service controller: add OnAdd and OnDelete node event handlers

Signed-off-by: Andrew Sy Kim <kiman@vmware.com>

pkg/controller/service/controller.go

@@ -19,11 +19,10 @@ package service
 import (
 	"context"
 	"fmt"
+	"reflect"
 	"sync"
 	"time"
 
-	"reflect"
-
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/labels"
@@ -101,6 +100,7 @@ type serviceCache struct {
 type Controller struct {
 	cloud            cloudprovider.Interface
 	knownHosts       []*v1.Node
+	knownHostsLock   sync.Mutex
 	servicesToUpdate []*v1.Service
 	kubeClient       clientset.Interface
 	clusterName      string
@@ -175,6 +175,21 @@ func New(
 	s.serviceLister = serviceInformer.Lister()
 	s.serviceListerSynced = serviceInformer.Informer().HasSynced
 
+	nodeInformer.Informer().AddEventHandlerWithResyncPeriod(
+		cache.ResourceEventHandlerFuncs{
+			AddFunc: func(cur interface{}) {
+				s.nodeSyncLoop()
+			},
+			UpdateFunc: func(old, cur interface{}) {
+				s.nodeSyncLoop()
+			},
+			DeleteFunc: func(old interface{}) {
+				s.nodeSyncLoop()
+			},
+		},
+		time.Duration(0),
+	)
+
 	if err := s.init(); err != nil {
 		return nil, err
 	}
@@ -646,6 +661,8 @@ func getNodeConditionPredicate() NodeConditionPredicate {
 // nodeSyncLoop handles updating the hosts pointed to by all load
 // balancers whenever the set of nodes in the cluster changes.
 func (s *Controller) nodeSyncLoop() {
+	s.knownHostsLock.Lock()
+	defer s.knownHostsLock.Unlock()
 	newHosts, err := listWithPredicate(s.nodeLister, getNodeConditionPredicate())
 	if err != nil {
 		runtime.HandleError(fmt.Errorf("Failed to retrieve current set of nodes from node lister: %v", err))