Add a dockershim package

Add a new docker integration with kubelet using the new runtime API.
This change adds the package with some skeletons, and implements some
of the basic operations.

pkg/kubelet/container/kuberuntime.go

@@ -22,9 +22,8 @@ import (
 	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
 )
 
-// RuntimeService interface defines the interfaces that should be implemented
-// by a container runtime.
-// Thread safety is required from implementations of this interface.
+// RuntimeService interface should be implemented by a container runtime.
+// The methods should be thread-safe.
 type RuntimeService interface {
 	// Version returns the runtime name, runtime version and runtime API version
 	Version(apiVersion string) (*runtimeApi.VersionResponse, error)
@@ -33,40 +32,39 @@ type RuntimeService interface {
 	CreatePodSandbox(config *runtimeApi.PodSandboxConfig) (string, error)
 	// StopPodSandbox stops the sandbox. If there are any running containers in the
 	// sandbox, they should be force terminated.
-	StopPodSandbox(podSandBoxID string) error
-	// DeletePodSandbox deletes the sandbox. If there are any running containers in the
-	// sandbox, they should be force deleted.
-	DeletePodSandbox(podSandBoxID string) error
+	StopPodSandbox(podSandboxID string) error
+	// DeletePodSandbox deletes the sandbox. If there are running containers in the
+	// sandbox, they should be forcibly deleted.
+	DeletePodSandbox(podSandboxID string) error
 	// PodSandboxStatus returns the Status of the PodSandbox.
-	PodSandboxStatus(podSandBoxID string) (*runtimeApi.PodSandboxStatus, error)
-	// ListPodSandbox returns a list of SandBox.
+	PodSandboxStatus(podSandboxID string) (*runtimeApi.PodSandboxStatus, error)
+	// ListPodSandbox returns a list of Sandbox.
 	ListPodSandbox(filter *runtimeApi.PodSandboxFilter) ([]*runtimeApi.PodSandbox, error)
-	// CreateContainer creates a new container in specified PodSandbox
-	CreateContainer(podSandBoxID string, config *runtimeApi.ContainerConfig, sandboxConfig *runtimeApi.PodSandboxConfig) (string, error)
+	// CreateContainer creates a new container in specified PodSandbox.
+	CreateContainer(podSandboxID string, config *runtimeApi.ContainerConfig, sandboxConfig *runtimeApi.PodSandboxConfig) (string, error)
 	// StartContainer starts the container.
 	StartContainer(rawContainerID string) error
 	// StopContainer stops a running container with a grace period (i.e., timeout).
 	StopContainer(rawContainerID string, timeout int64) error
-	// RemoveContainer removes the container. If the container is running, the container
-	// should be force removed.
+	// RemoveContainer removes the container.
 	RemoveContainer(rawContainerID string) error
 	// ListContainers lists all containers by filters.
 	ListContainers(filter *runtimeApi.ContainerFilter) ([]*runtimeApi.Container, error)
-	// ContainerStatus returns the container status.
+	// ContainerStatus returns the status of the container.
 	ContainerStatus(rawContainerID string) (*runtimeApi.ContainerStatus, error)
-	// Exec execute a command in the container.
+	// Exec executes a command in the container.
 	Exec(rawContainerID string, cmd []string, tty bool, stdin io.Reader, stdout, stderr io.WriteCloser) error
 }
 
-// ImageManagerService interface defines the interfaces that should be implemented
-// by a container image manager.
-// Thread safety is required from implementations of this interface.
+// ImageManagerService interface should be implemented by a container image
+// manager.
+// The methods should be thread-safe.
 type ImageManagerService interface {
-	// ListImages lists existing images.
+	// ListImages lists the existing images.
 	ListImages(filter *runtimeApi.ImageFilter) ([]*runtimeApi.Image, error)
 	// ImageStatus returns the status of the image.
 	ImageStatus(image *runtimeApi.ImageSpec) (*runtimeApi.Image, error)
-	// PullImage pulls a image with authentication config.
+	// PullImage pulls an image with the authentication config.
 	PullImage(image *runtimeApi.ImageSpec, auth *runtimeApi.AuthConfig) error
 	// RemoveImage removes the image.
 	RemoveImage(image *runtimeApi.ImageSpec) error

pkg/kubelet/dockershim/convert.go

@@ -0,0 +1,91 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+	"strings"
+
+	dockertypes "github.com/docker/engine-api/types"
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+// This file contains helper functions to convert docker API types to runtime
+// API types, or vice versa.
+
+const (
+	// Status of a container returned by docker ListContainers
+	statusRunningPrefix = "Up"
+	statusCreatedPrefix = "Created"
+	statusExitedPrefix  = "Exited"
+)
+
+func toRuntimeAPIImage(image *dockertypes.Image) (*runtimeApi.Image, error) {
+	if image == nil {
+		return nil, fmt.Errorf("unable to convert a nil pointer to a runtime API image")
+	}
+
+	size := uint64(image.VirtualSize)
+	return &runtimeApi.Image{
+		Id:          &image.ID,
+		RepoTags:    image.RepoTags,
+		RepoDigests: image.RepoDigests,
+		Size_:       &size,
+	}, nil
+}
+
+func toRuntimeAPIContainer(c *dockertypes.Container) *runtimeApi.Container {
+	state := toRuntimeAPIContainerState(c.Status)
+	return &runtimeApi.Container{
+		Id:       &c.ID,
+		Name:     &c.Names[0],
+		Image:    &runtimeApi.ImageSpec{Image: &c.Image},
+		ImageRef: &c.ImageID,
+		State:    &state,
+		Labels:   c.Labels,
+	}
+}
+
+func toDockerContainerStatus(state runtimeApi.ContainerState) string {
+	switch state {
+	case runtimeApi.ContainerState_CREATED:
+		return "created"
+	case runtimeApi.ContainerState_RUNNING:
+		return "running"
+	case runtimeApi.ContainerState_EXITED:
+		return "exited"
+	case runtimeApi.ContainerState_UNKNOWN:
+		fallthrough
+	default:
+		return "unknown"
+	}
+}
+
+func toRuntimeAPIContainerState(state string) runtimeApi.ContainerState {
+	// Parse the state string in dockertypes.Container. This could break when
+	// we upgrade docker.
+	switch {
+	case strings.HasPrefix(state, statusRunningPrefix):
+		return runtimeApi.ContainerState_RUNNING
+	case strings.HasPrefix(state, statusExitedPrefix):
+		return runtimeApi.ContainerState_EXITED
+	case strings.HasPrefix(state, statusCreatedPrefix):
+		return runtimeApi.ContainerState_CREATED
+	default:
+		return runtimeApi.ContainerState_UNKNOWN
+	}
+}

pkg/kubelet/dockershim/convert_test.go

@@ -0,0 +1,41 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"testing"
+
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+func TestConvertDockerStatusToRuntimeAPIState(t *testing.T) {
+	testCases := []struct {
+		input    string
+		expected runtimeApi.ContainerState
+	}{
+		{input: "Up 5 hours", expected: runtimeApi.ContainerState_RUNNING},
+		{input: "Exited (0) 2 hours ago", expected: runtimeApi.ContainerState_EXITED},
+		{input: "Created", expected: runtimeApi.ContainerState_CREATED},
+		{input: "Random string", expected: runtimeApi.ContainerState_UNKNOWN},
+	}
+
+	for i, test := range testCases {
+		if actual := toRuntimeAPIContainerState(test.input); actual != test.expected {
+			t.Errorf("Test[%d]: expected %q, got %q", i, test.expected, actual)
+		}
+	}
+}

pkg/kubelet/dockershim/doc.go

@@ -0,0 +1,18 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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.
+*/
+
+// Docker integration using pkg/kubelet/api/v1alpha1/runtime/api.pb.go.
+package dockershim

pkg/kubelet/dockershim/docker_container.go

@@ -0,0 +1,203 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+	"io"
+
+	dockertypes "github.com/docker/engine-api/types"
+	dockercontainer "github.com/docker/engine-api/types/container"
+	dockerfilters "github.com/docker/engine-api/types/filters"
+	dockerstrslice "github.com/docker/engine-api/types/strslice"
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+// ListContainers lists all containers matching the filter.
+func (ds *dockerService) ListContainers(filter *runtimeApi.ContainerFilter) ([]*runtimeApi.Container, error) {
+	opts := dockertypes.ContainerListOptions{All: true}
+
+	opts.Filter = dockerfilters.NewArgs()
+	if filter != nil {
+		if filter.Name != nil {
+			opts.Filter.Add("name", filter.GetName())
+		}
+		if filter.Id != nil {
+			opts.Filter.Add("id", filter.GetId())
+		}
+		if filter.State != nil {
+			opts.Filter.Add("status", toDockerContainerStatus(filter.GetState()))
+		}
+		if filter.PodSandboxId != nil {
+			// TODO: implement this after sandbox functions are implemented.
+		}
+
+		if filter.LabelSelector != nil {
+			for k, v := range filter.LabelSelector {
+				opts.Filter.Add("label", fmt.Sprintf("%s=%s", k, v))
+			}
+		}
+	}
+	containers, err := ds.client.ListContainers(opts)
+	if err != nil {
+		return nil, err
+	}
+	// Convert docker to runtime api containers.
+	result := []*runtimeApi.Container{}
+	for _, c := range containers {
+		result = append(result, toRuntimeAPIContainer(&c))
+	}
+	return result, nil
+}
+
+// CreateContainer creates a new container in the given PodSandbox
+// Note: docker doesn't use LogPath yet.
+// TODO: check if the default values returned by the runtime API are ok.
+func (ds *dockerService) CreateContainer(podSandboxID string, config *runtimeApi.ContainerConfig, sandboxConfig *runtimeApi.PodSandboxConfig) (string, error) {
+	if config == nil {
+		return "", fmt.Errorf("container config is nil")
+	}
+	if sandboxConfig == nil {
+		return "", fmt.Errorf("sandbox config is nil for container %q", config.GetName())
+	}
+
+	// Merge annotations and labels because docker supports only labels.
+	// TODO: add a prefix to annotations so that we can distinguish labels and
+	// annotations when reading back them from the docker container.
+	// TODO: should we apply docker-specific labels?
+	labels := config.GetLabels()
+	for k, v := range config.GetAnnotations() {
+		if _, ok := labels[k]; !ok {
+			// Only write to labels if the key doesn't exist.
+			labels[k] = v
+		}
+	}
+
+	image := ""
+	if iSpec := config.GetImage(); iSpec != nil {
+		image = iSpec.GetImage()
+	}
+	createConfig := dockertypes.ContainerCreateConfig{
+		Name: config.GetName(),
+		Config: &dockercontainer.Config{
+			// TODO: set User.
+			Hostname:   sandboxConfig.GetHostname(),
+			Entrypoint: dockerstrslice.StrSlice(config.GetCommand()),
+			Cmd:        dockerstrslice.StrSlice(config.GetArgs()),
+			Env:        generateEnvList(config.GetEnvs()),
+			Image:      image,
+			WorkingDir: config.GetWorkingDir(),
+			Labels:     labels,
+			// Interactive containers:
+			OpenStdin: config.GetStdin(),
+			StdinOnce: config.GetStdinOnce(),
+			Tty:       config.GetTty(),
+		},
+	}
+
+	// Fill the HostConfig.
+	hc := &dockercontainer.HostConfig{
+		Binds:          generateMountBindings(config.GetMounts()),
+		ReadonlyRootfs: config.GetReadonlyRootfs(),
+		Privileged:     config.GetPrivileged(),
+	}
+
+	// Apply options derived from the sandbox config.
+	if lc := sandboxConfig.GetLinux(); lc != nil {
+		// Apply Cgroup options.
+		// TODO: Check if this works with per-pod cgroups.
+		hc.CgroupParent = lc.GetCgroupParent()
+
+		// Apply namespace options.
+		sandboxNSMode := fmt.Sprintf("container:%v", podSandboxID)
+		hc.NetworkMode = dockercontainer.NetworkMode(sandboxNSMode)
+		hc.IpcMode = dockercontainer.IpcMode(sandboxNSMode)
+		hc.UTSMode = ""
+		hc.PidMode = ""
+
+		nsOpts := lc.GetNamespaceOptions()
+		if nsOpts != nil {
+			if nsOpts.GetHostNetwork() {
+				hc.UTSMode = namespaceModeHost
+			}
+			if nsOpts.GetHostPid() {
+				hc.PidMode = namespaceModeHost
+			}
+		}
+	}
+
+	// Apply Linux-specific options if applicable.
+	if lc := config.GetLinux(); lc != nil {
+		// Apply resource options.
+		// TODO: Check if the units are correct.
+		// TODO: Can we assume the defaults are sane?
+		rOpts := lc.GetResources()
+		if rOpts != nil {
+			hc.Resources = dockercontainer.Resources{
+				Memory:     rOpts.GetMemoryLimitInBytes(),
+				MemorySwap: -1, // Always disable memory swap.
+				CPUShares:  rOpts.GetCpuShares(),
+				CPUQuota:   rOpts.GetCpuQuota(),
+				CPUPeriod:  rOpts.GetCpuPeriod(),
+				// TODO: Need to set devices.
+			}
+			hc.OomScoreAdj = int(rOpts.GetOomScoreAdj())
+		}
+		// Note: ShmSize is handled in kube_docker_client.go
+	}
+
+	// TODO: Seccomp support. Need to figure out how to pass seccomp options
+	// through the runtime API (annotations?).See dockerManager.getSecurityOpts()
+	// for the details. Always set the default seccomp profile for now.
+	hc.SecurityOpt = []string{fmt.Sprintf("%s=%s", "seccomp", defaultSeccompProfile)}
+	// TODO: Add or drop capabilities.
+
+	createConfig.HostConfig = hc
+	createResp, err := ds.client.CreateContainer(createConfig)
+	if createResp != nil {
+		return createResp.ID, err
+	}
+	return "", err
+}
+
+// StartContainer starts the container.
+func (ds *dockerService) StartContainer(rawContainerID string) error {
+	return ds.client.StartContainer(rawContainerID)
+}
+
+// StopContainer stops a running container with a grace period (i.e., timeout).
+func (ds *dockerService) StopContainer(rawContainerID string, timeout int64) error {
+	return ds.client.StopContainer(rawContainerID, int(timeout))
+}
+
+// RemoveContainer removes the container.
+// TODO: If a container is still running, should we forcibly remove it?
+func (ds *dockerService) RemoveContainer(rawContainerID string) error {
+	return ds.client.RemoveContainer(rawContainerID, dockertypes.ContainerRemoveOptions{RemoveVolumes: true})
+}
+
+// ContainerStatus returns the container status.
+// TODO: Implement the function.
+func (ds *dockerService) ContainerStatus(rawContainerID string) (*runtimeApi.ContainerStatus, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+
+// Exec execute a command in the container.
+// TODO: Implement the function.
+func (ds *dockerService) Exec(rawContainerID string, cmd []string, tty bool, stdin io.Reader, stdout, stderr io.WriteCloser) error {
+	return fmt.Errorf("not implemented")
+}

pkg/kubelet/dockershim/docker_image.go

@@ -0,0 +1,85 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+
+	dockertypes "github.com/docker/engine-api/types"
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+// This file implements methods in ImageManagerService.
+
+// ListImages lists existing images.
+func (ds *dockerService) ListImages(filter *runtimeApi.ImageFilter) ([]*runtimeApi.Image, error) {
+	opts := dockertypes.ImageListOptions{}
+	if filter != nil {
+		if imgSpec := filter.GetImage(); imgSpec != nil {
+			opts.MatchName = imgSpec.GetImage()
+		}
+	}
+
+	images, err := ds.client.ListImages(opts)
+	if err != nil {
+		return nil, err
+	}
+
+	result := []*runtimeApi.Image{}
+	for _, i := range images {
+		apiImage, err := toRuntimeAPIImage(&i)
+		if err != nil {
+			// TODO: log an error message?
+			continue
+		}
+		result = append(result, apiImage)
+	}
+	return result, nil
+}
+
+// ImageStatus returns the status of the image.
+func (ds *dockerService) ImageStatus(image *runtimeApi.ImageSpec) (*runtimeApi.Image, error) {
+	images, err := ds.ListImages(&runtimeApi.ImageFilter{Image: image})
+	if err != nil {
+		return nil, err
+	}
+	if len(images) != 1 {
+		return nil, fmt.Errorf("ImageStatus returned more than one image: %+v", images)
+	}
+	return images[0], nil
+}
+
+// PullImage pulls a image with authentication config.
+func (ds *dockerService) PullImage(image *runtimeApi.ImageSpec, auth *runtimeApi.AuthConfig) error {
+	// TODO: add default tags for images or should this be done by kubelet?
+	return ds.client.PullImage(image.GetImage(),
+		dockertypes.AuthConfig{
+			Username:      auth.GetUsername(),
+			Password:      auth.GetPassword(),
+			ServerAddress: auth.GetServerAddress(),
+			IdentityToken: auth.GetIdentityToken(),
+			RegistryToken: auth.GetRegistryToken(),
+		},
+		dockertypes.ImagePullOptions{},
+	)
+}
+
+// RemoveImage removes the image.
+func (ds *dockerService) RemoveImage(image *runtimeApi.ImageSpec) error {
+	_, err := ds.client.RemoveImage(image.GetImage(), dockertypes.ImageRemoveOptions{PruneChildren: true})
+	return err
+}

pkg/kubelet/dockershim/docker_sandbox.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+// CreatePodSandbox creates a pod-level sandbox.
+// The definition of PodSandbox is at https://github.com/kubernetes/kubernetes/pull/25899
+func (ds *dockerService) CreatePodSandbox(config *runtimeApi.PodSandboxConfig) (string, error) {
+	return "", fmt.Errorf("Not implemented")
+}
+
+// StopPodSandbox stops the sandbox. If there are any running containers in the
+// sandbox, they should be force terminated.
+func (ds *dockerService) StopPodSandbox(podSandboxID string) error {
+	return fmt.Errorf("Not implemented")
+}
+
+// DeletePodSandbox deletes the sandbox. If there are running containers in the
+// sandbox, they should be forcibly deleted.
+func (ds *dockerService) DeletePodSandbox(podSandboxID string) error {
+	return fmt.Errorf("Not implemented")
+}
+
+// PodSandboxStatus returns the Status of the PodSandbox.
+func (ds *dockerService) PodSandboxStatus(podSandboxID string) (*runtimeApi.PodSandboxStatus, error) {
+	return nil, fmt.Errorf("Not implemented")
+}
+
+// ListPodSandbox returns a list of Sandbox.
+func (ds *dockerService) ListPodSandbox(filter *runtimeApi.PodSandboxFilter) ([]*runtimeApi.PodSandbox, error) {
+	return nil, fmt.Errorf("Not implemented")
+}

pkg/kubelet/dockershim/docker_service.go

@@ -0,0 +1,78 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+	"io"
+
+	"k8s.io/kubernetes/pkg/api"
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/kubelet/dockertools"
+)
+
+const (
+	dockerRuntimeName = "docker"
+	kubeAPIVersion    = "0.1.0"
+
+	// String used to detect docker host mode for various namespaces (e.g.
+	// networking). Must match the value returned by docker inspect -f
+	// '{{.HostConfig.NetworkMode}}'.
+	namespaceModeHost = "host"
+
+	defaultSeccompProfile = "unconfined"
+)
+
+func NewDockerSevice(client dockertools.DockerInterface) DockerLegacyService {
+	return &dockerService{
+		client: dockertools.NewInstrumentedDockerInterface(client),
+	}
+}
+
+// DockerLegacyService is an interface that embeds both the new
+// RuntimeService and ImageService interfaces, while including legacy methods
+// for backward compatibility.
+type DockerLegacyService interface {
+	kubecontainer.RuntimeService
+	kubecontainer.ImageManagerService
+
+	// Supporting legacy methods for docker.
+	GetContainerLogs(pod *api.Pod, containerID kubecontainer.ContainerID, logOptions *api.PodLogOptions, stdout, stderr io.Writer) (err error)
+	kubecontainer.ContainerAttacher
+	PortForward(pod *kubecontainer.Pod, port uint16, stream io.ReadWriteCloser) error
+}
+
+type dockerService struct {
+	client dockertools.DockerInterface
+}
+
+// Version returns the runtime name, runtime version and runtime API version
+func (ds *dockerService) Version(apiVersion string) (*runtimeApi.VersionResponse, error) {
+	v, err := ds.client.Version()
+	if err != nil {
+		return nil, fmt.Errorf("docker: failed to get docker version: %v", err)
+	}
+	runtimeAPIVersion := kubeAPIVersion
+	name := dockerRuntimeName
+	return &runtimeApi.VersionResponse{
+		Version:           &runtimeAPIVersion,
+		RuntimeName:       &name,
+		RuntimeVersion:    &v.Version,
+		RuntimeApiVersion: &v.APIVersion,
+	}, nil
+}

pkg/kubelet/dockershim/helpers.go

@@ -0,0 +1,78 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+
+	dockerapiversion "github.com/docker/engine-api/types/versions"
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+// apiVersion implements kubecontainer.Version interface by implementing
+// Compare() and String(). It uses the compare function of engine-api to
+// compare docker apiversions.
+type apiVersion string
+
+func (v apiVersion) String() string {
+	return string(v)
+}
+
+func (v apiVersion) Compare(other string) (int, error) {
+	if dockerapiversion.LessThan(string(v), other) {
+		return -1, nil
+	} else if dockerapiversion.GreaterThan(string(v), other) {
+		return 1, nil
+	}
+	return 0, nil
+}
+
+// generateEnvList converts KeyValue list to a list of strings, in the form of
+// '<key>=<value>', which can be understood by docker.
+func generateEnvList(envs []*runtimeApi.KeyValue) (result []string) {
+	for _, env := range envs {
+		result = append(result, fmt.Sprintf("%s=%s", env.GetKey(), env.GetValue()))
+	}
+	return
+}
+
+// generateMountBindings converts the mount list to a list of strings that
+// can be understood by docker.
+// Each element in the string is in the form of:
+// '<HostPath>:<ContainerPath>', or
+// '<HostPath>:<ContainerPath>:ro', if the path is read only, or
+// '<HostPath>:<ContainerPath>:Z', if the volume requires SELinux
+// relabeling and the pod provides an SELinux label
+func generateMountBindings(mounts []*runtimeApi.Mount) (result []string) {
+	// TODO: resolve podHasSELinuxLabel
+	for _, m := range mounts {
+		bind := fmt.Sprintf("%s:%s", m.GetHostPath(), m.GetContainerPath())
+		readOnly := m.GetReadonly()
+		if readOnly {
+			bind += ":ro"
+		}
+		if m.GetSelinuxRelabel() {
+			if readOnly {
+				bind += ",Z"
+			} else {
+				bind += ":Z"
+			}
+		}
+		result = append(result, bind)
+	}
+	return
+}

pkg/kubelet/dockershim/legacy.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+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 dockershim
+
+import (
+	"fmt"
+	"io"
+
+	"k8s.io/kubernetes/pkg/api"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/util/term"
+)
+
+// This file implements the functions that are needed for backward
+// compatibility. Therefore, it imports various kubernetes packages
+// directly.
+
+// TODO: implement the methods in this file.
+func (ds *dockerService) AttachContainer(id kubecontainer.ContainerID, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool, resize <-chan term.Size) (err error) {
+	return fmt.Errorf("not implemented")
+}
+
+func (ds *dockerService) GetContainerLogs(pod *api.Pod, containerID kubecontainer.ContainerID, logOptions *api.PodLogOptions, stdout, stderr io.Writer) (err error) {
+	return fmt.Errorf("not implemented")
+}
+
+func (ds *dockerService) PortForward(pod *kubecontainer.Pod, port uint16, stream io.ReadWriteCloser) error {
+	return fmt.Errorf("not implemented")
+}

pkg/kubelet/dockertools/docker_manager.go

@@ -225,7 +225,7 @@ func NewDockerManager(
 	seccompProfileRoot string,
 	options ...kubecontainer.Option) *DockerManager {
 	// Wrap the docker client with instrumentedDockerInterface
-	client = newInstrumentedDockerInterface(client)
+	client = NewInstrumentedDockerInterface(client)
 
 	// Work out the location of the Docker runtime, defaulting to /var/lib/docker
 	// if there are any problems.

pkg/kubelet/dockertools/instrumented_docker.go

@@ -30,7 +30,7 @@ type instrumentedDockerInterface struct {
 }
 
 // Creates an instrumented DockerInterface from an existing DockerInterface.
-func newInstrumentedDockerInterface(dockerClient DockerInterface) DockerInterface {
+func NewInstrumentedDockerInterface(dockerClient DockerInterface) DockerInterface {
 	return instrumentedDockerInterface{
 		client: dockerClient,
 	}