Support List() single-matchers

pkg/registry/generic/etcd/etcd.go

@@ -145,9 +145,20 @@ func (e *Etcd) List(ctx api.Context, label labels.Selector, field fields.Selecto
 // ListPredicate returns a list of all the items matching m.
 func (e *Etcd) ListPredicate(ctx api.Context, m generic.Matcher) (runtime.Object, error) {
 	list := e.NewListFunc()
-	err := e.Helper.ExtractToList(e.KeyRootFunc(ctx), list)
-	if err != nil {
-		return nil, err
+	if name, ok := m.MatchesSingle(); ok {
+		key, err := e.KeyFunc(ctx, name)
+		if err != nil {
+			return nil, err
+		}
+		err = e.Helper.ExtractObjToList(key, list)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		err := e.Helper.ExtractToList(e.KeyRootFunc(ctx), list)
+		if err != nil {
+			return nil, err
+		}
 	}
 	return generic.FilterList(list, m, generic.DecoratorFunc(e.Decorator))
 }

pkg/registry/generic/etcd/etcd_test.go

@@ -126,6 +126,11 @@ func TestEtcdList(t *testing.T) {
 		Spec:       api.PodSpec{Host: "machine"},
 	}
 
+	singleElemListResp := &etcd.Response{
+		Node: &etcd.Node{
+			Value: runtime.EncodeOrDie(testapi.Codec(), podA),
+		},
+	}
 	normalListResp := &etcd.Response{
 		Node: &etcd.Node{
 			Nodes: []*etcd.Node{
@@ -174,7 +179,7 @@ func TestEtcdList(t *testing.T) {
 		},
 		"normalFiltered": {
 			in: tools.EtcdResponseWithError{
-				R: normalListResp,
+				R: singleElemListResp,
 				E: nil,
 			},
 			m:       setMatcher{util.NewStringSet("foo")},
@@ -194,7 +199,16 @@ func TestEtcdList(t *testing.T) {
 
 	for name, item := range table {
 		fakeClient, registry := NewTestGenericEtcdRegistry(t)
-		fakeClient.Data[registry.KeyRootFunc(api.NewContext())] = item.in
+		if name, ok := item.m.MatchesSingle(); ok {
+			key, err := registry.KeyFunc(api.NewContext(), name)
+			if err != nil {
+				t.Errorf("Couldn't create key for %v", name)
+				continue
+			}
+			fakeClient.Data[key] = item.in
+		} else {
+			fakeClient.Data[registry.KeyRootFunc(api.NewContext())] = item.in
+		}
 		list, err := registry.ListPredicate(api.NewContext(), item.m)
 		if e, a := item.succeed, err == nil; e != a {
 			t.Errorf("%v: expected %v, got %v", name, e, a)

pkg/registry/pod/etcd/etcd_test.go

@@ -280,6 +280,15 @@ func TestListPodListSelection(t *testing.T) {
 			},
 		},
 	}
+	fakeEtcdClient.Data["/registry/pods/default/zot"] = tools.EtcdResponseWithError{
+		R: &etcd.Response{
+			Node: &etcd.Node{
+				Value: runtime.EncodeOrDie(latest.Codec, &api.Pod{
+					ObjectMeta: api.ObjectMeta{Name: "zot"},
+				}),
+			},
+		},
+	}
 	storage := NewStorage(helper, nil).Pod
 
 	ctx := api.NewDefaultContext()

pkg/tools/etcd_helper.go

@@ -151,6 +151,33 @@ func (h *EtcdHelper) ExtractToList(key string, listObj runtime.Object) error {
 	return nil
 }
 
+// ExtractObjToList unmarshals json found at key and opaques it into a *List api object
+// (an object that satisfies the runtime.IsList definition).
+func (h *EtcdHelper) ExtractObjToList(key string, listObj runtime.Object) error {
+	listPtr, err := runtime.GetItemsPtr(listObj)
+	if err != nil {
+		return err
+	}
+
+	response, err := h.Client.Get(key, false, false)
+	if err != nil && !IsEtcdNotFound(err) {
+		return err
+	}
+
+	nodes := make([]*etcd.Node, 0)
+	nodes = append(nodes, response.Node)
+
+	if err := h.decodeNodeList(nodes, listPtr); err != nil {
+		return err
+	}
+	if h.Versioner != nil {
+		if err := h.Versioner.UpdateList(listObj, response.EtcdIndex); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // ExtractObj unmarshals json found at key into objPtr. On a not found error, will either return
 // a zero object of the requested type, or an error, depending on ignoreNotFound. Treats
 // empty responses and nil response nodes exactly like a not found error.