Classify slot creation attempt on Postgres reader in multi-az

flow/alerting/classifier.go

@@ -185,6 +185,10 @@ var (
 	ErrorNotifyPostgresSlotMemalloc = ErrorClass{
 		Class: "NOTIFY_POSTGRES_SLOT_MEMALLOC", action: NotifyUser,
 	}
+	// This RDS specific error is seen when we try to create a replication slot on a read-replica
+	ErrNotifyPostgresCreatingSlotOnReader = ErrorClass{
+		Class: "NOTIFY_POSTGRES_CREATING_SLOT_ON_READER", action: NotifyUser,
+	}
 	// Mongo specific, equivalent to slot invalidation in Postgres
 	ErrorNotifyChangeStreamHistoryLost = ErrorClass{
 		Class: "NOTIFY_CHANGE_STREAM_HISTORY_LOST", action: NotifyUser,
@@ -497,6 +501,9 @@ func GetErrorClass(ctx context.Context, err error) (ErrorClass, ErrorInfo) {
 				return ErrorNotifyPostgresSlotMemalloc, pgErrorInfo
 			}
 
+			if strings.Contains(pgErr.Message, "Create the replication slot from the writer node instead") {
+				return ErrNotifyPostgresCreatingSlotOnReader, pgErrorInfo
+			}
 			// Fall through for other internal errors
 			return ErrorOther, pgErrorInfo
 

flow/alerting/classifier_test.go

@@ -291,6 +291,22 @@ func TestPostgresInvalidValueForSynchronizedStandbySlots(t *testing.T) {
 	}, errInfo, "Unexpected error info")
 }
 
+func TestPostgresCreatingSlotOnReader(t *testing.T) {
+	err := &pgconn.PgError{
+		Severity: "ERROR",
+		Code:     pgerrcode.InternalError,
+		Message: `ERROR: Creating logical replication slot peerflow_slot_mirror_1cd7f87b__d143__4cea__a247__a2acc5f5b746
+		is not supported on the Multi-AZ DB cluster reader node.
+		Create the replication slot from the writer node instead. (SQLSTATE XX000)`,
+	}
+	errorClass, errInfo := GetErrorClass(t.Context(), fmt.Errorf("slot error: [slot] error creating replication slot: %w", err))
+	assert.Equal(t, ErrNotifyPostgresCreatingSlotOnReader, errorClass, "Unexpected error class")
+	assert.Equal(t, ErrorInfo{
+		Source: ErrorSourcePostgres,
+		Code:   pgerrcode.InternalError,
+	}, errInfo, "Unexpected error info")
+}
+
 func TestPostgresStaleFileHandleErrorShouldBeRecoverable(t *testing.T) {
 	// Simulate a stale file handle error
 	err := &exceptions.PostgresWalError{