GC doesn't have to create monitors in the constructor

cmd/kube-controller-manager/app/BUILD

@@ -118,7 +118,6 @@ go_library(
         "//staging/src/k8s.io/apiserver/pkg/server/mux:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
         "//staging/src/k8s.io/client-go/discovery/cached:go_default_library",
-        "//staging/src/k8s.io/client-go/discovery/cached/memory:go_default_library",
         "//staging/src/k8s.io/client-go/dynamic:go_default_library",
         "//staging/src/k8s.io/client-go/informers:go_default_library",
         "//staging/src/k8s.io/client-go/informers/storage/v1:go_default_library",

cmd/kube-controller-manager/app/core.go

@@ -33,7 +33,6 @@ import (
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
-	cacheddiscovery "k8s.io/client-go/discovery/cached/memory"
 	storagev1informer "k8s.io/client-go/informers/storage/v1"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/metadata"
@@ -500,7 +499,6 @@ func startGarbageCollectorController(ctx ControllerContext) (http.Handler, bool,
 	}
 
 	gcClientset := ctx.ClientBuilder.ClientOrDie("generic-garbage-collector")
-	discoveryClient := cacheddiscovery.NewMemCacheClient(gcClientset.Discovery())
 
 	config := ctx.ClientBuilder.ConfigOrDie("generic-garbage-collector")
 	metadataClient, err := metadata.NewForConfig(config)
@@ -508,8 +506,6 @@ func startGarbageCollectorController(ctx ControllerContext) (http.Handler, bool,
 		return nil, true, err
 	}
 
-	// Get an initial set of deletable resources to prime the garbage collector.
-	deletableResources := garbagecollector.GetDeletableResources(discoveryClient)
 	ignoredResources := make(map[schema.GroupResource]struct{})
 	for _, r := range ctx.ComponentConfig.GarbageCollectorController.GCIgnoredResources {
 		ignoredResources[schema.GroupResource{Group: r.Group, Resource: r.Resource}] = struct{}{}
@@ -517,7 +513,6 @@ func startGarbageCollectorController(ctx ControllerContext) (http.Handler, bool,
 	garbageCollector, err := garbagecollector.NewGarbageCollector(
 		metadataClient,
 		ctx.RESTMapper,
-		deletableResources,
 		ignoredResources,
 		ctx.ObjectOrMetadataInformerFactory,
 		ctx.InformersStarted,

pkg/controller/garbagecollector/garbagecollector.go

@@ -76,7 +76,6 @@ type GarbageCollector struct {
 func NewGarbageCollector(
 	metadataClient metadata.Interface,
 	mapper resettableRESTMapper,
-	deletableResources map[schema.GroupVersionResource]struct{},
 	ignoredResources map[schema.GroupResource]struct{},
 	sharedInformers controller.InformerFactory,
 	informersStarted <-chan struct{},
@@ -91,7 +90,7 @@ func NewGarbageCollector(
 		attemptToOrphan:  attemptToOrphan,
 		absentOwnerCache: absentOwnerCache,
 	}
-	gb := &GraphBuilder{
+	gc.dependencyGraphBuilder = &GraphBuilder{
 		metadataClient:   metadataClient,
 		informersStarted: informersStarted,
 		restMapper:       mapper,
@@ -105,10 +104,6 @@ func NewGarbageCollector(
 		sharedInformers:  sharedInformers,
 		ignoredResources: ignoredResources,
 	}
-	if err := gb.syncMonitors(deletableResources); err != nil {
-		utilruntime.HandleError(fmt.Errorf("failed to sync all monitors: %v", err))
-	}
-	gc.dependencyGraphBuilder = gb
 
 	return gc, nil
 }

pkg/controller/garbagecollector/garbagecollector_test.go

@@ -81,12 +81,12 @@ func TestGarbageCollectorConstruction(t *testing.T) {
 	// construction will not fail.
 	alwaysStarted := make(chan struct{})
 	close(alwaysStarted)
-	gc, err := NewGarbageCollector(metadataClient, rm, twoResources, map[schema.GroupResource]struct{}{},
+	gc, err := NewGarbageCollector(metadataClient, rm, map[schema.GroupResource]struct{}{},
 		controller.NewInformerFactory(sharedInformers, metadataInformers), alwaysStarted)
 	if err != nil {
 		t.Fatal(err)
 	}
-	assert.Equal(t, 1, len(gc.dependencyGraphBuilder.monitors))
+	assert.Equal(t, 0, len(gc.dependencyGraphBuilder.monitors))
 
 	// Make sure resource monitor syncing creates and stops resource monitors.
 	tweakableRM.Add(schema.GroupVersionKind{Group: "tpr.io", Version: "v1", Kind: "unknown"}, nil)
@@ -198,12 +198,11 @@ func setupGC(t *testing.T, config *restclient.Config) garbageCollector {
 		t.Fatal(err)
 	}
 
-	podResource := map[schema.GroupVersionResource]struct{}{{Version: "v1", Resource: "pods"}: {}}
 	client := fake.NewSimpleClientset()
 	sharedInformers := informers.NewSharedInformerFactory(client, 0)
 	alwaysStarted := make(chan struct{})
 	close(alwaysStarted)
-	gc, err := NewGarbageCollector(metadataClient, &testRESTMapper{testrestmapper.TestOnlyStaticRESTMapper(legacyscheme.Scheme)}, podResource, ignoredResources, sharedInformers, alwaysStarted)
+	gc, err := NewGarbageCollector(metadataClient, &testRESTMapper{testrestmapper.TestOnlyStaticRESTMapper(legacyscheme.Scheme)}, ignoredResources, sharedInformers, alwaysStarted)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -827,13 +826,10 @@ func TestGarbageCollectorSync(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	podResource := map[schema.GroupVersionResource]struct{}{
-		{Group: "", Version: "v1", Resource: "pods"}: {},
-	}
 	sharedInformers := informers.NewSharedInformerFactory(client, 0)
 	alwaysStarted := make(chan struct{})
 	close(alwaysStarted)
-	gc, err := NewGarbageCollector(metadataClient, rm, podResource, map[schema.GroupResource]struct{}{}, sharedInformers, alwaysStarted)
+	gc, err := NewGarbageCollector(metadataClient, rm, map[schema.GroupResource]struct{}{}, sharedInformers, alwaysStarted)
 	if err != nil {
 		t.Fatal(err)
 	}

test/integration/garbagecollector/garbage_collector_test.go

@@ -232,7 +232,6 @@ func setupWithServer(t *testing.T, result *kubeapiservertesting.TestServer, work
 	discoveryClient := cacheddiscovery.NewMemCacheClient(clientSet.Discovery())
 	restMapper := restmapper.NewDeferredDiscoveryRESTMapper(discoveryClient)
 	restMapper.Reset()
-	deletableResources := garbagecollector.GetDeletableResources(discoveryClient)
 	config := *result.ClientConfig
 	metadataClient, err := metadata.NewForConfig(&config)
 	if err != nil {
@@ -249,7 +248,6 @@ func setupWithServer(t *testing.T, result *kubeapiservertesting.TestServer, work
 	gc, err := garbagecollector.NewGarbageCollector(
 		metadataClient,
 		restMapper,
-		deletableResources,
 		garbagecollector.DefaultIgnoredResources(),
 		controller.NewInformerFactory(sharedInformers, metadataInformers),
 		alwaysStarted,