replication: send VolumeReplication operations to the leading controller

Just like NetworkFence operations should be sent to a preferred
Controller Server, VolumeReplication operations should be sent
there as well.

Updates: #422
Signed-off-by: Niels de Vos <ndevos@ibm.com>

Author: nixpanic

controllers/replication.storage/volumereplication_controller.go

@@ -174,7 +174,7 @@ func (r *VolumeReplicationReconciler) Reconcile(ctx context.Context, req ctrl.Re
 		logger.Info("Replication handle", "ReplicationHandleName", replicationHandle)
 	}
 
-	replicationClient, err := r.getReplicationClient(vrcObj.Spec.Provisioner)
+	replicationClient, err := r.getReplicationClient(ctx, vrcObj.Spec.Provisioner)
 	if err != nil {
 		logger.Error(err, "Failed to get ReplicationClient")
 
@@ -453,27 +453,25 @@ func getInfoReconcileInterval(parameters map[string]string, logger logr.Logger)
 	return scheduleTime / 2
 }
 
-func (r *VolumeReplicationReconciler) getReplicationClient(driverName string) (grpcClient.VolumeReplication, error) {
-	conns := r.Connpool.GetByNodeID(driverName, "")
-
-	// Iterate through the connections and find the one that matches the driver name
-	// provided in the VolumeReplication spec; so that corresponding
-	// operations can be performed.
-	for _, v := range conns {
-		for _, cap := range v.Capabilities {
-			// validate if VOLUME_REPLICATION capability is supported by the driver.
-			if cap.GetVolumeReplication() == nil {
-				continue
-			}
+func (r *VolumeReplicationReconciler) getReplicationClient(ctx context.Context, driverName string) (grpcClient.VolumeReplication, error) {
+	conn, err := r.Connpool.GetLeaderByDriver(ctx, r.Client, driverName)
+	if err != nil {
+		return nil, fmt.Errorf("no leader for the ControllerService of driver %q", driverName)
+	}
 
-			// validate of VOLUME_REPLICATION capability is enabled by the storage driver.
-			if cap.GetVolumeReplication().GetType() == identity.Capability_VolumeReplication_VOLUME_REPLICATION {
-				return grpcClient.NewReplicationClient(v.Client, r.Timeout), nil
-			}
+	for _, cap := range conn.Capabilities {
+		// validate if VOLUME_REPLICATION capability is supported by the driver.
+		if cap.GetVolumeReplication() == nil {
+			continue
+		}
+
+		// validate of VOLUME_REPLICATION capability is enabled by the storage driver.
+		if cap.GetVolumeReplication().GetType() == identity.Capability_VolumeReplication_VOLUME_REPLICATION {
+			return grpcClient.NewReplicationClient(conn.Client, r.Timeout), nil
 		}
 	}
 
-	return nil, fmt.Errorf("no connections for driver: %s", driverName)
+	return nil, fmt.Errorf("leading CSIAddonsNode %q for driver %q does not support VolumeReplication", conn.Name, driverName)
 
 }