Add support for Attach to the kubelet.

This is a pre-cursor to supporting 'kubectl attach ...' and 'kubectl run -it ...'

pkg/kubelet/dockertools/docker.go

@@ -71,6 +71,7 @@ type DockerInterface interface {
 	CreateExec(docker.CreateExecOptions) (*docker.Exec, error)
 	StartExec(string, docker.StartExecOptions) error
 	InspectExec(id string) (*docker.ExecInspect, error)
+	AttachToContainer(opts docker.AttachToContainerOptions) error
 }
 
 // KubeletContainerName encapsulates a pod name and a Kubernetes container name.

pkg/kubelet/dockertools/fake_docker_client.go

@@ -298,6 +298,13 @@ func (f *FakeDockerClient) StartExec(_ string, _ docker.StartExecOptions) error
 	return nil
 }
 
+func (f *FakeDockerClient) AttachToContainer(opts docker.AttachToContainerOptions) error {
+	f.Lock()
+	defer f.Unlock()
+	f.called = append(f.called, "attach")
+	return nil
+}
+
 func (f *FakeDockerClient) InspectExec(id string) (*docker.ExecInspect, error) {
 	return f.ExecInspect, f.popError("inspect_exec")
 }

pkg/kubelet/dockertools/instrumented_docker.go

@@ -189,3 +189,12 @@ func (in instrumentedDockerInterface) InspectExec(id string) (*docker.ExecInspec
 	recordError(operation, err)
 	return out, err
 }
+
+func (in instrumentedDockerInterface) AttachToContainer(opts docker.AttachToContainerOptions) error {
+	const operation = "attach"
+	defer recordOperation(operation, time.Now())
+
+	err := in.client.AttachToContainer(opts)
+	recordError(operation, err)
+	return err
+}

pkg/kubelet/dockertools/manager.go

@@ -1006,6 +1006,21 @@ func (dm *DockerManager) ExecInContainer(containerId string, cmd []string, stdin
 	return dm.execHandler.ExecInContainer(dm.client, container, cmd, stdin, stdout, stderr, tty)
 }
 
+func (dm *DockerManager) AttachContainer(containerId string, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool) error {
+	opts := docker.AttachToContainerOptions{
+		Container:    containerId,
+		InputStream:  stdin,
+		OutputStream: stdout,
+		ErrorStream:  stderr,
+		Logs:         true,
+		Stdin:        stdin != nil,
+		Stdout:       stdout != nil,
+		Stderr:       stderr != nil,
+		RawTerminal:  tty,
+	}
+	return dm.client.AttachToContainer(opts)
+}
+
 func noPodInfraContainerError(podName, podNamespace string) error {
 	return fmt.Errorf("cannot find pod infra container in pod %q", kubecontainer.BuildPodFullName(podName, podNamespace))
 }