Merge pull request #5730 from yujuhong/static_stats

Kubelet: support retrieving stats using UID of mirror pods

pkg/kubelet/kubelet.go

@@ -95,7 +95,7 @@ type SyncHandler interface {
 	// Syncs current state to match the specified pods. SyncPodType specified what
 	// type of sync is occuring per pod. StartTime specifies the time at which
 	// syncing began (for use in monitoring).
-	SyncPods(pods []api.Pod, podSyncTypes map[types.UID]metrics.SyncPodType, mirrorPods util.StringSet,
+	SyncPods(pods []api.Pod, podSyncTypes map[types.UID]metrics.SyncPodType, mirrorPods mirrorPods,
 		startTime time.Time) error
 }
 
@@ -267,7 +267,7 @@ type Kubelet struct {
 	// similar to pods, this is not immutable and is protected by the same podLock.
 	// Note that Kubelet.pods do not contain mirror pods as they are filtered
 	// out beforehand.
-	mirrorPods util.StringSet
+	mirrorPods mirrorPods
 
 	// A pod status cache stores statuses for pods (both rejected and synced).
 	// Note that currently no thread attempts to acquire podStatusesLock while
@@ -1488,7 +1488,7 @@ func (kl *Kubelet) cleanupOrphanedVolumes(pods []api.Pod, running []*docker.Cont
 }
 
 // SyncPods synchronizes the configured list of pods (desired state) with the host current state.
-func (kl *Kubelet) SyncPods(allPods []api.Pod, podSyncTypes map[types.UID]metrics.SyncPodType, mirrorPods util.StringSet, start time.Time) error {
+func (kl *Kubelet) SyncPods(allPods []api.Pod, podSyncTypes map[types.UID]metrics.SyncPodType, mirrorPods mirrorPods, start time.Time) error {
 	defer func() {
 		metrics.SyncPodsLatency.Observe(metrics.SinceInMicroseconds(start))
 	}()
@@ -1536,7 +1536,7 @@ func (kl *Kubelet) SyncPods(allPods []api.Pod, podSyncTypes map[types.UID]metric
 		}
 
 		// Run the sync in an async manifest worker.
-		kl.podWorkers.UpdatePod(pod, kl.mirrorPods.Has(podFullName), func() {
+		kl.podWorkers.UpdatePod(pod, kl.mirrorPods.HasMirrorPod(uid), func() {
 			metrics.SyncPodLatency.WithLabelValues(podSyncTypes[pod.UID].String()).Observe(metrics.SinceInMicroseconds(start))
 		})
 
@@ -1606,7 +1606,7 @@ func (kl *Kubelet) SyncPods(allPods []api.Pod, podSyncTypes map[types.UID]metric
 	}
 
 	// Remove any orphaned mirror pods.
-	deleteOrphanedMirrorPods(pods, mirrorPods, kl.mirrorManager)
+	deleteOrphanedMirrorPods(mirrorPods, kl.mirrorManager)
 
 	return err
 }
@@ -1885,7 +1885,7 @@ func (kl *Kubelet) GetHostname() string {
 
 // GetPods returns all pods bound to the kubelet and their spec, and the mirror
 // pod map.
-func (kl *Kubelet) GetPods() ([]api.Pod, util.StringSet) {
+func (kl *Kubelet) GetPods() ([]api.Pod, mirrorPods) {
 	kl.podLock.RLock()
 	defer kl.podLock.RUnlock()
 	return append([]api.Pod{}, kl.pods...), kl.mirrorPods
@@ -2057,6 +2057,8 @@ func getPodReadyCondition(spec *api.PodSpec, info api.PodInfo) []api.PodConditio
 
 // GetPodStatus returns information from Docker about the containers in a pod
 func (kl *Kubelet) GetPodStatus(podFullName string, uid types.UID) (api.PodStatus, error) {
+	uid = kl.translatePodUID(uid)
+
 	// Check to see if we have a cached version of the status.
 	cachedPodStatus, found := kl.getPodStatusFromCache(podFullName)
 	if found {
@@ -2119,6 +2121,8 @@ func (kl *Kubelet) ServeLogs(w http.ResponseWriter, req *http.Request) {
 
 // Run a command in a container, returns the combined stdout, stderr as an array of bytes
 func (kl *Kubelet) RunInContainer(podFullName string, uid types.UID, container string, cmd []string) ([]byte, error) {
+	uid = kl.translatePodUID(uid)
+
 	if kl.runner == nil {
 		return nil, fmt.Errorf("no runner specified.")
 	}
@@ -2136,6 +2140,8 @@ func (kl *Kubelet) RunInContainer(podFullName string, uid types.UID, container s
 // ExecInContainer executes a command in a container, connecting the supplied
 // stdin/stdout/stderr to the command's IO streams.
 func (kl *Kubelet) ExecInContainer(podFullName string, uid types.UID, container string, cmd []string, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool) error {
+	uid = kl.translatePodUID(uid)
+
 	if kl.runner == nil {
 		return fmt.Errorf("no runner specified.")
 	}
@@ -2153,6 +2159,8 @@ func (kl *Kubelet) ExecInContainer(podFullName string, uid types.UID, container
 // PortForward connects to the pod's port and copies data between the port
 // and the stream.
 func (kl *Kubelet) PortForward(podFullName string, uid types.UID, port uint16, stream io.ReadWriteCloser) error {
+	uid = kl.translatePodUID(uid)
+
 	if kl.runner == nil {
 		return fmt.Errorf("no runner specified.")
 	}
@@ -2185,8 +2193,30 @@ func (kl *Kubelet) StreamingConnectionIdleTimeout() time.Duration {
 	return kl.streamingConnectionIdleTimeout
 }
 
+// If the UID belongs to a mirror pod, maps it to the UID of its static pod.
+// Otherwise, return the original UID. All public-facing functions should
+// perform this translation for UIDs because user may provide a mirror pod UID,
+// which is not recognized by internal Kubelet functions.
+func (kl *Kubelet) translatePodUID(uid types.UID) types.UID {
+	if uid == "" {
+		return uid
+	}
+
+	kl.podLock.RLock()
+	defer kl.podLock.RUnlock()
+	staticUID, ok := kl.mirrorPods.GetStaticUID(uid)
+	if ok {
+		return staticUID
+	} else {
+		return uid
+	}
+}
+
 // GetContainerInfo returns stats (from Cadvisor) for a container.
 func (kl *Kubelet) GetContainerInfo(podFullName string, uid types.UID, containerName string, req *cadvisorApi.ContainerInfoRequest) (*cadvisorApi.ContainerInfo, error) {
+
+	uid = kl.translatePodUID(uid)
+
 	dockerContainers, err := dockertools.GetKubeletDockerContainers(kl.dockerClient, false)
 	if err != nil {
 		return nil, err

pkg/kubelet/kubelet_test.go

@@ -447,7 +447,7 @@ func TestSyncPodsDoesNothing(t *testing.T) {
 		},
 	}
 	waitGroup.Add(1)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -481,7 +481,7 @@ func TestSyncPodsWithTerminationLog(t *testing.T) {
 		},
 	}
 	waitGroup.Add(1)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -531,7 +531,7 @@ func TestSyncPodsCreatesNetAndContainer(t *testing.T) {
 		},
 	}
 	waitGroup.Add(1)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -585,7 +585,7 @@ func TestSyncPodsCreatesNetAndContainerPullsImage(t *testing.T) {
 		},
 	}
 	waitGroup.Add(1)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -636,7 +636,7 @@ func TestSyncPodsWithPodInfraCreatesContainer(t *testing.T) {
 		},
 	}
 	waitGroup.Add(1)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -694,7 +694,7 @@ func TestSyncPodsWithPodInfraCreatesContainerCallsHandler(t *testing.T) {
 		},
 	}
 	waitGroup.Add(1)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -764,7 +764,7 @@ func TestSyncPodsDeletesWithNoPodInfraContainer(t *testing.T) {
 		},
 	}
 	waitGroup.Add(2)
-	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods(kubelet.pods, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -805,7 +805,7 @@ func TestSyncPodsDeletesWhenSourcesAreReady(t *testing.T) {
 			ID:    "9876",
 		},
 	}
-	if err := kubelet.SyncPods([]api.Pod{}, emptyPodUIDs, util.NewStringSet(), time.Now()); err != nil {
+	if err := kubelet.SyncPods([]api.Pod{}, emptyPodUIDs, *newMirrorPods(), time.Now()); err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
 	// Validate nothing happened.
@@ -813,7 +813,7 @@ func TestSyncPodsDeletesWhenSourcesAreReady(t *testing.T) {
 	fakeDocker.ClearCalls()
 
 	ready = true
-	if err := kubelet.SyncPods([]api.Pod{}, emptyPodUIDs, util.NewStringSet(), time.Now()); err != nil {
+	if err := kubelet.SyncPods([]api.Pod{}, emptyPodUIDs, *newMirrorPods(), time.Now()); err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
 	verifyCalls(t, fakeDocker, []string{"list", "stop", "stop", "inspect_container", "inspect_container"})
@@ -852,7 +852,7 @@ func TestSyncPodsDeletes(t *testing.T) {
 			ID:    "4567",
 		},
 	}
-	err := kubelet.SyncPods([]api.Pod{}, emptyPodUIDs, util.NewStringSet(), time.Now())
+	err := kubelet.SyncPods([]api.Pod{}, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -1731,7 +1731,7 @@ func TestSyncPodsWithPullPolicy(t *testing.T) {
 				},
 			},
 		},
-	}, emptyPodUIDs, util.NewStringSet(), time.Now())
+	}, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
@@ -2936,7 +2936,7 @@ func TestPurgingObsoleteStatusMapEntries(t *testing.T) {
 		t.Fatalf("expected length of status map to be 1. Got map %#v.", kl.podStatuses)
 	}
 	// Sync with empty pods so that the entry in status map will be removed.
-	kl.SyncPods([]api.Pod{}, emptyPodUIDs, util.NewStringSet(), time.Now())
+	kl.SyncPods([]api.Pod{}, emptyPodUIDs, *newMirrorPods(), time.Now())
 	if len(kl.podStatuses) != 0 {
 		t.Fatalf("expected length of status map to be 0. Got map %#v.", kl.podStatuses)
 	}
@@ -3183,23 +3183,119 @@ func TestDeleteOrphanedMirrorPods(t *testing.T) {
 	testKubelet.fakeCadvisor.On("MachineInfo").Return(&cadvisorApi.MachineInfo{}, nil)
 	kl := testKubelet.kubelet
 	manager := testKubelet.fakeMirrorManager
-	orphanedPodNames := []string{"pod1_ns", "pod2_ns"}
+	orphanPods := []api.Pod{
-	mirrorPods := util.NewStringSet()
+		{
-	for _, name := range orphanedPodNames {
+			ObjectMeta: api.ObjectMeta{
-		mirrorPods.Insert(name)
+				UID:       "12345678",
+				Name:      "pod1",
+				Namespace: "ns",
+				Annotations: map[string]string{
+					ConfigSourceAnnotationKey: "api",
+					ConfigMirrorAnnotationKey: "mirror",
+				},
+			},
+		},
+		{
+			ObjectMeta: api.ObjectMeta{
+				UID:       "12345679",
+				Name:      "pod2",
+				Namespace: "ns",
+				Annotations: map[string]string{
+					ConfigSourceAnnotationKey: "api",
+					ConfigMirrorAnnotationKey: "mirror",
+				},
+			},
+		},
+	}
+
+	mirrorPods := newMirrorPods()
+	for _, pod := range orphanPods {
+		mirrorPods.Insert(&pod)
 	}
 	// Sync with an empty pod list to delete all mirror pods.
-	err := kl.SyncPods([]api.Pod{}, emptyPodUIDs, mirrorPods, time.Now())
+	err := kl.SyncPods([]api.Pod{}, emptyPodUIDs, *mirrorPods, time.Now())
 	if err != nil {
 		t.Errorf("unexpected error: %v", err)
 	}
 	if manager.NumOfPods() != 0 {
 		t.Errorf("expected zero mirror pods, got %v", manager.GetPods())
 	}
-	for _, name := range orphanedPodNames {
+	for _, pod := range orphanPods {
+		name := GetPodFullName(&pod)
 		creates, deletes := manager.GetCounts(name)
 		if creates != 0 || deletes != 1 {
 			t.Errorf("expected 0 creation and one deletion of %q, got %d, %d", name, creates, deletes)
 		}
 	}
 }
+
+func TestGetContainerInfoForMirrorPods(t *testing.T) {
+	// pods contain one static and one mirror pod with the same name but
+	// different UIDs.
+	pods := []api.Pod{
+		{
+			ObjectMeta: api.ObjectMeta{
+				UID:       "1234",
+				Name:      "qux",
+				Namespace: "ns",
+				Annotations: map[string]string{
+					ConfigSourceAnnotationKey: "file",
+				},
+			},
+			Spec: api.PodSpec{
+				Containers: []api.Container{
+					{Name: "foo"},
+				},
+			},
+		},
+		{
+			ObjectMeta: api.ObjectMeta{
+				UID:       "5678",
+				Name:      "qux",
+				Namespace: "ns",
+				Annotations: map[string]string{
+					ConfigSourceAnnotationKey: "api",
+					ConfigMirrorAnnotationKey: "mirror",
+				},
+			},
+			Spec: api.PodSpec{
+				Containers: []api.Container{
+					{Name: "foo"},
+				},
+			},
+		},
+	}
+
+	containerID := "ab2cdf"
+	containerPath := fmt.Sprintf("/docker/%v", containerID)
+	containerInfo := cadvisorApi.ContainerInfo{
+		ContainerReference: cadvisorApi.ContainerReference{
+			Name: containerPath,
+		},
+	}
+
+	testKubelet := newTestKubelet(t)
+	kubelet := testKubelet.kubelet
+	fakeDocker := testKubelet.fakeDocker
+	mockCadvisor := testKubelet.fakeCadvisor
+	cadvisorReq := &cadvisorApi.ContainerInfoRequest{}
+	mockCadvisor.On("DockerContainer", containerID, cadvisorReq).Return(containerInfo, nil)
+
+	fakeDocker.ContainerList = []docker.APIContainers{
+		{
+			ID:    containerID,
+			Names: []string{"/k8s_foo_qux_ns_1234_42"},
+		},
+	}
+
+	kubelet.pods, kubelet.mirrorPods = filterAndCategorizePods(pods)
+	// Use the mirror pod UID to retrieve the stats.
+	stats, err := kubelet.GetContainerInfo("qux_ns", "5678", "foo", cadvisorReq)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if stats == nil {
+		t.Fatalf("stats should not be nil")
+	}
+	mockCadvisor.AssertExpectations(t)
+}

pkg/kubelet/mirror_manager.go

@@ -21,7 +21,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
 	"github.com/golang/glog"
 )
 
@@ -86,17 +86,12 @@ func (self *basicMirrorManager) DeleteMirrorPod(podFullName string) error {
 }
 
 // Delete all orphaned mirror pods.
-func deleteOrphanedMirrorPods(pods []api.Pod, mirrorPods util.StringSet, manager mirrorManager) {
+func deleteOrphanedMirrorPods(mirrorPods mirrorPods, manager mirrorManager) {
-	existingPods := util.NewStringSet()
+	podFullNames := mirrorPods.GetOrphanedMirrorPodNames()
-	for _, pod := range pods {
+	for _, podFullName := range podFullNames {
-		existingPods.Insert(GetPodFullName(&pod))
-	}
-	for podFullName := range mirrorPods {
-		if !existingPods.Has(podFullName) {
 		manager.DeleteMirrorPod(podFullName)
 	}
 }
-}
 
 // Helper functions.
 func getPodSource(pod *api.Pod) (string, error) {
@@ -123,16 +118,90 @@ func isMirrorPod(pod *api.Pod) bool {
 
 // This function separate the mirror pods from regular pods to
 // facilitate pods syncing and mirror pod creation/deletion.
-func filterAndCategorizePods(pods []api.Pod) ([]api.Pod, util.StringSet) {
+func filterAndCategorizePods(pods []api.Pod) ([]api.Pod, mirrorPods) {
 	filteredPods := []api.Pod{}
-	mirrorPods := util.NewStringSet()
+	mirrorPods := newMirrorPods()
+
 	for _, pod := range pods {
-		name := GetPodFullName(&pod)
+		mirrorPods.Insert(&pod)
-		if isMirrorPod(&pod) {
+		if !isMirrorPod(&pod) {
-			mirrorPods.Insert(name)
-		} else {
 			filteredPods = append(filteredPods, pod)
 		}
 	}
-	return filteredPods, mirrorPods
+	return filteredPods, *mirrorPods
+}
+
+// mirrorPods is thread-compatible.
+// TODO (yujuhong): Replace this with a pod manager that manages both regular
+// pods and mirror pods.
+type mirrorPods struct {
+	// Static pod UIDs indexed by pod full name.
+	static map[string]types.UID
+	// Mirror pod UIDs indexed by pod full name.
+	mirror map[string]types.UID
+
+	// Bi-directional UID mappings.
+	staticToMirror map[types.UID]types.UID
+	mirrorToStatic map[types.UID]types.UID
+}
+
+func newMirrorPods() *mirrorPods {
+	mirrorPods := mirrorPods{}
+	mirrorPods.static = make(map[string]types.UID)
+	mirrorPods.mirror = make(map[string]types.UID)
+	mirrorPods.staticToMirror = make(map[types.UID]types.UID)
+	mirrorPods.mirrorToStatic = make(map[types.UID]types.UID)
+	return &mirrorPods
+}
+
+func (self *mirrorPods) Insert(pod *api.Pod) {
+	podFullName := GetPodFullName(pod)
+	if isMirrorPod(pod) {
+		self.mirror[podFullName] = pod.UID
+	} else if isStaticPod(pod) {
+		self.static[podFullName] = pod.UID
+	}
+	staticUID, found1 := self.static[podFullName]
+	mirrorUID, found2 := self.mirror[podFullName]
+	// Update the UID mappings.
+	if found1 && found2 {
+		self.staticToMirror[staticUID] = mirrorUID
+		self.mirrorToStatic[mirrorUID] = staticUID
+	}
+}
+
+func (self *mirrorPods) HasStaticPod(key types.UID) bool {
+	_, ok := self.mirrorToStatic[key]
+	return ok
+}
+
+func (self *mirrorPods) HasMirrorPod(key types.UID) bool {
+	_, ok := self.staticToMirror[key]
+	return ok
+}
+
+func (self *mirrorPods) GetMirrorUID(key types.UID) (types.UID, bool) {
+	value, ok := self.staticToMirror[key]
+	if !ok {
+		return "", false
+	}
+	return value, true
+}
+
+func (self *mirrorPods) GetStaticUID(key types.UID) (types.UID, bool) {
+	value, ok := self.mirrorToStatic[key]
+	if !ok {
+		return "", false
+	}
+	return value, true
+}
+
+func (self *mirrorPods) GetOrphanedMirrorPodNames() []string {
+	orphanedPodNames := []string{}
+	for podFullName := range self.mirror {
+		if _, ok := self.static[podFullName]; !ok {
+			orphanedPodNames = append(orphanedPodNames, podFullName)
+		}
+	}
+	return orphanedPodNames
 }

pkg/kubelet/mirror_manager_test.go

@@ -121,7 +121,7 @@ func TestFilterOutMirrorPods(t *testing.T) {
 	if !reflect.DeepEqual(expectedPods, actualPods) {
 		t.Errorf("expected %#v, got %#v", expectedPods, actualPods)
 	}
-	if !actualMirrorPods.Has(GetPodFullName(&mirrorPod)) {
+	if _, ok := actualMirrorPods.mirror[GetPodFullName(&mirrorPod)]; !ok {
 		t.Errorf("mirror pod is not recorded")
 	}
 }

pkg/kubelet/server.go

@@ -37,7 +37,6 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/httplog"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/httpstream"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/httpstream/spdy"
 	"github.com/golang/glog"
@@ -83,7 +82,7 @@ type HostInterface interface {
 	GetRootInfo(req *cadvisorApi.ContainerInfoRequest) (*cadvisorApi.ContainerInfo, error)
 	GetDockerVersion() ([]uint, error)
 	GetCachedMachineInfo() (*cadvisorApi.MachineInfo, error)
-	GetPods() ([]api.Pod, util.StringSet)
+	GetPods() ([]api.Pod, mirrorPods)
 	GetPodByName(namespace, name string) (*api.Pod, bool)
 	GetPodStatus(name string, uid types.UID) (api.PodStatus, error)
 	RunInContainer(name string, uid types.UID, container string, cmd []string) ([]byte, error)

pkg/kubelet/server_test.go

@@ -33,7 +33,6 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/httpstream"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/httpstream/spdy"
 	cadvisorApi "github.com/google/cadvisor/info/v1"
@@ -45,7 +44,7 @@ type fakeKubelet struct {
 	containerInfoFunc                  func(podFullName string, uid types.UID, containerName string, req *cadvisorApi.ContainerInfoRequest) (*cadvisorApi.ContainerInfo, error)
 	rootInfoFunc                       func(query *cadvisorApi.ContainerInfoRequest) (*cadvisorApi.ContainerInfo, error)
 	machineInfoFunc                    func() (*cadvisorApi.MachineInfo, error)
-	podsFunc                           func() ([]api.Pod, util.StringSet)
+	podsFunc                           func() ([]api.Pod, mirrorPods)
 	logFunc                            func(w http.ResponseWriter, req *http.Request)
 	runFunc                            func(podFullName string, uid types.UID, containerName string, cmd []string) ([]byte, error)
 	dockerVersionFunc                  func() ([]uint, error)
@@ -80,7 +79,7 @@ func (fk *fakeKubelet) GetCachedMachineInfo() (*cadvisorApi.MachineInfo, error)
 	return fk.machineInfoFunc()
 }
 
-func (fk *fakeKubelet) GetPods() ([]api.Pod, util.StringSet) {
+func (fk *fakeKubelet) GetPods() ([]api.Pod, mirrorPods) {
 	return fk.podsFunc()
 }