Use target credentials for control-replica throttling in move-tables mode

Author: danieljoos

go/cmd/gh-ost/main.go

@@ -134,7 +134,7 @@ func main() {
 
 	maxLagMillis := flag.Int64("max-lag-millis", 1500, "replication lag at which to throttle operation")
 	replicationLagQuery := flag.String("replication-lag-query", "", "Deprecated. gh-ost uses an internal, subsecond resolution query")
-	throttleControlReplicas := flag.String("throttle-control-replicas", "", "List of replicas on which to check for lag; comma delimited. Example: myhost1.com:3306,myhost2.com,myhost3.com:3307")
+	throttleControlReplicas := flag.String("throttle-control-replicas", "", "List of replicas on which to check for lag; comma delimited. Example: myhost1.com:3306,myhost2.com,myhost3.com:3307. In move-tables mode, these replicas are expected to be in the target cluster. Specified target credentials will be used for the connection.")
 	throttleQuery := flag.String("throttle-query", "", "when given, issued (every second) to check if operation should throttle. Expecting to return zero for no-throttle, >0 for throttle. Query is issued on the migrated server. Make sure this query is lightweight")
 	throttleHTTP := flag.String("throttle-http", "", "when given, gh-ost checks given URL via HEAD request; any response code other than 200 (OK) causes throttling; make sure it has low latency response")
 	flag.Int64Var(&migrationContext.ThrottleHTTPIntervalMillis, "throttle-http-interval-millis", 100, "Number of milliseconds to wait before triggering another HTTP throttle check")

go/logic/throttler.go

@@ -213,7 +213,13 @@ func (thlr *Throttler) collectControlReplicasLag() {
 		}
 		lagResults := make(chan *mysql.ReplicationLagResult, instanceKeyMap.Len())
 		for replicaKey := range *instanceKeyMap {
-			connectionConfig := thlr.migrationContext.InspectorConnectionConfig.DuplicateCredentials(replicaKey)
+			var connectionConfig *mysql.ConnectionConfig
+			if thlr.migrationContext.IsMoveTablesMode() {
+				connectionConfig = thlr.migrationContext.MoveTables.ConnectionConfig.DuplicateCredentials(replicaKey)
+			} else {
+				connectionConfig = thlr.migrationContext.InspectorConnectionConfig.DuplicateCredentials(replicaKey)
+			}
+
 			if err := connectionConfig.RegisterTLSConfig(); err != nil {
 				return &mysql.ReplicationLagResult{Err: err}
 			}