do not mutate endpoints in the apiserver

the endpoints API handler was using the Canonicalize() method to
reorder the endpoints, however, due to differences with the
endpoint controller RepackSubsets(), the controller was considering
the endpoints different despite they were not, generating unnecessary
updates evert resync period.

pkg/registry/core/endpoint/BUILD

@@ -13,7 +13,6 @@ go_library(
     ],
     importpath = "k8s.io/kubernetes/pkg/registry/core/endpoint",
     deps = [
-        "//pkg/api/endpoints:go_default_library",
         "//pkg/api/legacyscheme:go_default_library",
         "//pkg/apis/core:go_default_library",
         "//pkg/apis/core/validation:go_default_library",

pkg/registry/core/endpoint/strategy.go

@@ -22,7 +22,6 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apiserver/pkg/storage/names"
-	endptspkg "k8s.io/kubernetes/pkg/api/endpoints"
 	"k8s.io/kubernetes/pkg/api/legacyscheme"
 	api "k8s.io/kubernetes/pkg/apis/core"
 	"k8s.io/kubernetes/pkg/apis/core/validation"
@@ -60,8 +59,6 @@ func (endpointsStrategy) Validate(ctx context.Context, obj runtime.Object) field
 
 // Canonicalize normalizes the object after validation.
 func (endpointsStrategy) Canonicalize(obj runtime.Object) {
-	endpoints := obj.(*api.Endpoints)
-	endpoints.Subsets = endptspkg.RepackSubsets(endpoints.Subsets)
 }
 
 // AllowCreateOnUpdate is true for endpoints.

test/integration/BUILD

@@ -50,6 +50,7 @@ filegroup(
         "//test/integration/deployment:all-srcs",
         "//test/integration/disruption:all-srcs",
         "//test/integration/dryrun:all-srcs",
+        "//test/integration/endpoints:all-srcs",
         "//test/integration/endpointslice:all-srcs",
         "//test/integration/etcd:all-srcs",
         "//test/integration/events:all-srcs",

test/integration/endpoints/BUILD

@@ -0,0 +1,35 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_test")
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "endpoints_test.go",
+        "main_test.go",
+    ],
+    tags = ["integration"],
+    deps = [
+        "//pkg/controller/endpoint:go_default_library",
+        "//staging/src/k8s.io/api/core/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/intstr:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
+        "//staging/src/k8s.io/client-go/informers:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
+        "//staging/src/k8s.io/client-go/rest:go_default_library",
+        "//test/integration/framework:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

test/integration/endpoints/endpoints_test.go

@@ -0,0 +1,180 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package endpoints
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/informers"
+	clientset "k8s.io/client-go/kubernetes"
+	restclient "k8s.io/client-go/rest"
+	"k8s.io/kubernetes/pkg/controller/endpoint"
+	"k8s.io/kubernetes/test/integration/framework"
+)
+
+func TestEndpointUpdates(t *testing.T) {
+	masterConfig := framework.NewIntegrationTestMasterConfig()
+	_, server, closeFn := framework.RunAMaster(masterConfig)
+	defer closeFn()
+
+	config := restclient.Config{Host: server.URL}
+	client, err := clientset.NewForConfig(&config)
+	if err != nil {
+		t.Fatalf("Error creating clientset: %v", err)
+	}
+
+	informers := informers.NewSharedInformerFactory(client, 0)
+
+	epController := endpoint.NewEndpointController(
+		informers.Core().V1().Pods(),
+		informers.Core().V1().Services(),
+		informers.Core().V1().Endpoints(),
+		client,
+		0)
+
+	// Start informer and controllers
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+	informers.Start(stopCh)
+	go epController.Run(1, stopCh)
+
+	// Create namespace
+	ns := framework.CreateTestingNamespace("test-endpoints-updates", server, t)
+	defer framework.DeleteTestingNamespace(ns, server, t)
+
+	// Create a pod with labels
+	pod := &v1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "test-pod",
+			Namespace: ns.Name,
+			Labels:    labelMap(),
+		},
+		Spec: v1.PodSpec{
+			NodeName: "fakenode",
+			Containers: []v1.Container{
+				{
+					Name:  "fake-name",
+					Image: "fakeimage",
+				},
+			},
+		},
+	}
+
+	createdPod, err := client.CoreV1().Pods(ns.Name).Create(context.TODO(), pod, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to create pod %s: %v", pod.Name, err)
+	}
+
+	// Set pod IPs
+	createdPod.Status = v1.PodStatus{
+		Phase:  v1.PodRunning,
+		PodIPs: []v1.PodIP{{IP: "1.1.1.1"}, {IP: "2001:db8::"}},
+	}
+	_, err = client.CoreV1().Pods(ns.Name).UpdateStatus(context.TODO(), createdPod, metav1.UpdateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to update status of pod %s: %v", pod.Name, err)
+	}
+
+	// Create a service associated to the pod
+	svc := newService(ns.Name, "foo1")
+	svc1, err := client.CoreV1().Services(ns.Name).Create(context.TODO(), svc, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to create service %s: %v", svc.Name, err)
+	}
+
+	// Obtain ResourceVersion of the new endpoint created
+	var resVersion string
+	if err := wait.PollImmediate(1*time.Second, wait.ForeverTestTimeout, func() (bool, error) {
+		endpoints, err := client.CoreV1().Endpoints(ns.Name).Get(context.TODO(), svc.Name, metav1.GetOptions{})
+		if err != nil {
+			t.Logf("error fetching endpoints: %v", err)
+			return false, nil
+		}
+		resVersion = endpoints.ObjectMeta.ResourceVersion
+		return true, nil
+	}); err != nil {
+		t.Fatalf("endpoints not found: %v", err)
+	}
+
+	// Force recomputation on the endpoint controller
+	svc1.SetAnnotations(map[string]string{"foo": "bar"})
+	_, err = client.CoreV1().Services(ns.Name).Update(context.TODO(), svc1, metav1.UpdateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to update service %s: %v", svc1.Name, err)
+	}
+
+	// Create a new service and wait until it has been processed,
+	// this way we can be sure that the endpoint for the original service
+	// was recomputed before asserting, since we only have 1 worker
+	// in the endpoint controller
+	svc2 := newService(ns.Name, "foo2")
+	_, err = client.CoreV1().Services(ns.Name).Create(context.TODO(), svc2, metav1.CreateOptions{})
+	if err != nil {
+		t.Fatalf("Failed to create service %s: %v", svc.Name, err)
+	}
+
+	if err := wait.PollImmediate(1*time.Second, wait.ForeverTestTimeout, func() (bool, error) {
+		_, err := client.CoreV1().Endpoints(ns.Name).Get(context.TODO(), svc2.Name, metav1.GetOptions{})
+		if err != nil {
+			t.Logf("error fetching endpoints: %v", err)
+			return false, nil
+		}
+		return true, nil
+	}); err != nil {
+		t.Fatalf("endpoints not found: %v", err)
+	}
+
+	// the endpoint controller should not update the endpoint created for the original
+	// service since nothing has changed, the resource version has to be the same
+	endpoints, err := client.CoreV1().Endpoints(ns.Name).Get(context.TODO(), svc.Name, metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("error fetching endpoints: %v", err)
+	}
+	if resVersion != endpoints.ObjectMeta.ResourceVersion {
+		t.Fatalf("endpoints resource version does not match, expected %s received %s", resVersion, endpoints.ObjectMeta.ResourceVersion)
+	}
+
+}
+
+func labelMap() map[string]string {
+	return map[string]string{"foo": "bar"}
+}
+
+// newService returns a service with selector and exposing ports
+func newService(namespace, name string) *v1.Service {
+	return &v1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      name,
+			Namespace: namespace,
+			Labels:    labelMap(),
+		},
+		Spec: v1.ServiceSpec{
+			Selector: labelMap(),
+			Ports: []v1.ServicePort{
+				{Name: "port-1338", Port: 1338, Protocol: "TCP", TargetPort: intstr.FromInt(1338)},
+				{Name: "port-1337", Port: 1337, Protocol: "TCP", TargetPort: intstr.FromInt(1337)},
+			},
+		},
+	}
+
+}

test/integration/endpoints/main_test.go

@@ -0,0 +1,27 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package endpoints
+
+import (
+	"testing"
+
+	"k8s.io/kubernetes/test/integration/framework"
+)
+
+func TestMain(m *testing.M) {
+	framework.EtcdMain(m.Run)
+}