delay initial NEG GC by one GC period

cmd/glbc/main.go

@@ -184,7 +184,7 @@ func runControllers(ctx *context.ControllerContext) {
 
 	if ctx.NEGEnabled {
 		// TODO: Refactor NEG to use cloud mocks so ctx.Cloud can be referenced within NewController.
-		negController := neg.NewController(neg.NewAdapter(ctx.Cloud), ctx, lbc.Translator, ctx.ClusterNamer, flags.F.ResyncPeriod)
+		negController := neg.NewController(neg.NewAdapter(ctx.Cloud), ctx, lbc.Translator, ctx.ClusterNamer, flags.F.ResyncPeriod, flags.F.NegGCPeriod)
 		go negController.Run(stopCh)
 		glog.V(0).Infof("negController started")
 	}

pkg/flags/flags.go

@@ -81,6 +81,7 @@ var (
 		WatchNamespace            string
 		NodePortRanges            PortRanges
 		EnableBackendConfig       bool
+		NegGCPeriod               time.Duration
 
 		LeaderElection LeaderElectionConfiguration
 	}{}
@@ -215,6 +216,8 @@ L7 load balancing. CSV values accepted. Example: -node-port-ranges=80,8080,400-5
 		`This flag is deprecated. Use -v to control verbosity.`)
 	flag.Bool("use-real-cloud", false,
 		`This flag has been deprecated and no longer has any effect.`)
+	flag.DurationVar(&F.NegGCPeriod, "neg-gc-period", 120*time.Second,
+		`Relist and garbage collect NEGs this often.`)
 }
 
 type RateLimitSpecs struct {

pkg/neg/controller.go

@@ -40,11 +40,6 @@ import (
 	"k8s.io/ingress-gce/pkg/utils"
 )
 
-const (
-	// gcPeriod is the interval between NEG garbage collection workflows
-	gcPeriod = 2 * time.Minute
-)
-
 func init() {
 	// register prometheus metrics
 	registerMetrics()
@@ -55,6 +50,7 @@ func init() {
 type Controller struct {
 	manager      negSyncerManager
 	resyncPeriod time.Duration
+	gcPeriod     time.Duration
 	recorder     record.EventRecorder
 	namer        networkEndpointGroupNamer
 	zoneGetter   zoneGetter
@@ -79,7 +75,8 @@ func NewController(
 	ctx *context.ControllerContext,
 	zoneGetter zoneGetter,
 	namer networkEndpointGroupNamer,
-	resyncPeriod time.Duration) *Controller {
+	resyncPeriod time.Duration,
+	gcPeriod time.Duration) *Controller {
 	// init event recorder
 	// TODO: move event recorder initializer to main. Reuse it among controllers.
 	eventBroadcaster := record.NewBroadcaster()
@@ -96,6 +93,7 @@ func NewController(
 		client:         ctx.KubeClient,
 		manager:        manager,
 		resyncPeriod:   resyncPeriod,
+		gcPeriod:       gcPeriod,
 		recorder:       recorder,
 		zoneGetter:     zoneGetter,
 		namer:          namer,
@@ -172,7 +170,12 @@ func (c *Controller) Run(stopCh <-chan struct{}) {
 	}()
 
 	go wait.Until(c.serviceWorker, time.Second, stopCh)
-	go wait.Until(c.gc, gcPeriod, stopCh)
+	go func() {
+		// Wait for gcPeriod to run the first GC
+		// This is to make sure that all services are fully processed before running GC.
+		time.Sleep(c.gcPeriod)
+		wait.Until(c.gc, c.gcPeriod, stopCh)
+	}()
 
 	<-stopCh
 }

pkg/neg/controller_test.go

@@ -60,6 +60,7 @@ func newTestController(kubeClient kubernetes.Interface) *Controller {
 		NewFakeZoneGetter(),
 		namer,
 		1*time.Second,
+		1*time.Second,
 	)
 	return controller
 }