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store.go
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store.go
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// Copyright 2017 Istio 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 crd provides the store interface to config resources stored as
// kubernetes custom resource definitions (CRDs).
package crd
import (
"context"
"sync"
"time"
"github.com/golang/glog"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
"k8s.io/client-go/discovery"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/cache"
"istio.io/istio/mixer/pkg/config/store"
)
const (
// API group / version for istio config.
apiGroup = "config.istio.io"
apiVersion = "v1alpha2"
apiGroupVersion = apiGroup + "/" + apiVersion
)
const (
// initWaiterInterval is the interval to check if the initial data is ready
// in the cache.
initWaiterInterval = time.Millisecond
// crdRetryTimeout is the default timeout duration to retry initialization
// of the caches when some CRDs are missing. The timeout can be customized
// through "retry-timeout" query parameter in the config URL,
// like k8s://?retry-timeout=1m
crdRetryTimeout = time.Second * 30
)
// The interval to wait between the attempt to initialize caches. This is not const
// to allow changing the value for unittests.
var retryInterval = time.Second / 2
type listerWatcherBuilderInterface interface {
build(res metav1.APIResource) cache.ListerWatcher
}
func waitForSynced(ctx context.Context, informers map[string]cache.SharedInformer) <-chan struct{} {
out := make(chan struct{})
go func() {
tick := time.NewTicker(initWaiterInterval)
loop:
for len(informers) > 0 {
select {
case <-ctx.Done():
break loop
case <-tick.C:
for k, i := range informers {
if i.HasSynced() {
delete(informers, k)
}
}
}
}
tick.Stop()
close(out)
}()
return out
}
// Store offers store.Store2Backend interface through kubernetes custom resource definitions.
type Store struct {
conf *rest.Config
ns map[string]bool
retryTimeout time.Duration
cacheMutex sync.Mutex
caches map[string]cache.Store
watchMutex sync.RWMutex
watchCtx context.Context
watchCh chan store.BackendEvent
// They are used to inject testing interfaces.
discoveryBuilder func(conf *rest.Config) (discovery.DiscoveryInterface, error)
listerWatcherBuilder func(conf *rest.Config) (listerWatcherBuilderInterface, error)
}
var _ store.Store2Backend = &Store{}
// checkAndCreateCaches checks the presence of custom resource definitions through the discovery API,
// and then create caches through lwBUilder which is in kinds. It retries within the timeout duration.
// If the timeout duration is 0, it waits forever (which should be done within a goroutine).
// Returns the created shared informers, and the list of kinds which are not created yet.
func (s *Store) checkAndCreateCaches(
ctx context.Context,
timeout time.Duration,
d discovery.DiscoveryInterface,
lwBuilder listerWatcherBuilderInterface,
kinds []string) (informers map[string]cache.SharedInformer, remaining []string) {
kindsSet := map[string]bool{}
for _, k := range kinds {
kindsSet[k] = true
}
informers = map[string]cache.SharedInformer{}
retry := false
retryCtx := ctx
if timeout > 0 {
var cancel context.CancelFunc
retryCtx, cancel = context.WithTimeout(ctx, timeout)
defer cancel()
}
for added := 0; added < len(kinds); {
if retryCtx.Err() != nil {
break
}
if retry {
glog.V(4).Infof("Retrying to fetch config...")
time.Sleep(retryInterval)
}
resources, err := d.ServerResourcesForGroupVersion(apiGroupVersion)
if err != nil {
glog.V(3).Infof("Failed to obtain resources for CRD: %v", err)
continue
}
s.cacheMutex.Lock()
for _, res := range resources.APIResources {
if _, ok := s.caches[res.Kind]; ok {
continue
}
if _, ok := kindsSet[res.Kind]; ok {
cl := lwBuilder.build(res)
informer := cache.NewSharedInformer(cl, &unstructured.Unstructured{}, 0)
s.caches[res.Kind] = informer.GetStore()
informers[res.Kind] = informer
delete(kindsSet, res.Kind)
informer.AddEventHandler(s)
go informer.Run(ctx.Done())
added++
}
}
s.cacheMutex.Unlock()
retry = true
}
remaining = make([]string, 0, len(kindsSet))
for k := range kindsSet {
remaining = append(remaining, k)
}
return informers, remaining
}
// Init implements store.Store2Backend interface.
func (s *Store) Init(ctx context.Context, kinds []string) error {
d, err := s.discoveryBuilder(s.conf)
if err != nil {
return err
}
lwBuilder, err := s.listerWatcherBuilder(s.conf)
if err != nil {
return err
}
s.caches = make(map[string]cache.Store, len(kinds))
informers, remainingKinds := s.checkAndCreateCaches(ctx, s.retryTimeout, d, lwBuilder, kinds)
if len(remainingKinds) > 0 {
// Wait asynchronously for other kinds.
go s.checkAndCreateCaches(ctx, 0, d, lwBuilder, remainingKinds)
}
<-waitForSynced(ctx, informers)
return nil
}
// Watch implements store.Store2Backend interface.
func (s *Store) Watch(ctx context.Context) (<-chan store.BackendEvent, error) {
ch := make(chan store.BackendEvent)
s.watchMutex.Lock()
s.watchCtx = ctx
s.watchCh = ch
s.watchMutex.Unlock()
return ch, nil
}
// Get implements store.Store2Backend interface.
func (s *Store) Get(key store.Key) (*store.BackEndResource, error) {
if s.ns != nil && !s.ns[key.Namespace] {
return nil, store.ErrNotFound
}
s.cacheMutex.Lock()
c, ok := s.caches[key.Kind]
s.cacheMutex.Unlock()
if !ok {
return nil, store.ErrNotFound
}
req := &unstructured.Unstructured{}
req.SetName(key.Name)
req.SetNamespace(key.Namespace)
obj, exists, err := c.Get(req)
if err != nil {
return nil, err
}
if !exists {
return nil, store.ErrNotFound
}
uns, _ := obj.(*unstructured.Unstructured)
return backEndResource(uns), nil
}
func backEndResource(uns *unstructured.Unstructured) *store.BackEndResource {
spec, _ := uns.UnstructuredContent()["spec"].(map[string]interface{})
return &store.BackEndResource{
Metadata: store.ResourceMeta{
Name: uns.GetName(),
Namespace: uns.GetNamespace(),
Labels: uns.GetLabels(),
Annotations: uns.GetAnnotations(),
Revision: uns.GetResourceVersion(),
},
Spec: spec,
}
}
// List implements store.Store2Backend interface.
func (s *Store) List() map[store.Key]*store.BackEndResource {
result := make(map[store.Key]*store.BackEndResource)
s.cacheMutex.Lock()
for kind, c := range s.caches {
for _, obj := range c.List() {
uns := obj.(*unstructured.Unstructured)
key := store.Key{Kind: kind, Name: uns.GetName(), Namespace: uns.GetNamespace()}
if s.ns != nil && !s.ns[key.Namespace] {
continue
}
result[key] = backEndResource(uns)
}
}
s.cacheMutex.Unlock()
return result
}
func toEvent(t store.ChangeType, obj interface{}) store.BackendEvent {
uns := obj.(*unstructured.Unstructured)
key := store.Key{Kind: uns.GetKind(), Namespace: uns.GetNamespace(), Name: uns.GetName()}
return store.BackendEvent{
Type: t,
Key: key,
Value: backEndResource(uns),
}
}
func (s *Store) dispatch(ev store.BackendEvent) {
s.watchMutex.RLock()
defer s.watchMutex.RUnlock()
if s.watchCtx == nil {
return
}
select {
case <-s.watchCtx.Done():
case s.watchCh <- ev:
}
}
// OnAdd implements cache.ResourceEventHandler interface.
func (s *Store) OnAdd(obj interface{}) {
ev := toEvent(store.Update, obj)
if s.ns == nil || s.ns[ev.Key.Namespace] {
s.dispatch(ev)
}
}
// OnUpdate implements cache.ResourceEventHandler interface.
func (s *Store) OnUpdate(oldObj, newObj interface{}) {
ev := toEvent(store.Update, newObj)
if s.ns == nil || s.ns[ev.Key.Namespace] {
s.dispatch(ev)
}
}
// OnDelete implements cache.ResourceEventHandler interface.
func (s *Store) OnDelete(obj interface{}) {
ev := toEvent(store.Delete, obj)
ev.Value = nil
if s.ns == nil || s.ns[ev.Key.Namespace] {
s.dispatch(ev)
}
}