Option to restrict informer cache to a namespace

A namespace option can be passed from the manager to
the cache which restricts the ListWatch for all informers
to the desired namespace. This way a manager can be run
with a Role instead of a ClusterRole.

Author: hasbro17

pkg/cache/cache.go

@@ -79,6 +79,10 @@ type Options struct {
 
 	// Resync is the resync period. Defaults to defaultResyncTime.
 	Resync *time.Duration
+
+	// Namespace restricts the cache's ListWatch to the desired namespace
+	// Default watches all namespaces
+	Namespace string
 }
 
 var defaultResyncTime = 10 * time.Hour
@@ -89,7 +93,7 @@ func New(config *rest.Config, opts Options) (Cache, error) {
 	if err != nil {
 		return nil, err
 	}
-	im := internal.NewInformersMap(config, opts.Scheme, opts.Mapper, *opts.Resync)
+	im := internal.NewInformersMap(config, opts.Scheme, opts.Mapper, *opts.Resync, opts.Namespace)
 	return &informerCache{InformersMap: im}, nil
 }
 

pkg/cache/cache_test.go

@@ -195,6 +195,28 @@ var _ = Describe("Informer Cache", func() {
 				Expect(actual.Namespace).To(Equal(testNamespaceOne))
 			})
 
+			It("should be able to restrict cache to a namespace", func() {
+				By("creating a namespaced cache")
+				namespacedCache, err := cache.New(cfg, cache.Options{Namespace: testNamespaceOne})
+				Expect(err).NotTo(HaveOccurred())
+
+				By("running the cache and waiting for it to sync")
+				go func() {
+					defer GinkgoRecover()
+					Expect(namespacedCache.Start(stop)).To(Succeed())
+				}()
+				Expect(namespacedCache.WaitForCacheSync(stop)).NotTo(BeFalse())
+
+				By("listing pods in all namespaces")
+				out := &kcorev1.PodList{}
+				Expect(namespacedCache.List(context.Background(), nil, out)).To(Succeed())
+
+				By("verifying the returned pod is from the watched namespace")
+				Expect(out.Items).NotTo(BeEmpty())
+				Expect(out.Items).Should(HaveLen(1))
+				Expect(out.Items[0].Namespace).To(Equal(testNamespaceOne))
+			})
+
 			It("should deep copy the object unless told otherwise", func() {
 				By("retrieving a specific pod from the cache")
 				out := &kcorev1.Pod{}
@@ -333,6 +355,33 @@ var _ = Describe("Informer Cache", func() {
 				Expect(actual.GetNamespace()).To(Equal(testNamespaceOne))
 			})
 
+			It("should be able to restrict cache to a namespace", func() {
+				By("creating a namespaced cache")
+				namespacedCache, err := cache.New(cfg, cache.Options{Namespace: testNamespaceOne})
+				Expect(err).NotTo(HaveOccurred())
+
+				By("running the cache and waiting for it to sync")
+				go func() {
+					defer GinkgoRecover()
+					Expect(namespacedCache.Start(stop)).To(Succeed())
+				}()
+				Expect(namespacedCache.WaitForCacheSync(stop)).NotTo(BeFalse())
+
+				By("listing pods in all namespaces")
+				out := &unstructured.UnstructuredList{}
+				out.SetGroupVersionKind(schema.GroupVersionKind{
+					Group:   "",
+					Version: "v1",
+					Kind:    "PodList",
+				})
+				Expect(namespacedCache.List(context.Background(), nil, out)).To(Succeed())
+
+				By("verifying the returned pod is from the watched namespace")
+				Expect(out.Items).NotTo(BeEmpty())
+				Expect(out.Items).Should(HaveLen(1))
+				Expect(out.Items[0].GetNamespace()).To(Equal(testNamespaceOne))
+			})
+
 			It("should deep copy the object unless told otherwise", func() {
 				By("retrieving a specific pod from the cache")
 				out := &unstructured.Unstructured{}

pkg/cache/internal/deleg_map.go

@@ -44,11 +44,12 @@ type InformersMap struct {
 func NewInformersMap(config *rest.Config,
 	scheme *runtime.Scheme,
 	mapper meta.RESTMapper,
-	resync time.Duration) *InformersMap {
+	resync time.Duration,
+	namespace string) *InformersMap {
 
 	return &InformersMap{
-		structured:   newStructuredInformersMap(config, scheme, mapper, resync),
-		unstructured: newUnstructuredInformersMap(config, scheme, mapper, resync),
+		structured:   newStructuredInformersMap(config, scheme, mapper, resync, namespace),
+		unstructured: newUnstructuredInformersMap(config, scheme, mapper, resync, namespace),
 
 		Scheme: scheme,
 	}
@@ -85,11 +86,11 @@ func (m *InformersMap) Get(gvk schema.GroupVersionKind, obj runtime.Object) (*Ma
 }
 
 // newStructuredInformersMap creates a new InformersMap for structured objects.
-func newStructuredInformersMap(config *rest.Config, scheme *runtime.Scheme, mapper meta.RESTMapper, resync time.Duration) *specificInformersMap {
-	return newSpecificInformersMap(config, scheme, mapper, resync, createStructuredListWatch)
+func newStructuredInformersMap(config *rest.Config, scheme *runtime.Scheme, mapper meta.RESTMapper, resync time.Duration, namespace string) *specificInformersMap {
+	return newSpecificInformersMap(config, scheme, mapper, resync, namespace, createStructuredListWatch)
 }
 
 // newUnstructuredInformersMap creates a new InformersMap for unstructured objects.
-func newUnstructuredInformersMap(config *rest.Config, scheme *runtime.Scheme, mapper meta.RESTMapper, resync time.Duration) *specificInformersMap {
-	return newSpecificInformersMap(config, scheme, mapper, resync, createUnstructuredListWatch)
+func newUnstructuredInformersMap(config *rest.Config, scheme *runtime.Scheme, mapper meta.RESTMapper, resync time.Duration, namespace string) *specificInformersMap {
+	return newSpecificInformersMap(config, scheme, mapper, resync, namespace, createUnstructuredListWatch)
 }

pkg/cache/internal/informers_map.go

@@ -42,7 +42,9 @@ type createListWatcherFunc func(gvk schema.GroupVersionKind, ip *specificInforme
 func newSpecificInformersMap(config *rest.Config,
 	scheme *runtime.Scheme,
 	mapper meta.RESTMapper,
-	resync time.Duration, createListWatcher createListWatcherFunc) *specificInformersMap {
+	resync time.Duration,
+	namespace string,
+	createListWatcher createListWatcherFunc) *specificInformersMap {
 	ip := &specificInformersMap{
 		config:            config,
 		Scheme:            scheme,
@@ -52,6 +54,7 @@ func newSpecificInformersMap(config *rest.Config,
 		paramCodec:        runtime.NewParameterCodec(scheme),
 		resync:            resync,
 		createListWatcher: createListWatcher,
+		namespace:         namespace,
 	}
 	return ip
 }
@@ -102,6 +105,10 @@ type specificInformersMap struct {
 	// and allows for abstracting over the particulars of structured vs
 	// unstructured objects.
 	createListWatcher createListWatcherFunc
+
+	// namespace is the namespace that all ListWatches are restricted to
+	// default or empty string means all namespaces
+	namespace string
 }
 
 // Start calls Run on each of the informers and sets started to true.  Blocks on the stop channel.
@@ -225,14 +232,14 @@ func createStructuredListWatch(gvk schema.GroupVersionKind, ip *specificInformer
 	return &cache.ListWatch{
 		ListFunc: func(opts metav1.ListOptions) (runtime.Object, error) {
 			res := listObj.DeepCopyObject()
-			err := client.Get().Resource(mapping.Resource.Resource).VersionedParams(&opts, ip.paramCodec).Do().Into(res)
+			err := client.Get().NamespaceIfScoped(ip.namespace, ip.namespace != "").Resource(mapping.Resource.Resource).VersionedParams(&opts, ip.paramCodec).Do().Into(res)
 			return res, err
 		},
 		// Setup the watch function
 		WatchFunc: func(opts metav1.ListOptions) (watch.Interface, error) {
 			// Watch needs to be set to true separately
 			opts.Watch = true
-			return client.Get().Resource(mapping.Resource.Resource).VersionedParams(&opts, ip.paramCodec).Watch()
+			return client.Get().NamespaceIfScoped(ip.namespace, ip.namespace != "").Resource(mapping.Resource.Resource).VersionedParams(&opts, ip.paramCodec).Watch()
 		},
 	}, nil
 }
@@ -252,12 +259,18 @@ func createUnstructuredListWatch(gvk schema.GroupVersionKind, ip *specificInform
 	// Create a new ListWatch for the obj
 	return &cache.ListWatch{
 		ListFunc: func(opts metav1.ListOptions) (runtime.Object, error) {
+			if ip.namespace != "" {
+				return dynamicClient.Resource(mapping.Resource).Namespace(ip.namespace).List(opts)
+			}
 			return dynamicClient.Resource(mapping.Resource).List(opts)
 		},
 		// Setup the watch function
 		WatchFunc: func(opts metav1.ListOptions) (watch.Interface, error) {
 			// Watch needs to be set to true separately
 			opts.Watch = true
+			if ip.namespace != "" {
+				return dynamicClient.Resource(mapping.Resource).Namespace(ip.namespace).Watch(opts)
+			}
 			return dynamicClient.Resource(mapping.Resource).Watch(opts)
 		},
 	}, nil

pkg/manager/manager.go

@@ -106,6 +106,10 @@ type Options struct {
 	// will use for holding the leader lock.
 	LeaderElectionID string
 
+	// Namespace if specified restricts the manager's cache to watch the desired namespace
+	// Defaults to all namespaces
+	Namespace string
+
 	// Dependency injection for testing
 	newCache            func(config *rest.Config, opts cache.Options) (cache.Cache, error)
 	newClient           func(config *rest.Config, options client.Options) (client.Client, error)
@@ -153,7 +157,7 @@ func New(config *rest.Config, options Options) (Manager, error) {
 	}
 
 	// Create the cache for the cached read client and registering informers
-	cache, err := options.newCache(config, cache.Options{Scheme: options.Scheme, Mapper: mapper, Resync: options.SyncPeriod})
+	cache, err := options.newCache(config, cache.Options{Scheme: options.Scheme, Mapper: mapper, Resync: options.SyncPeriod, Namespace: options.Namespace})
 	if err != nil {
 		return nil, err
 	}