func postContainersStart(eng *engine.Engine, version version.Version, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	if vars == nil {
		return fmt.Errorf("Missing parameter")
	}
	var (
		name = vars["name"]
		job  = eng.Job("start", name)
	)

	// allow a nil body for backwards compatibility
	if r.Body != nil {
		if api.MatchesContentType(r.Header.Get("Content-Type"), "application/json") {
			if err := job.DecodeEnv(r.Body); err != nil {
				return err
			}
		}
	}
	if err := job.Run(); err != nil {
		if err.Error() == "Container already started" {
			w.WriteHeader(http.StatusNotModified)
			return nil
		}
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (cli *DockerCli) streamHelper(method, path string, setRawTerminal bool, in io.Reader, stdout, stderr io.Writer, headers map[string][]string) error {
	if (method == "POST" || method == "PUT") && in == nil {
		in = bytes.NewReader([]byte{})
	}

	req, err := http.NewRequest(method, fmt.Sprintf("http://v%s%s", api.APIVERSION, path), in)
	if err != nil {
		return err
	}
	req.Header.Set("User-Agent", "Docker-Client/"+dockerversion.VERSION)
	req.URL.Host = cli.addr
	req.URL.Scheme = cli.scheme
	if method == "POST" {
		req.Header.Set("Content-Type", "plain/text")
	}

	if headers != nil {
		for k, v := range headers {
			req.Header[k] = v
		}
	}
	resp, err := cli.HTTPClient().Do(req)
	if err != nil {
		if strings.Contains(err.Error(), "connection refused") {
			return fmt.Errorf("Cannot connect to the Docker daemon. Is 'docker -d' running on this host?")
		}
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return err
		}
		if len(body) == 0 {
			return fmt.Errorf("Error :%s", http.StatusText(resp.StatusCode))
		}
		return fmt.Errorf("Error: %s", bytes.TrimSpace(body))
	}

	if api.MatchesContentType(resp.Header.Get("Content-Type"), "application/json") {
		return utils.DisplayJSONMessagesStream(resp.Body, stdout, cli.terminalFd, cli.isTerminal)
	}
	if stdout != nil || stderr != nil {
		// When TTY is ON, use regular copy
		if setRawTerminal {
			_, err = io.Copy(stdout, resp.Body)
		} else {
			_, err = utils.StdCopy(stdout, stderr, resp.Body)
		}
		utils.Debugf("[stream] End of stdout")
		return err
	}
	return nil
}

func postContainersCopy(eng *engine.Engine, version version.Version, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	if vars == nil {
		return fmt.Errorf("Missing parameter")
	}

	var copyData engine.Env

	if contentType := r.Header.Get("Content-Type"); api.MatchesContentType(contentType, "application/json") {
		if err := copyData.Decode(r.Body); err != nil {
			return err
		}
	} else {
		return fmt.Errorf("Content-Type not supported: %s", contentType)
	}

	if copyData.Get("Resource") == "" {
		return fmt.Errorf("Path cannot be empty")
	}

	origResource := copyData.Get("Resource")

	if copyData.Get("Resource")[0] == '/' {
		copyData.Set("Resource", copyData.Get("Resource")[1:])
	}

	job := eng.Job("container_copy", vars["name"], copyData.Get("Resource"))
	job.Stdout.Add(w)
	if err := job.Run(); err != nil {
		utils.Errorf("%s", err.Error())
		if strings.Contains(err.Error(), "No such container") {
			w.WriteHeader(http.StatusNotFound)
		} else if strings.Contains(err.Error(), "no such file or directory") {
			return fmt.Errorf("Could not find the file %s in container %s", origResource, vars["name"])
		}
	}
	return nil
}

func (cli *DockerCli) stream(method, path string, in io.Reader, out io.Writer, headers map[string][]string) error {
	if (method == "POST" || method == "PUT") && in == nil {
		in = bytes.NewReader([]byte{})
	}

	// fixme: refactor client to support redirect
	re := regexp.MustCompile("/+")
	path = re.ReplaceAllString(path, "/")

	req, err := http.NewRequest(method, fmt.Sprintf("/v%s%s", api.APIVERSION, path), in)
	if err != nil {
		return err
	}
	req.Header.Set("User-Agent", "Docker-Client/"+dockerversion.VERSION)
	req.Host = cli.addr
	if method == "POST" {
		req.Header.Set("Content-Type", "plain/text")
	}

	if headers != nil {
		for k, v := range headers {
			req.Header[k] = v
		}
	}

	dial, err := cli.dial()
	if err != nil {
		if strings.Contains(err.Error(), "connection refused") {
			return fmt.Errorf("Cannot connect to the Docker daemon. Is 'docker -d' running on this host?")
		}
		return err
	}
	clientconn := httputil.NewClientConn(dial, nil)
	resp, err := clientconn.Do(req)
	defer clientconn.Close()
	if err != nil {
		if strings.Contains(err.Error(), "connection refused") {
			return fmt.Errorf("Cannot connect to the Docker daemon. Is 'docker -d' running on this host?")
		}
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return err
		}
		if len(body) == 0 {
			return fmt.Errorf("Error :%s", http.StatusText(resp.StatusCode))
		}
		return fmt.Errorf("Error: %s", bytes.TrimSpace(body))
	}

	if api.MatchesContentType(resp.Header.Get("Content-Type"), "application/json") {
		return utils.DisplayJSONMessagesStream(resp.Body, out, cli.terminalFd, cli.isTerminal)
	}
	if _, err := io.Copy(out, resp.Body); err != nil {
		return err
	}
	return nil
}