc(exc)
     if doc:
         code = doc.get("code", 0)
@@ -2192,7 +2193,10 @@ def _add_retryable_write_error(exc: PyMongoError, max_wire_version: int) -> None
             for label in doc.get("errorLabels", []):
                 exc._add_error_label(label)
         else:
-            if code in helpers._RETRYABLE_ERROR_CODES:
+            # Do not consult writeConcernError for pre-4.4 mongos.
+            if isinstance(exc, WriteConcernError) and is_mongos:
+                pass
+            elif code in helpers._RETRYABLE_ERROR_CODES:
                 exc._add_error_label("RetryableWriteError")
 
     # Connection errors are always retryable except NotPrimaryError and WaitQueueTimeoutError which is
@@ -2432,6 +2436,7 @@ def _write(self) -> T:
         """
         try:
             max_wire_version = 0
+            is_mongos = False
             self._server = self._get_server()
             with self._client._checkout(self._server, self._session) as conn:
                 max_wire_version = conn.max_wire_version
@@ -2440,6 +2445,7 @@ def _write(self) -> T:
                     and self._server.description.retryable_writes_supported
                     and conn.supports_sessions
                 )
+                is_mongos = conn.is_mongos
                 if not sessions_supported:
                     # A retry is not possible because this server does
                     # not support sessions raise the last error.
@@ -2450,7 +2456,7 @@ def _write(self) -> T:
             if not self._retryable:
                 raise
             # Add the RetryableWriteError label, if applicable.
-            _add_retryable_write_error(exc, max_wire_version)
+            _add_retryable_write_error(exc, max_wire_version, is_mongos)
             raise
 
     def _read(self) -> T:

test/command_monitoring/writeConcernError.json

@@ -3,7 +3,7 @@
   "schemaVersion": "1.4",
   "runOnRequirements": [
     {
-      "minServerVersion": "4.1.0",
+      "minServerVersion": "4.3.1",
       "topologies": [
         "replicaset"
       ],
@@ -66,11 +66,11 @@
                 "failCommands": [
                   "insert"
                 ],
+                "errorLabels": [
+                  "RetryableWriteError"
+                ],
                 "writeConcernError": {
-                  "code": 91,
-                  "errorLabels": [
-                    "RetryableWriteError"
-                  ]
+                  "code": 91
                 }
               }
             }
@@ -112,11 +112,11 @@
                 "reply": {
                   "ok": 1,
                   "n": 1,
+                  "errorLabels": [
+                    "RetryableWriteError"
+                  ],
                   "writeConcernError": {
-                    "code": 91,
-                    "errorLabels": [
-                      "RetryableWriteError"
-                    ]
+                    "code": 91
                   }
                 },
                 "commandName": "insert"
@@ -152,4 +152,4 @@
       ]
     }
   ]
-}
+}