Remove HeadlessService label in endpoints controller before comparing

pkg/controller/endpoint/endpoints_controller.go

@@ -472,9 +472,18 @@ func (e *EndpointController) syncService(key string) error {
 
 	createEndpoints := len(currentEndpoints.ResourceVersion) == 0
 
+	// Compare the sorted subsets and labels
+	// Remove the HeadlessService label from the endpoints if it exists,
+	// as this won't be set on the service itself
+	// and will cause a false negative in this diff check.
+	// But first check if it has that label to avoid expensive copies.
+	compareLabels := currentEndpoints.Labels
+	if _, ok := currentEndpoints.Labels[v1.IsHeadlessService]; ok {
+		compareLabels = utillabels.CloneAndRemoveLabel(currentEndpoints.Labels, v1.IsHeadlessService)
+	}
 	if !createEndpoints &&
 		apiequality.Semantic.DeepEqual(currentEndpoints.Subsets, subsets) &&
-		apiequality.Semantic.DeepEqual(currentEndpoints.Labels, service.Labels) {
+		apiequality.Semantic.DeepEqual(compareLabels, service.Labels) {
 		klog.V(5).Infof("endpoints are equal for %s/%s, skipping update", service.Namespace, service.Name)
 		return nil
 	}

pkg/controller/endpoint/endpoints_controller_test.go

@@ -383,6 +383,33 @@ func TestSyncEndpointsProtocolTCP(t *testing.T) {
 	endpointsHandler.ValidateRequest(t, "/api/v1/namespaces/"+ns+"/endpoints/foo", "PUT", &data)
 }
 
+func TestSyncEndpointsHeadlessServiceLabel(t *testing.T) {
+	ns := metav1.NamespaceDefault
+	testServer, endpointsHandler := makeTestServer(t, ns)
+	defer testServer.Close()
+	endpoints := newController(testServer.URL, 0*time.Second)
+	endpoints.endpointsStore.Add(&v1.Endpoints{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:            "foo",
+			Namespace:       ns,
+			ResourceVersion: "1",
+			Labels: map[string]string{
+				v1.IsHeadlessService: "",
+			},
+		},
+		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 TestSyncEndpointsProtocolUDP(t *testing.T) {
 	ns := "other"
 	testServer, endpointsHandler := makeTestServer(t, ns)