Merge pull request #50583 from liggitt/endpoints-empty-noop

Automatic merge from submit-queue (batch tested with PRs 49869, 47987, 50211, 50804, 50583)

Make endpoints controller update based on semantic equality

Fixes #50828
Split from https://github.com/kubernetes/kubernetes/pull/45294 for separate review

Currently, endpoints objects containing no subsets are decoded by the go client as subsets:[] (when requested individually) or as subsets:null (when requested in a list of endpoints).

Because the endpoints controller is fed via a lister/watcher, it gets the `subsets:null` version fed to it. The subsets computation then returns an empty slice, which fails reflect.DeepEqual, which triggers a write attempt.

This PR makes the comparison use semantic.DeepEqual to avoid spurious writes.

https://github.com/kubernetes/kubernetes/pull/45294 would remove the inconsistency between lists and individual gets.

pkg/controller/endpoint/BUILD

@@ -20,6 +20,7 @@ go_library(
         "//pkg/util/metrics:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
         "//vendor/k8s.io/api/core/v1:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/api/equality:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/labels:go_default_library",

pkg/controller/endpoint/endpoints_controller.go

@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"k8s.io/api/core/v1"
+	apiequality "k8s.io/apimachinery/pkg/api/equality"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
@@ -434,8 +435,11 @@ func (e *EndpointController) syncService(key string) error {
 		}
 	}
 
-	if reflect.DeepEqual(currentEndpoints.Subsets, subsets) &&
-		reflect.DeepEqual(currentEndpoints.Labels, service.Labels) {
+	createEndpoints := len(currentEndpoints.ResourceVersion) == 0
+
+	if !createEndpoints &&
+		apiequality.Semantic.DeepEqual(currentEndpoints.Subsets, subsets) &&
+		apiequality.Semantic.DeepEqual(currentEndpoints.Labels, service.Labels) {
 		glog.V(5).Infof("endpoints are equal for %s/%s, skipping update", service.Namespace, service.Name)
 		return nil
 	}
@@ -451,7 +455,6 @@ func (e *EndpointController) syncService(key string) error {
 	}
 
 	glog.V(4).Infof("Update endpoints for %v/%v, ready: %d not ready: %d", service.Namespace, service.Name, totalReadyEps, totalNotReadyEps)
-	createEndpoints := len(currentEndpoints.ResourceVersion) == 0
 	if createEndpoints {
 		// No previous endpoints, create them
 		_, err = e.client.Core().Endpoints(service.Namespace).Create(newEndpoints)

pkg/controller/endpoint/endpoints_controller_test.go

@@ -175,6 +175,70 @@ func TestSyncEndpointsItemsPreserveNoSelector(t *testing.T) {
 	endpointsHandler.ValidateRequestCount(t, 0)
 }
 
+func TestSyncEndpointsExistingNilSubsets(t *testing.T) {
+	ns := metav1.NamespaceDefault
+	testServer, endpointsHandler := makeTestServer(t, ns)
+	defer testServer.Close()
+	endpoints := newController(testServer.URL)
+	endpoints.endpointsStore.Add(&v1.Endpoints{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:            "foo",
+			Namespace:       ns,
+			ResourceVersion: "1",
+		},
+		Subsets: nil,
+	})
+	endpoints.serviceStore.Add(&v1.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: ns},
+		Spec: v1.ServiceSpec{
+			Selector: map[string]string{"foo": "bar"},
+			Ports:    []v1.ServicePort{{Port: 80}},
+		},
+	})
+	endpoints.syncService(ns + "/foo")
+	endpointsHandler.ValidateRequestCount(t, 0)
+}
+
+func TestSyncEndpointsExistingEmptySubsets(t *testing.T) {
+	ns := metav1.NamespaceDefault
+	testServer, endpointsHandler := makeTestServer(t, ns)
+	defer testServer.Close()
+	endpoints := newController(testServer.URL)
+	endpoints.endpointsStore.Add(&v1.Endpoints{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:            "foo",
+			Namespace:       ns,
+			ResourceVersion: "1",
+		},
+		Subsets: []v1.EndpointSubset{},
+	})
+	endpoints.serviceStore.Add(&v1.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: ns},
+		Spec: v1.ServiceSpec{
+			Selector: map[string]string{"foo": "bar"},
+			Ports:    []v1.ServicePort{{Port: 80}},
+		},
+	})
+	endpoints.syncService(ns + "/foo")
+	endpointsHandler.ValidateRequestCount(t, 0)
+}
+
+func TestSyncEndpointsNewNoSubsets(t *testing.T) {
+	ns := metav1.NamespaceDefault
+	testServer, endpointsHandler := makeTestServer(t, ns)
+	defer testServer.Close()
+	endpoints := newController(testServer.URL)
+	endpoints.serviceStore.Add(&v1.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: ns},
+		Spec: v1.ServiceSpec{
+			Selector: map[string]string{"foo": "bar"},
+			Ports:    []v1.ServicePort{{Port: 80}},
+		},
+	})
+	endpoints.syncService(ns + "/foo")
+	endpointsHandler.ValidateRequestCount(t, 1)
+}
+
 func TestCheckLeftoverEndpoints(t *testing.T) {
 	ns := metav1.NamespaceDefault
 	testServer, _ := makeTestServer(t, ns)