Merge pull request #7449 from vmarmol/runtime-network-plugins

Move network plugin TearDown to DockerManager

pkg/kubelet/dockertools/docker.go

@@ -29,6 +29,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/credentialprovider"
 	kubecontainer "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/container"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/leaky"
+	kubeletTypes "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/docker/docker/pkg/parsers"
@@ -68,9 +69,6 @@ type DockerInterface interface {
 	StartExec(string, docker.StartExecOptions) error
 }
 
-// DockerID is an ID of docker container. It is a type to make it clear when we're working with docker container Ids
-type DockerID string
-
 // KubeletContainerName encapsulates a pod name and a Kubernetes container name.
 type KubeletContainerName struct {
 	PodFullName   string
@@ -174,7 +172,7 @@ func (p throttledDockerPuller) IsImagePresent(name string) (bool, error) {
 }
 
 // DockerContainers is a map of containers
-type DockerContainers map[DockerID]*docker.APIContainers
+type DockerContainers map[kubeletTypes.DockerID]*docker.APIContainers
 
 func (c DockerContainers) FindPodContainer(podFullName string, uid types.UID, containerName string) (*docker.APIContainers, bool, uint64) {
 	for _, dockerContainer := range c {
@@ -319,7 +317,7 @@ func GetKubeletDockerContainers(client DockerInterface, allContainers bool) (Doc
 			glog.V(3).Infof("Docker Container: %s is not managed by kubelet.", container.Names[0])
 			continue
 		}
-		result[DockerID(container.ID)] = container
+		result[kubeletTypes.DockerID(container.ID)] = container
 	}
 	return result, nil
 }

pkg/kubelet/dockertools/docker_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/record"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/credentialprovider"
 	kubecontainer "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/container"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/network"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	docker "github.com/fsouza/go-dockerclient"
@@ -392,7 +393,8 @@ func TestIsImagePresent(t *testing.T) {
 func TestGetRunningContainers(t *testing.T) {
 	fakeDocker := &FakeDockerClient{Errors: make(map[string]error)}
 	fakeRecorder := &record.FakeRecorder{}
-	containerManager := NewDockerManager(fakeDocker, fakeRecorder, nil, nil, PodInfraContainerImage, 0, 0, "", kubecontainer.FakeOS{})
+	np, _ := network.InitNetworkPlugin([]network.NetworkPlugin{}, "", network.NewFakeHost(nil))
+	containerManager := NewDockerManager(fakeDocker, fakeRecorder, nil, nil, PodInfraContainerImage, 0, 0, "", kubecontainer.FakeOS{}, np)
 	tests := []struct {
 		containers  map[string]*docker.Container
 		inputIDs    []string
@@ -657,7 +659,8 @@ func TestFindContainersByPod(t *testing.T) {
 		},
 	}
 	fakeClient := &FakeDockerClient{}
-	containerManager := NewDockerManager(fakeClient, &record.FakeRecorder{}, nil, nil, PodInfraContainerImage, 0, 0, "", kubecontainer.FakeOS{})
+	np, _ := network.InitNetworkPlugin([]network.NetworkPlugin{}, "", network.NewFakeHost(nil))
+	containerManager := NewDockerManager(fakeClient, &record.FakeRecorder{}, nil, nil, PodInfraContainerImage, 0, 0, "", kubecontainer.FakeOS{}, np)
 	for i, test := range tests {
 		fakeClient.ContainerList = test.containerList
 		fakeClient.ExitedContainerList = test.exitedContainerList

pkg/kubelet/dockertools/manager.go

@@ -34,6 +34,8 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/capabilities"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/record"
 	kubecontainer "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/container"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/network"
+	kubeletTypes "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/fsouza/go-dockerclient"
@@ -81,6 +83,9 @@ type DockerManager struct {
 
 	// Directory of container logs.
 	containerLogsDir string
+
+	// Network plugin.
+	networkPlugin network.NetworkPlugin
 }
 
 func NewDockerManager(
@@ -92,7 +97,8 @@ func NewDockerManager(
 	qps float32,
 	burst int,
 	containerLogsDir string,
-	osInterface kubecontainer.OSInterface) *DockerManager {
+	osInterface kubecontainer.OSInterface,
+	networkPlugin network.NetworkPlugin) *DockerManager {
 	// Work out the location of the Docker runtime, defaulting to /var/lib/docker
 	// if there are any problems.
 	dockerRoot := "/var/lib/docker"
@@ -135,6 +141,7 @@ func NewDockerManager(
 		Puller:                 newDockerPuller(client, qps, burst),
 		dockerRoot:             dockerRoot,
 		containerLogsDir:       containerLogsDir,
+		networkPlugin:          networkPlugin,
 	}
 }
 
@@ -941,13 +948,24 @@ func (dm *DockerManager) PortForward(pod *kubecontainer.Pod, port uint16, stream
 
 // Kills all containers in the specified pod
 func (dm *DockerManager) KillPod(pod kubecontainer.Pod) error {
-	// Send the kills in parallel since they may take a long time.
+	// Send the kills in parallel since they may take a long time. Len + 1 since there
-	errs := make(chan error, len(pod.Containers))
+	// can be Len errors + the networkPlugin teardown error.
+	errs := make(chan error, len(pod.Containers)+1)
 	wg := sync.WaitGroup{}
 	for _, container := range pod.Containers {
 		wg.Add(1)
 		go func(container *kubecontainer.Container) {
 			defer util.HandleCrash()
+
+			// TODO: Handle this without signaling the pod infra container to
+			// adapt to the generic container runtime.
+			if container.Name == PodInfraContainerName {
+				err := dm.networkPlugin.TearDownPod(pod.Namespace, pod.Name, kubeletTypes.DockerID(container.ID))
+				if err != nil {
+					glog.Errorf("Failed tearing down the infra container: %v", err)
+					errs <- err
+				}
+			}
 			err := dm.KillContainer(container.ID)
 			if err != nil {
 				glog.Errorf("Failed to delete container: %v; Skipping pod %q", err, pod.ID)
@@ -988,7 +1006,7 @@ func (dm *DockerManager) KillContainer(containerID types.UID) error {
 }
 
 // Run a single container from a pod. Returns the docker container ID
-func (dm *DockerManager) RunContainer(pod *api.Pod, container *api.Container, generator kubecontainer.RunContainerOptionsGenerator, runner kubecontainer.HandlerRunner, netMode, ipcMode string) (DockerID, error) {
+func (dm *DockerManager) RunContainer(pod *api.Pod, container *api.Container, generator kubecontainer.RunContainerOptionsGenerator, runner kubecontainer.HandlerRunner, netMode, ipcMode string) (kubeletTypes.DockerID, error) {
 	ref, err := kubecontainer.GenerateContainerRef(pod, container)
 	if err != nil {
 		glog.Errorf("Couldn't make a ref to pod %v, container %v: '%v'", pod.Name, container.Name, err)
@@ -1013,7 +1031,7 @@ func (dm *DockerManager) RunContainer(pod *api.Pod, container *api.Container, ge
 		handlerErr := runner.Run(id, pod, container, container.Lifecycle.PostStart)
 		if handlerErr != nil {
 			dm.KillContainer(types.UID(id))
-			return DockerID(""), fmt.Errorf("failed to call event handler: %v", handlerErr)
+			return kubeletTypes.DockerID(""), fmt.Errorf("failed to call event handler: %v", handlerErr)
 		}
 	}
 
@@ -1027,11 +1045,11 @@ func (dm *DockerManager) RunContainer(pod *api.Pod, container *api.Container, ge
 	if err = dm.os.Symlink(containerLogFile, symlinkFile); err != nil {
 		glog.Errorf("Failed to create symbolic link to the log file of pod %q container %q: %v", podFullName, container.Name, err)
 	}
-	return DockerID(id), err
+	return kubeletTypes.DockerID(id), err
 }
 
 // CreatePodInfraContainer starts the pod infra container for a pod. Returns the docker container ID of the newly created container.
-func (dm *DockerManager) CreatePodInfraContainer(pod *api.Pod, generator kubecontainer.RunContainerOptionsGenerator, runner kubecontainer.HandlerRunner) (DockerID, error) {
+func (dm *DockerManager) CreatePodInfraContainer(pod *api.Pod, generator kubecontainer.RunContainerOptionsGenerator, runner kubecontainer.HandlerRunner) (kubeletTypes.DockerID, error) {
 	// Use host networking if specified.
 	netNamespace := ""
 	var ports []api.ContainerPort

pkg/kubelet/kubelet.go

@@ -43,6 +43,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/envvars"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/metrics"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/network"
+	kubeletTypes "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/probe"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
@@ -202,16 +203,6 @@ func NewMainKubelet(
 	statusManager := newStatusManager(kubeClient)
 	readinessManager := kubecontainer.NewReadinessManager()
 	containerRefManager := kubecontainer.NewRefManager()
-	containerManager := dockertools.NewDockerManager(
-		dockerClient,
-		recorder,
-		readinessManager,
-		containerRefManager,
-		podInfraContainerImage,
-		pullQPS,
-		pullBurst,
-		containerLogsDir,
-		osInterface)
 
 	volumeManager := newVolumeManager()
 
@@ -223,7 +214,6 @@ func NewMainKubelet(
 		resyncInterval:                 resyncInterval,
 		containerRefManager:            containerRefManager,
 		readinessManager:               readinessManager,
-		runner:                         containerManager,
 		httpClient:                     &http.Client{},
 		sourcesReady:                   sourcesReady,
 		clusterDomain:                  clusterDomain,
@@ -240,12 +230,30 @@ func NewMainKubelet(
 		volumeManager:                  volumeManager,
 		cloud:                          cloud,
 		nodeRef:                        nodeRef,
-		containerManager:               containerManager,
 		nodeStatusUpdateFrequency:      nodeStatusUpdateFrequency,
 		resourceContainer:              resourceContainer,
 		os:                             osInterface,
 	}
 
+	if plug, err := network.InitNetworkPlugin(networkPlugins, networkPluginName, &networkHost{klet}); err != nil {
+		return nil, err
+	} else {
+		klet.networkPlugin = plug
+	}
+	containerManager := dockertools.NewDockerManager(
+		dockerClient,
+		recorder,
+		readinessManager,
+		containerRefManager,
+		podInfraContainerImage,
+		pullQPS,
+		pullBurst,
+		containerLogsDir,
+		osInterface,
+		klet.networkPlugin)
+	klet.runner = containerManager
+	klet.containerManager = containerManager
+
 	klet.podManager = newBasicPodManager(klet.kubeClient)
 	klet.prober = newProber(klet.runner, klet.readinessManager, klet.containerRefManager, klet.recorder)
 	klet.handlerRunner = newHandlerRunner(klet.httpClient, klet.runner, klet.containerManager)
@@ -266,11 +274,6 @@ func NewMainKubelet(
 		return nil, err
 	}
 
-	if plug, err := network.InitNetworkPlugin(networkPlugins, networkPluginName, &networkHost{klet}); err != nil {
-		return nil, err
-	} else {
-		klet.networkPlugin = plug
-	}
 	// If the container logs directory does not exist, create it.
 	if _, err := os.Stat(containerLogsDir); err != nil {
 		if err := osInterface.Mkdir(containerLogsDir, 0755); err != nil {
@@ -887,27 +890,7 @@ func (kl *Kubelet) pullImage(pod *api.Pod, container *api.Container) error {
 
 // Kill all running containers in a pod (includes the pod infra container).
 func (kl *Kubelet) killPod(pod kubecontainer.Pod) error {
-	// TODO(vmarmol): Consider handling non-Docker runtimes, the plugins are not friendly to it today.
+	return kl.containerManager.KillPod(pod)
-	container, err := kl.containerManager.GetPodInfraContainer(pod)
-	errList := []error{}
-	if err == nil {
-		// Call the networking plugin for teardown.
-		err = kl.networkPlugin.TearDownPod(pod.Namespace, pod.Name, dockertools.DockerID(container.ID))
-		if err != nil {
-			glog.Errorf("Failed tearing down the network plugin for pod %q: %v", pod.ID, err)
-			errList = append(errList, err)
-		}
-	}
-
-	err = kl.containerManager.KillPod(pod)
-	if err != nil {
-		errList = append(errList, err)
-	}
-
-	if len(errList) > 0 {
-		return utilErrors.NewAggregate(errList)
-	}
-	return nil
 }
 
 type empty struct{}
@@ -973,9 +956,9 @@ func shouldContainerBeRestarted(container *api.Container, pod *api.Pod, podStatu
 // - all running containers which are NOT contained in containersToKeep should be killed.
 type podContainerChangesSpec struct {
 	startInfraContainer bool
-	infraContainerId    dockertools.DockerID
+	infraContainerId    kubeletTypes.DockerID
 	containersToStart   map[int]empty
-	containersToKeep    map[dockertools.DockerID]int
+	containersToKeep    map[kubeletTypes.DockerID]int
 }
 
 func (kl *Kubelet) computePodContainerChanges(pod *api.Pod, runningPod kubecontainer.Pod, podStatus api.PodStatus) (podContainerChangesSpec, error) {
@@ -984,11 +967,11 @@ func (kl *Kubelet) computePodContainerChanges(pod *api.Pod, runningPod kubeconta
 	glog.V(4).Infof("Syncing Pod %+v, podFullName: %q, uid: %q", pod, podFullName, uid)
 
 	containersToStart := make(map[int]empty)
-	containersToKeep := make(map[dockertools.DockerID]int)
+	containersToKeep := make(map[kubeletTypes.DockerID]int)
 	createPodInfraContainer := false
 
 	var err error
-	var podInfraContainerID dockertools.DockerID
+	var podInfraContainerID kubeletTypes.DockerID
 	var changed bool
 	podInfraContainer := runningPod.FindContainerByName(dockertools.PodInfraContainerName)
 	if podInfraContainer != nil {
@@ -1007,7 +990,7 @@ func (kl *Kubelet) computePodContainerChanges(pod *api.Pod, runningPod kubeconta
 	} else {
 		glog.V(4).Infof("Pod infra container looks good, keep it %q", podFullName)
 		createPodInfraContainer = false
-		podInfraContainerID = dockertools.DockerID(podInfraContainer.ID)
+		podInfraContainerID = kubeletTypes.DockerID(podInfraContainer.ID)
 		containersToKeep[podInfraContainerID] = -1
 	}
 
@@ -1026,7 +1009,7 @@ func (kl *Kubelet) computePodContainerChanges(pod *api.Pod, runningPod kubeconta
 			continue
 		}
 
-		containerID := dockertools.DockerID(c.ID)
+		containerID := kubeletTypes.DockerID(c.ID)
 		hash := c.Hash
 		glog.V(3).Infof("pod %q container %q exists as %v", podFullName, container.Name, containerID)
 
@@ -1074,7 +1057,7 @@ func (kl *Kubelet) computePodContainerChanges(pod *api.Pod, runningPod kubeconta
 
 	// If Infra container is the last running one, we don't want to keep it.
 	if !createPodInfraContainer && len(containersToStart) == 0 && len(containersToKeep) == 1 {
-		containersToKeep = make(map[dockertools.DockerID]int)
+		containersToKeep = make(map[kubeletTypes.DockerID]int)
 	}
 
 	return podContainerChangesSpec{
@@ -1147,7 +1130,7 @@ func (kl *Kubelet) syncPod(pod *api.Pod, mirrorPod *api.Pod, runningPod kubecont
 	} else {
 		// Otherwise kill any containers in this pod which are not specified as ones to keep.
 		for _, container := range runningPod.Containers {
-			_, keep := containerChanges.containersToKeep[dockertools.DockerID(container.ID)]
+			_, keep := containerChanges.containersToKeep[kubeletTypes.DockerID(container.ID)]
 			if !keep {
 				glog.V(3).Infof("Killing unwanted container %+v", container)
 				err = kl.containerManager.KillContainer(container.ID)

pkg/kubelet/kubelet_test.go

@@ -105,7 +105,7 @@ func newTestKubelet(t *testing.T) *TestKubelet {
 	podManager, fakeMirrorClient := newFakePodManager()
 	kubelet.podManager = podManager
 	kubelet.containerRefManager = kubecontainer.NewRefManager()
-	kubelet.containerManager = dockertools.NewDockerManager(fakeDocker, fakeRecorder, kubelet.readinessManager, kubelet.containerRefManager, dockertools.PodInfraContainerImage, 0, 0, "", kubelet.os)
+	kubelet.containerManager = dockertools.NewDockerManager(fakeDocker, fakeRecorder, kubelet.readinessManager, kubelet.containerRefManager, dockertools.PodInfraContainerImage, 0, 0, "", kubelet.os, kubelet.networkPlugin)
 	kubelet.runtimeCache = kubecontainer.NewFakeRuntimeCache(kubelet.containerManager)
 	kubelet.podWorkers = newPodWorkers(
 		kubelet.runtimeCache,

pkg/kubelet/network/exec/exec.go

@@ -54,8 +54,8 @@ import (
 	"path"
 	"strings"
 
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/network"
+	kubeletTypes "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/types"
 	utilexec "github.com/GoogleCloudPlatform/kubernetes/pkg/util/exec"
 	"github.com/golang/glog"
 )
@@ -125,13 +125,13 @@ func (plugin *execNetworkPlugin) validate() error {
 	return nil
 }
 
-func (plugin *execNetworkPlugin) SetUpPod(namespace string, name string, id dockertools.DockerID) error {
+func (plugin *execNetworkPlugin) SetUpPod(namespace string, name string, id kubeletTypes.DockerID) error {
 	out, err := utilexec.New().Command(plugin.getExecutable(), setUpCmd, namespace, name, string(id)).CombinedOutput()
 	glog.V(5).Infof("SetUpPod 'exec' network plugin output: %s, %v", string(out), err)
 	return err
 }
 
-func (plugin *execNetworkPlugin) TearDownPod(namespace string, name string, id dockertools.DockerID) error {
+func (plugin *execNetworkPlugin) TearDownPod(namespace string, name string, id kubeletTypes.DockerID) error {
 	out, err := utilexec.New().Command(plugin.getExecutable(), tearDownCmd, namespace, name, string(id)).CombinedOutput()
 	glog.V(5).Infof("TearDownPod 'exec' network plugin output: %s, %v", string(out), err)
 	return err

pkg/kubelet/network/plugins.go

@@ -22,7 +22,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
+	kubeletTypes "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/types"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/errors"
 	"github.com/golang/glog"
@@ -43,10 +43,10 @@ type NetworkPlugin interface {
 	// SetUpPod is the method called after the infra container of
 	// the pod has been created but before the other containers of the
 	// pod are launched.
-	SetUpPod(namespace string, name string, podInfraContainerID dockertools.DockerID) error
+	SetUpPod(namespace string, name string, podInfraContainerID kubeletTypes.DockerID) error
 
 	// TearDownPod is the method called before a pod's infra container will be deleted
-	TearDownPod(namespace string, name string, podInfraContainerID dockertools.DockerID) error
+	TearDownPod(namespace string, name string, podInfraContainerID kubeletTypes.DockerID) error
 }
 
 // Host is an interface that plugins can use to access the kubelet.
@@ -113,10 +113,10 @@ func (plugin *noopNetworkPlugin) Name() string {
 	return DefaultPluginName
 }
 
-func (plugin *noopNetworkPlugin) SetUpPod(namespace string, name string, id dockertools.DockerID) error {
+func (plugin *noopNetworkPlugin) SetUpPod(namespace string, name string, id kubeletTypes.DockerID) error {
 	return nil
 }
 
-func (plugin *noopNetworkPlugin) TearDownPod(namespace string, name string, id dockertools.DockerID) error {
+func (plugin *noopNetworkPlugin) TearDownPod(namespace string, name string, id kubeletTypes.DockerID) error {
 	return nil
 }

pkg/kubelet/pod_workers_test.go

@@ -25,6 +25,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/record"
 	kubecontainer "github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/container"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/network"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/types"
 )
 
@@ -40,7 +41,8 @@ func newPod(uid, name string) *api.Pod {
 func createPodWorkers() (*podWorkers, map[types.UID][]string) {
 	fakeDocker := &dockertools.FakeDockerClient{}
 	fakeRecorder := &record.FakeRecorder{}
-	dockerManager := dockertools.NewDockerManager(fakeDocker, fakeRecorder, nil, nil, dockertools.PodInfraContainerImage, 0, 0, "", kubecontainer.FakeOS{})
+	np, _ := network.InitNetworkPlugin([]network.NetworkPlugin{}, "", network.NewFakeHost(nil))
+	dockerManager := dockertools.NewDockerManager(fakeDocker, fakeRecorder, nil, nil, dockertools.PodInfraContainerImage, 0, 0, "", kubecontainer.FakeOS{}, np)
 	fakeRuntimeCache := kubecontainer.NewFakeRuntimeCache(dockerManager)
 
 	lock := sync.Mutex{}

pkg/kubelet/runonce_test.go

@@ -157,7 +157,8 @@ func TestRunOnce(t *testing.T) {
 		0,
 		0,
 		"",
-		kubecontainer.FakeOS{})
+		kubecontainer.FakeOS{},
+		kb.networkPlugin)
 	kb.containerManager.Puller = &dockertools.FakeDockerPuller{}
 
 	pods := []*api.Pod{

pkg/kubelet/types/doc.go

@@ -0,0 +1,18 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Common types in the Kubelet.
+package types

pkg/kubelet/types/docker.go

@@ -0,0 +1,20 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package types
+
+// DockerID is an ID of docker container. It is a type to make it clear when we're working with docker container Ids
+type DockerID string