kubernetes: Improve namespace usage (#4767)

* Use GetByKey instead of List in GetNamespaceByName.
* Add ToNamespace to reduce memory for namespace cache.
Signed-off-by: Mat Lowery <mlowery@ebay.com>

plugin/k8s_external/external_test.go

@@ -12,7 +12,6 @@ import (
 
 	"github.com/miekg/dns"
 	api "k8s.io/api/core/v1"
-	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
 func TestExternal(t *testing.T) {
@@ -176,11 +175,9 @@ func (external) GetNodeByName(ctx context.Context, name string) (*api.Node, erro
 func (external) SvcIndex(s string) []*object.Service                               { return svcIndexExternal[s] }
 func (external) PodIndex(string) []*object.Pod                                     { return nil }
 
-func (external) GetNamespaceByName(name string) (*api.Namespace, error) {
-	return &api.Namespace{
-		ObjectMeta: meta.ObjectMeta{
-			Name: name,
-		},
+func (external) GetNamespaceByName(name string) (*object.Namespace, error) {
+	return &object.Namespace{
+		Name: name,
 	}, nil
 }
 

plugin/kubernetes/controller.go

@@ -39,7 +39,7 @@ type dnsController interface {
 	EpIndexReverse(string) []*object.Endpoints
 
 	GetNodeByName(context.Context, string) (*api.Node, error)
-	GetNamespaceByName(string) (*api.Namespace, error)
+	GetNamespaceByName(string) (*object.Namespace, error)
 
 	Run()
 	HasSynced() bool
@@ -150,14 +150,16 @@ func newdnsController(ctx context.Context, kubeClient kubernetes.Interface, opts
 		dns.epLock.Unlock()
 	}
 
-	dns.nsLister, dns.nsController = cache.NewInformer(
+	dns.nsLister, dns.nsController = object.NewIndexerInformer(
 		&cache.ListWatch{
 			ListFunc:  namespaceListFunc(ctx, dns.client, dns.namespaceSelector),
 			WatchFunc: namespaceWatchFunc(ctx, dns.client, dns.namespaceSelector),
 		},
 		&api.Namespace{},
-		defaultResyncPeriod,
-		cache.ResourceEventHandlerFuncs{})
+		cache.ResourceEventHandlerFuncs{},
+		cache.Indexers{},
+		object.DefaultProcessor(object.ToNamespace, nil),
+	)
 
 	return &dns
 }
@@ -539,18 +541,19 @@ func (dns *dnsControl) GetNodeByName(ctx context.Context, name string) (*api.Nod
 }
 
 // GetNamespaceByName returns the namespace by name. If nothing is found an error is returned.
-func (dns *dnsControl) GetNamespaceByName(name string) (*api.Namespace, error) {
-	os := dns.nsLister.List()
-	for _, o := range os {
-		ns, ok := o.(*api.Namespace)
-		if !ok {
-			continue
-		}
-		if name == ns.ObjectMeta.Name {
-			return ns, nil
-		}
+func (dns *dnsControl) GetNamespaceByName(name string) (*object.Namespace, error) {
+	o, exists, err := dns.nsLister.GetByKey(name)
+	if err != nil {
+		return nil, err
+	}
+	if !exists {
+		return nil, fmt.Errorf("namespace not found")
+	}
+	ns, ok := o.(*object.Namespace)
+	if !ok {
+		return nil, fmt.Errorf("found key but not namespace")
 	}
-	return nil, fmt.Errorf("namespace not found")
+	return ns, nil
 }
 
 func (dns *dnsControl) Add(obj interface{})               { dns.updateModified() }

plugin/kubernetes/external_test.go

@@ -11,7 +11,6 @@ import (
 
 	"github.com/miekg/dns"
 	api "k8s.io/api/core/v1"
-	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
 var extCases = []struct {
@@ -91,11 +90,9 @@ func (external) GetNodeByName(ctx context.Context, name string) (*api.Node, erro
 func (external) SvcIndex(s string) []*object.Service                               { return svcIndexExternal[s] }
 func (external) PodIndex(string) []*object.Pod                                     { return nil }
 
-func (external) GetNamespaceByName(name string) (*api.Namespace, error) {
-	return &api.Namespace{
-		ObjectMeta: meta.ObjectMeta{
-			Name: name,
-		},
+func (external) GetNamespaceByName(name string) (*object.Namespace, error) {
+	return &object.Namespace{
+		Name: name,
 	}, nil
 }
 

plugin/kubernetes/handler_test.go

@@ -782,16 +782,14 @@ func (APIConnServeTest) GetNodeByName(ctx context.Context, name string) (*api.No
 	}, nil
 }
 
-func (APIConnServeTest) GetNamespaceByName(name string) (*api.Namespace, error) {
+func (APIConnServeTest) GetNamespaceByName(name string) (*object.Namespace, error) {
 	if name == "pod-nons" { // handler_pod_verified_test.go uses this for non-existent namespace.
-		return &api.Namespace{}, nil
+		return nil, fmt.Errorf("namespace not found")
 	}
 	if name == "nsnoexist" {
 		return nil, fmt.Errorf("namespace not found")
 	}
-	return &api.Namespace{
-		ObjectMeta: meta.ObjectMeta{
-			Name: name,
-		},
+	return &object.Namespace{
+		Name: name,
 	}, nil
 }

plugin/kubernetes/kubernetes_test.go

@@ -253,11 +253,9 @@ func (APIConnServiceTest) GetNodeByName(ctx context.Context, name string) (*api.
 	}, nil
 }
 
-func (APIConnServiceTest) GetNamespaceByName(name string) (*api.Namespace, error) {
-	return &api.Namespace{
-		ObjectMeta: meta.ObjectMeta{
-			Name: name,
-		},
+func (APIConnServiceTest) GetNamespaceByName(name string) (*object.Namespace, error) {
+	return &object.Namespace{
+		Name: name,
 	}, nil
 }
 

plugin/kubernetes/namespace.go

@@ -5,11 +5,11 @@ package kubernetes
 // Returns true even for namespaces not exposed by plugin configuration,
 // see namespaceExposed.
 func (k *Kubernetes) filteredNamespaceExists(namespace string) bool {
-	ns, err := k.APIConn.GetNamespaceByName(namespace)
+	_, err := k.APIConn.GetNamespaceByName(namespace)
 	if err != nil {
 		return false
 	}
-	return ns.ObjectMeta.Name == namespace
+	return true
 }
 
 // configuredNamespace returns true when the namespace is exposed through the plugin

plugin/kubernetes/ns_test.go

@@ -2,6 +2,7 @@ package kubernetes
 
 import (
 	"context"
+	"fmt"
 	"net"
 	"testing"
 
@@ -91,8 +92,8 @@ func (APIConnTest) EpIndexReverse(ip string) []*object.Endpoints {
 func (APIConnTest) GetNodeByName(ctx context.Context, name string) (*api.Node, error) {
 	return &api.Node{}, nil
 }
-func (APIConnTest) GetNamespaceByName(name string) (*api.Namespace, error) {
-	return &api.Namespace{}, nil
+func (APIConnTest) GetNamespaceByName(name string) (*object.Namespace, error) {
+	return nil, fmt.Errorf("namespace not found")
 }
 
 func TestNsAddrs(t *testing.T) {

plugin/kubernetes/object/namespace.go

+package object
+
+import (
+	"fmt"
+
+	api "k8s.io/api/core/v1"
+	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+// Namespace is a stripped down api.Namespace with only the items we need for CoreDNS.
+type Namespace struct {
+	// Don't add new fields to this struct without talking to the CoreDNS maintainers.
+	Version   string
+	Name      string
+
+	*Empty
+}
+
+// ToNamespace returns a function that converts an api.Namespace to a *Namespace.
+func ToNamespace(obj meta.Object) (meta.Object, error) {
+	ns, ok := obj.(*api.Namespace)
+	if !ok {
+		return nil, fmt.Errorf("unexpected object %v", obj)
+	}
+	n := &Namespace{
+		Version: ns.GetResourceVersion(),
+		Name:    ns.GetName(),
+	}
+	*ns = api.Namespace{}
+	return n, nil
+}
+
+var _ runtime.Object = &Namespace{}
+
+// DeepCopyObject implements the ObjectKind interface.
+func (n *Namespace) DeepCopyObject() runtime.Object {
+	n1 := &Namespace{
+		Version: n.Version,
+		Name:    n.Name,
+	}
+	return n1
+}
+
+// GetNamespace implements the metav1.Object interface.
+func (n *Namespace) GetNamespace() string { return "" }
+
+// SetNamespace implements the metav1.Object interface.
+func (n *Namespace) SetNamespace(namespace string) {}
+
+// GetName implements the metav1.Object interface.
+func (n *Namespace) GetName() string { return n.Name }
+
+// SetName implements the metav1.Object interface.
+func (n *Namespace) SetName(name string) {}
+
+// GetResourceVersion implements the metav1.Object interface.
+func (n *Namespace) GetResourceVersion() string { return n.Version }
+
+// SetResourceVersion implements the metav1.Object interface.
+func (n *Namespace) SetResourceVersion(version string) {}

plugin/kubernetes/reverse_test.go

@@ -142,11 +142,9 @@ func (APIConnReverseTest) GetNodeByName(ctx context.Context, name string) (*api.
 	}, nil
 }
 
-func (APIConnReverseTest) GetNamespaceByName(name string) (*api.Namespace, error) {
-	return &api.Namespace{
-		ObjectMeta: meta.ObjectMeta{
-			Name: name,
-		},
+func (APIConnReverseTest) GetNamespaceByName(name string) (*object.Namespace, error) {
+	return &object.Namespace{
+		Name: name,
 	}, nil
 }