plugin/kubernetes: add namespace watch (#1533)

* add namespace watch

* start ns watch, and add sync check

plugin/kubernetes/controller.go

@@ -60,10 +60,12 @@ type dnsControl struct {
 	svcController cache.Controller
 	podController cache.Controller
 	epController  cache.Controller
+	nsController  cache.Controller
 
 	svcLister cache.Indexer
 	podLister cache.Indexer
 	epLister  cache.Indexer
+	nsLister  storeToNamespaceLister
 
 	// stopLock is used to enforce only a single call to Stop is active.
 	// Needed because we allow stopping through an http endpoint and
@@ -88,6 +90,7 @@ func newdnsController(kubeClient *kubernetes.Clientset, opts dnsControlOpts) *dn
 		selector: opts.selector,
 		stopCh:   make(chan struct{}),
 	}
+
 	dns.svcLister, dns.svcController = cache.NewIndexerInformer(
 		&cache.ListWatch{
 			ListFunc:  serviceListFunc(dns.client, namespace, dns.selector),
@@ -109,6 +112,7 @@ func newdnsController(kubeClient *kubernetes.Clientset, opts dnsControlOpts) *dn
 			cache.ResourceEventHandlerFuncs{AddFunc: dns.Add, UpdateFunc: dns.Update, DeleteFunc: dns.Delete},
 			cache.Indexers{podIPIndex: podIPIndexFunc})
 	}
+
 	dns.epLister, dns.epController = cache.NewIndexerInformer(
 		&cache.ListWatch{
 			ListFunc:  endpointsListFunc(dns.client, namespace, dns.selector),
@@ -119,9 +123,21 @@ func newdnsController(kubeClient *kubernetes.Clientset, opts dnsControlOpts) *dn
 		cache.ResourceEventHandlerFuncs{AddFunc: dns.Add, UpdateFunc: dns.Update, DeleteFunc: dns.Delete},
 		cache.Indexers{epNameNamespaceIndex: epNameNamespaceIndexFunc, epIPIndex: epIPIndexFunc})
 
+	dns.nsLister.Store, dns.nsController = cache.NewInformer(
+		&cache.ListWatch{
+			ListFunc:  namespaceListFunc(dns.client, dns.selector),
+			WatchFunc: namespaceWatchFunc(dns.client, dns.selector),
+		},
+		&api.Namespace{}, opts.resyncPeriod, cache.ResourceEventHandlerFuncs{})
+
 	return &dns
 }
 
+// storeToNamespaceLister makes a Store that lists Namespaces.
+type storeToNamespaceLister struct {
+	cache.Store
+}
+
 func podIPIndexFunc(obj interface{}) ([]string, error) {
 	p, ok := obj.(*api.Pod)
 	if !ok {
@@ -246,6 +262,32 @@ func endpointsWatchFunc(c *kubernetes.Clientset, ns string, s labels.Selector) f
 	}
 }
 
+func namespaceListFunc(c *kubernetes.Clientset, s labels.Selector) func(meta.ListOptions) (runtime.Object, error) {
+	return func(opts meta.ListOptions) (runtime.Object, error) {
+		if s != nil {
+			opts.LabelSelector = s.String()
+		}
+		listV1, err := c.CoreV1().Namespaces().List(opts)
+		if err != nil {
+			return nil, err
+		}
+		return listV1, err
+	}
+}
+
+func namespaceWatchFunc(c *kubernetes.Clientset, s labels.Selector) func(options meta.ListOptions) (watch.Interface, error) {
+	return func(options meta.ListOptions) (watch.Interface, error) {
+		if s != nil {
+			options.LabelSelector = s.String()
+		}
+		w, err := c.CoreV1().Namespaces().Watch(options)
+		if err != nil {
+			return nil, err
+		}
+		return w, nil
+	}
+}
+
 // Stop stops the  controller.
 func (dns *dnsControl) Stop() error {
 	dns.stopLock.Lock()
@@ -269,6 +311,7 @@ func (dns *dnsControl) Run() {
 	if dns.podController != nil {
 		go dns.podController.Run(dns.stopCh)
 	}
+	go dns.nsController.Run(dns.stopCh)
 	<-dns.stopCh
 }
 
@@ -280,7 +323,8 @@ func (dns *dnsControl) HasSynced() bool {
 	if dns.podController != nil {
 		c = dns.podController.HasSynced()
 	}
-	return a && b && c
+	d := dns.nsController.HasSynced()
+	return a && b && c && d
 }
 
 func (dns *dnsControl) ServiceList() (svcs []*api.Service) {
@@ -410,14 +454,19 @@ func (dns *dnsControl) GetNodeByName(name string) (*api.Node, error) {
 }
 
 // GetNamespaceByName returns the namespace by name. If nothing is found an
-// error is returned. This query causes a roundtrip to the k8s API server, so
-// use sparingly.
+// error is returned.
 func (dns *dnsControl) GetNamespaceByName(name string) (*api.Namespace, error) {
-	v1ns, err := dns.client.CoreV1().Namespaces().Get(name, meta.GetOptions{})
-	if err != nil {
-		return &api.Namespace{}, err
+	os := dns.nsLister.List()
+	for _, o := range os {
+		ns, ok := o.(*api.Namespace)
+		if !ok {
+			continue
+		}
+		if name == ns.ObjectMeta.Name {
+			return ns, nil
+		}
 	}
-	return v1ns, nil
+	return nil, fmt.Errorf("namespace not found")
 }
 
 func (dns *dnsControl) Modified() int64 {