WatchingSecretManager

pkg/kubelet/util/manager/BUILD

@@ -5,6 +5,7 @@ go_library(
     srcs = [
         "cache_based_manager.go",
         "manager.go",
+        "watch_based_manager.go",
     ],
     importpath = "k8s.io/kubernetes/pkg/kubelet/util/manager",
     visibility = ["//visibility:public"],
@@ -13,19 +14,28 @@ go_library(
         "//vendor/k8s.io/api/core/v1: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/fields:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/clock:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/watch:go_default_library",
         "//vendor/k8s.io/apiserver/pkg/storage/etcd:go_default_library",
+        "//vendor/k8s.io/client-go/tools/cache:go_default_library",
     ],
 )
 
 go_test(
     name = "go_default_test",
-    srcs = ["cache_based_manager_test.go"],
+    srcs = [
+        "cache_based_manager_test.go",
+        "watch_based_manager_test.go",
+    ],
     embed = [":go_default_library"],
     deps = [
         "//pkg/api/v1/pod:go_default_library",
+        "//pkg/apis/core/v1:go_default_library",
         "//vendor/github.com/stretchr/testify/assert:go_default_library",
         "//vendor/k8s.io/api/core/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
@@ -33,6 +43,8 @@ go_test(
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/clock:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/watch:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes/fake:go_default_library",
         "//vendor/k8s.io/client-go/testing:go_default_library",

pkg/kubelet/util/manager/watch_based_manager.go

+/*
+Copyright 2018 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.
+*/
+
+// TODO: We did some scalability tests and using watchBasedManager
+// seems to help with apiserver performance at scale visibly.
+// No issues we also observed at the scale of ~200k watchers with a
+// single apiserver.
+// However, we need to perform more extensive testing before we
+// enable this in production setups.
+
+package manager
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"k8s.io/api/core/v1"
+	"k8s.io/client-go/tools/cache"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/apimachinery/pkg/watch"
+)
+
+type listObjectFunc func(string, metav1.ListOptions) (runtime.Object, error)
+type watchObjectFunc func(string, metav1.ListOptions) (watch.Interface, error)
+type newObjectFunc func() runtime.Object
+
+// objectCacheItem is a single item stored in objectCache.
+type objectCacheItem struct {
+	refCount  int
+	store     cache.Store
+	hasSynced func() (bool, error)
+	stopCh    chan struct{}
+}
+
+// objectCache is a local cache of objects propagated via
+// individual watches.
+type objectCache struct {
+	listObject    listObjectFunc
+	watchObject   watchObjectFunc
+	newObject     newObjectFunc
+	groupResource schema.GroupResource
+
+	lock  sync.Mutex
+	items map[objectKey]*objectCacheItem
+}
+
+// NewObjectCache returns a new watch-based instance of Store interface.
+func NewObjectCache(listObject listObjectFunc, watchObject watchObjectFunc, newObject newObjectFunc, groupResource schema.GroupResource) Store {
+	return &objectCache{
+		listObject:    listObject,
+		watchObject:   watchObject,
+		newObject:     newObject,
+		groupResource: groupResource,
+		items:         make(map[objectKey]*objectCacheItem),
+	}
+}
+
+func (c *objectCache) newStore() cache.Store {
+	// TODO: We may consider created a dedicated store keeping just a single
+	// item, instead of using a generic store implementation for this purpose.
+	// However, simple benchmarks show that memory overhead in that case is
+	// decrease from ~600B to ~300B per object. So we are not optimizing it
+	// until we will see a good reason for that.
+	return cache.NewStore(cache.MetaNamespaceKeyFunc)
+}
+
+func (c *objectCache) newReflector(namespace, name string) *objectCacheItem {
+	fieldSelector := fields.Set{"metadata.name": name}.AsSelector().String()
+	listFunc := func(options metav1.ListOptions) (runtime.Object, error) {
+		options.FieldSelector = fieldSelector
+		return c.listObject(namespace, options)
+	}
+	watchFunc := func(options metav1.ListOptions) (watch.Interface, error) {
+		options.FieldSelector = fieldSelector
+		return c.watchObject(namespace, options)
+	}
+	store := c.newStore()
+	reflector := cache.NewNamedReflector(
+		fmt.Sprintf("object-%q/%q", namespace, name),
+		&cache.ListWatch{ListFunc: listFunc, WatchFunc: watchFunc},
+		c.newObject(),
+		store,
+		0,
+	)
+	stopCh := make(chan struct{})
+	go reflector.Run(stopCh)
+	return &objectCacheItem{
+		refCount:  0,
+		store:     store,
+		hasSynced: func() (bool, error) { return reflector.LastSyncResourceVersion() != "", nil },
+		stopCh:    stopCh,
+	}
+}
+
+func (c *objectCache) AddReference(namespace, name string) {
+	key := objectKey{namespace: namespace, name: name}
+
+	// AddReference is called from RegisterPod thus it needs to be efficient.
+	// Thus, it is only increaisng refCount and in case of first registration
+	// of a given object it starts corresponding reflector.
+	// It's responsibility of the first Get operation to wait until the
+	// reflector propagated the store.
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	item, exists := c.items[key]
+	if !exists {
+		item = c.newReflector(namespace, name)
+		c.items[key] = item
+	}
+	item.refCount++
+}
+
+func (c *objectCache) DeleteReference(namespace, name string) {
+	key := objectKey{namespace: namespace, name: name}
+
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	if item, ok := c.items[key]; ok {
+		item.refCount--
+		if item.refCount == 0 {
+			// Stop the underlying reflector.
+			close(item.stopCh)
+			delete(c.items, key)
+		}
+	}
+}
+
+// key returns key of an object with a given name and namespace.
+// This has to be in-sync with cache.MetaNamespaceKeyFunc.
+func (c *objectCache) key(namespace, name string) string {
+	if len(namespace) > 0 {
+		return namespace + "/" + name
+	}
+	return name
+}
+
+func (c *objectCache) Get(namespace, name string) (runtime.Object, error) {
+	key := objectKey{namespace: namespace, name: name}
+
+	c.lock.Lock()
+	item, exists := c.items[key]
+	c.lock.Unlock()
+
+	if !exists {
+		return nil, fmt.Errorf("object %q/%q not registered", namespace, name)
+	}
+	if err := wait.PollImmediate(10*time.Millisecond, time.Second, item.hasSynced); err != nil {
+		return nil, fmt.Errorf("couldn't propagate object cache: %v", err)
+	}
+
+	obj, exists, err := item.store.GetByKey(c.key(namespace, name))
+	if err != nil {
+		return nil, err
+	}
+	if !exists {
+		return nil, apierrors.NewNotFound(c.groupResource, name)
+	}
+	if object, ok := obj.(runtime.Object); ok {
+		return object, nil
+	}
+	return nil, fmt.Errorf("unexpected object type: %v", obj)
+}
+
+// NewWatchBasedManager creates a manager that keeps a cache of all objects
+// necessary for registered pods.
+// It implements the following logic:
+// - whenever a pod is created or updated, we start individual watches for all
+//   referenced objects that aren't referenced from other registered pods
+// - every GetObject() returns a value from local cache propagated via watches
+func NewWatchBasedManager(listObject listObjectFunc, watchObject watchObjectFunc, newObject newObjectFunc, groupResource schema.GroupResource, getReferencedObjects func(*v1.Pod) sets.String) Manager {
+	objectStore := NewObjectCache(listObject, watchObject, newObject, groupResource)
+	return NewCacheBasedManager(objectStore, getReferencedObjects)
+}

pkg/kubelet/util/manager/watch_based_manager_test.go

+/*
+Copyright 2018 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 manager
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"k8s.io/api/core/v1"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/apimachinery/pkg/watch"
+
+	clientset "k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/kubernetes/fake"
+	core "k8s.io/client-go/testing"
+
+	corev1 "k8s.io/kubernetes/pkg/apis/core/v1"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func listSecret(fakeClient clientset.Interface) listObjectFunc {
+	return func(namespace string, opts metav1.ListOptions) (runtime.Object, error) {
+		return fakeClient.CoreV1().Secrets(namespace).List(opts)
+	}
+}
+
+func watchSecret(fakeClient clientset.Interface) watchObjectFunc {
+	return func(namespace string, opts metav1.ListOptions) (watch.Interface, error) {
+		return fakeClient.CoreV1().Secrets(namespace).Watch(opts)
+	}
+}
+
+func newSecretCache(fakeClient clientset.Interface) *objectCache {
+	return &objectCache{
+		listObject:    listSecret(fakeClient),
+		watchObject:   watchSecret(fakeClient),
+		newObject:     func() runtime.Object { return &v1.Secret{} },
+		groupResource: corev1.Resource("secret"),
+		items:         make(map[objectKey]*objectCacheItem),
+	}
+}
+
+func TestSecretCache(t *testing.T) {
+	fakeClient := &fake.Clientset{}
+
+	listReactor := func(a core.Action) (bool, runtime.Object, error) {
+		result := &v1.SecretList{
+			ListMeta: metav1.ListMeta{
+				ResourceVersion: "123",
+			},
+		}
+		return true, result, nil
+	}
+	fakeClient.AddReactor("list", "secrets", listReactor)
+	fakeWatch := watch.NewFake()
+	fakeClient.AddWatchReactor("secrets", core.DefaultWatchReactor(fakeWatch, nil))
+
+	store := newSecretCache(fakeClient)
+
+	store.AddReference("ns", "name")
+	_, err := store.Get("ns", "name")
+	if !apierrors.IsNotFound(err) {
+		t.Errorf("Expected NotFound error, got: %v", err)
+	}
+
+	// Eventually we should be able to read added secret.
+	secret := &v1.Secret{
+		ObjectMeta: metav1.ObjectMeta{Name: "name", Namespace: "ns", ResourceVersion: "125"},
+	}
+	fakeWatch.Add(secret)
+	getFn := func() (bool, error) {
+		object, err := store.Get("ns", "name")
+		if err != nil {
+			if apierrors.IsNotFound(err) {
+				return false, nil
+			}
+			return false, err
+		}
+		secret := object.(*v1.Secret)
+		if secret == nil || secret.Name != "name" || secret.Namespace != "ns" {
+			return false, fmt.Errorf("unexpected secret: %v", secret)
+		}
+		return true, nil
+	}
+	if err := wait.PollImmediate(10*time.Millisecond, time.Second, getFn); err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	// Eventually we should observer secret deletion.
+	fakeWatch.Delete(secret)
+	getFn = func() (bool, error) {
+		_, err := store.Get("ns", "name")
+		if err != nil {
+			if apierrors.IsNotFound(err) {
+				return true, nil
+			}
+			return false, err
+		}
+		return false, nil
+	}
+	if err := wait.PollImmediate(10*time.Millisecond, time.Second, getFn); err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	store.DeleteReference("ns", "name")
+	_, err = store.Get("ns", "name")
+	if err == nil || !strings.Contains(err.Error(), "not registered") {
+		t.Errorf("unexpected error: %v", err)
+	}
+}
+
+func TestSecretCacheMultipleRegistrations(t *testing.T) {
+	fakeClient := &fake.Clientset{}
+
+	listReactor := func(a core.Action) (bool, runtime.Object, error) {
+		result := &v1.SecretList{
+			ListMeta: metav1.ListMeta{
+				ResourceVersion: "123",
+			},
+		}
+		return true, result, nil
+	}
+	fakeClient.AddReactor("list", "secrets", listReactor)
+	fakeWatch := watch.NewFake()
+	fakeClient.AddWatchReactor("secrets", core.DefaultWatchReactor(fakeWatch, nil))
+
+	store := newSecretCache(fakeClient)
+
+	store.AddReference("ns", "name")
+	// This should trigger List and Watch actions eventually.
+	actionsFn := func() (bool, error) {
+		actions := fakeClient.Actions()
+		if len(actions) > 2 {
+			return false, fmt.Errorf("too many actions: %v", actions)
+		}
+		if len(actions) < 2 {
+			return false, nil
+		}
+		if actions[0].GetVerb() != "list" || actions[1].GetVerb() != "watch" {
+			return false, fmt.Errorf("unexpected actions: %v", actions)
+		}
+		return true, nil
+	}
+	if err := wait.PollImmediate(10*time.Millisecond, time.Second, actionsFn); err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	// Next registrations shouldn't trigger any new actions.
+	for i := 0; i < 20; i++ {
+		store.AddReference("ns", "name")
+		store.DeleteReference("ns", "name")
+	}
+	actions := fakeClient.Actions()
+	assert.Equal(t, 2, len(actions), "unexpected actions: %#v", actions)
+
+	// Final delete also doesn't trigger any action.
+	store.DeleteReference("ns", "name")
+	_, err := store.Get("ns", "name")
+	if err == nil || !strings.Contains(err.Error(), "not registered") {
+		t.Errorf("unexpected error: %v", err)
+	}
+	actions = fakeClient.Actions()
+	assert.Equal(t, 2, len(actions), "unexpected actions: %#v", actions)
+}