node-controller reconcile node labels on each update

instead of waiting for the periodic loop of the node-controller to
go through all the nodes, use the sync logic to reconcile the node
labels each time that the node has changed after it has been
initialized.

This has the benefit that changes by external entities on this labels
are quickly reconciled.

Change-Id: I45cfc1e3f0b9eefdfdd67267229420d76132ab87

Kubernetes-commit: 0ab006b8a1e18b998e112b91fa5d7d868b577f68

controllers/node/node_controller.go

@@ -284,11 +284,6 @@ func (cnc *CloudNodeController) UpdateNodeStatus(ctx context.Context) error {
 		}
 
 		cnc.updateNodeAddress(ctx, node, instanceMetadata)
-
-		err = cnc.reconcileNodeLabels(node.Name)
-		if err != nil {
-			klog.Errorf("Error reconciling node labels for node %q, err: %v", node.Name, err)
-		}
 	}
 
 	workqueue.ParallelizeUntil(ctx, int(cnc.workerCount), len(nodes), updateNodeFunc)
@@ -424,9 +419,8 @@ func (cnc *CloudNodeController) syncNode(ctx context.Context, nodeName string) e
 
 	cloudTaint := getCloudTaint(curNode.Spec.Taints)
 	if cloudTaint == nil {
-		// Node object received from event had the cloud taint but was outdated,
-		// the node has actually already been initialized, so this sync event can be ignored.
-		return nil
+		// Node object was already initialized, only need to reconcile the labels
+		return cnc.reconcileNodeLabels(nodeName)
 	}
 
 	klog.Infof("Initializing node %s with cloud provider", nodeName)