func (s *containerRouter) postContainersStart(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	// If contentLength is -1, we can assumed chunked encoding
	// or more technically that the length is unknown
	// https://golang.org/src/pkg/net/http/request.go#L139
	// net/http otherwise seems to swallow any headers related to chunked encoding
	// including r.TransferEncoding
	// allow a nil body for backwards compatibility

	version := httputils.VersionFromContext(ctx)
	var hostConfig *container.HostConfig
	// A non-nil json object is at least 7 characters.
	if r.ContentLength > 7 || r.ContentLength == -1 {
		if versions.GreaterThanOrEqualTo(version, "1.24") {
			return validationError{fmt.Errorf("starting container with non-empty request body was deprecated since v1.10 and removed in v1.12")}
		}

		if err := httputils.CheckForJSON(r); err != nil {
			return err
		}

		c, err := s.decoder.DecodeHostConfig(r.Body)
		if err != nil {
			return err
		}
		hostConfig = c
	}

	validateHostname := versions.GreaterThanOrEqualTo(version, "1.24")
	if err := s.backend.ContainerStart(vars["name"], hostConfig, validateHostname); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (s *containerRouter) postContainersKill(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	if err := httputils.ParseForm(r); err != nil {
		return err
	}

	var sig syscall.Signal
	name := vars["name"]

	// If we have a signal, look at it. Otherwise, do nothing
	if sigStr := r.Form.Get("signal"); sigStr != "" {
		var err error
		if sig, err = signal.ParseSignal(sigStr); err != nil {
			return err
		}
	}

	if err := s.backend.ContainerKill(name, uint64(sig)); err != nil {
		var isStopped bool
		if e, ok := err.(errContainerIsRunning); ok {
			isStopped = !e.ContainerIsRunning()
		}

		// Return error that's not caused because the container is stopped.
		// Return error if the container is not running and the api is >= 1.20
		// to keep backwards compatibility.
		version := httputils.VersionFromContext(ctx)
		if versions.GreaterThanOrEqualTo(version, "1.20") || !isStopped {
			return fmt.Errorf("Cannot kill container %s: %v", name, err)
		}
	}

	w.WriteHeader(http.StatusNoContent)
	return nil
}

func (c *containerAdapter) create(ctx context.Context) error {
	var cr types.ContainerCreateResponse
	var err error
	version := httputils.VersionFromContext(ctx)
	validateHostname := versions.GreaterThanOrEqualTo(version, "1.24")

	if cr, err = c.backend.CreateManagedContainer(types.ContainerCreateConfig{
		Name:       c.container.name(),
		Config:     c.container.config(),
		HostConfig: c.container.hostConfig(),
		// Use the first network in container create
		NetworkingConfig: c.container.createNetworkingConfig(),
	}, validateHostname); err != nil {
		return err
	}

	// Docker daemon currently doesn't support multiple networks in container create
	// Connect to all other networks
	nc := c.container.connectNetworkingConfig()

	if nc != nil {
		for n, ep := range nc.EndpointsConfig {
			if err := c.backend.ConnectContainerToNetwork(cr.ID, n, ep); err != nil {
				return err
			}
		}
	}

	if err := c.backend.UpdateContainerServiceConfig(cr.ID, c.container.serviceConfig()); err != nil {
		return err
	}

	return nil
}

func (s *containerRouter) postContainersCreate(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	if err := httputils.ParseForm(r); err != nil {
		return err
	}
	if err := httputils.CheckForJSON(r); err != nil {
		return err
	}

	name := r.Form.Get("name")

	config, hostConfig, networkingConfig, err := s.decoder.DecodeConfig(r.Body)
	if err != nil {
		return err
	}
	version := httputils.VersionFromContext(ctx)
	adjustCPUShares := versions.LessThan(version, "1.19")

	validateHostname := versions.GreaterThanOrEqualTo(version, "1.24")
	ccr, err := s.backend.ContainerCreate(types.ContainerCreateConfig{
		Name:             name,
		Config:           config,
		HostConfig:       hostConfig,
		NetworkingConfig: networkingConfig,
		AdjustCPUShares:  adjustCPUShares,
	}, validateHostname)
	if err != nil {
		return err
	}

	return httputils.WriteJSON(w, http.StatusCreated, ccr)
}

func (s *containerRouter) postContainerUpdate(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	if err := httputils.ParseForm(r); err != nil {
		return err
	}
	if err := httputils.CheckForJSON(r); err != nil {
		return err
	}

	version := httputils.VersionFromContext(ctx)
	var updateConfig container.UpdateConfig

	decoder := json.NewDecoder(r.Body)
	if err := decoder.Decode(&updateConfig); err != nil {
		return err
	}

	hostConfig := &container.HostConfig{
		Resources:     updateConfig.Resources,
		RestartPolicy: updateConfig.RestartPolicy,
	}

	name := vars["name"]
	validateHostname := versions.GreaterThanOrEqualTo(version, "1.24")
	resp, err := s.backend.ContainerUpdate(name, hostConfig, validateHostname)
	if err != nil {
		return err
	}

	return httputils.WriteJSON(w, http.StatusOK, resp)
}

func (s *imageRouter) postCommit(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	if err := httputils.ParseForm(r); err != nil {
		return err
	}

	if err := httputils.CheckForJSON(r); err != nil {
		return err
	}

	cname := r.Form.Get("container")

	pause := httputils.BoolValue(r, "pause")
	version := httputils.VersionFromContext(ctx)
	if r.FormValue("pause") == "" && versions.GreaterThanOrEqualTo(version, "1.13") {
		pause = true
	}

	c, _, _, err := s.decoder.DecodeConfig(r.Body)
	if err != nil && err != io.EOF { //Do not fail if body is empty.
		return err
	}
	if c == nil {
		c = &container.Config{}
	}

	commitCfg := &backend.ContainerCommitConfig{
		ContainerCommitConfig: types.ContainerCommitConfig{
			Pause:        pause,
			Repo:         r.Form.Get("repo"),
			Tag:          r.Form.Get("tag"),
			Author:       r.Form.Get("author"),
			Comment:      r.Form.Get("comment"),
			Config:       c,
			MergeConfigs: true,
		},
		Changes: r.Form["changes"],
	}

	imgID, err := s.backend.Commit(cname, commitCfg)
	if err != nil {
		return err
	}

	return httputils.WriteJSON(w, http.StatusCreated, &types.ContainerCommitResponse{
		ID: string(imgID),
	})
}

// postContainersCopy is deprecated in favor of getContainersArchive.
func (s *containerRouter) postContainersCopy(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
	// Deprecated since 1.8, Errors out since 1.12
	version := httputils.VersionFromContext(ctx)
	if versions.GreaterThanOrEqualTo(version, "1.24") {
		w.WriteHeader(http.StatusNotFound)
		return nil
	}
	if err := httputils.CheckForJSON(r); err != nil {
		return err
	}

	cfg := types.CopyConfig{}
	if err := json.NewDecoder(r.Body).Decode(&cfg); err != nil {
		return err
	}

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

	data, err := s.backend.ContainerCopy(vars["name"], cfg.Resource)
	if err != nil {
		if strings.Contains(strings.ToLower(err.Error()), "no such container") {
			w.WriteHeader(http.StatusNotFound)
			return nil
		}
		if os.IsNotExist(err) {
			return fmt.Errorf("Could not find the file %s in container %s", cfg.Resource, vars["name"])
		}
		return err
	}
	defer data.Close()

	w.Header().Set("Content-Type", "application/x-tar")
	if _, err := io.Copy(w, data); err != nil {
		return err
	}

	return nil
}

func (c *containerAdapter) start(ctx context.Context) error {
	version := httputils.VersionFromContext(ctx)
	validateHostname := versions.GreaterThanOrEqualTo(version, "1.24")
	return c.backend.ContainerStart(c.container.name(), nil, validateHostname)
}

func newImageBuildOptions(ctx context.Context, r *http.Request) (*types.ImageBuildOptions, error) {
	version := httputils.VersionFromContext(ctx)
	options := &types.ImageBuildOptions{}
	if httputils.BoolValue(r, "forcerm") && versions.GreaterThanOrEqualTo(version, "1.12") {
		options.Remove = true
	} else if r.FormValue("rm") == "" && versions.GreaterThanOrEqualTo(version, "1.12") {
		options.Remove = true
	} else {
		options.Remove = httputils.BoolValue(r, "rm")
	}
	if httputils.BoolValue(r, "pull") && versions.GreaterThanOrEqualTo(version, "1.16") {
		options.PullParent = true
	}

	options.Dockerfile = r.FormValue("dockerfile")
	options.SuppressOutput = httputils.BoolValue(r, "q")
	options.NoCache = httputils.BoolValue(r, "nocache")
	options.ForceRemove = httputils.BoolValue(r, "forcerm")
	options.MemorySwap = httputils.Int64ValueOrZero(r, "memswap")
	options.Memory = httputils.Int64ValueOrZero(r, "memory")
	options.CPUShares = httputils.Int64ValueOrZero(r, "cpushares")
	options.CPUPeriod = httputils.Int64ValueOrZero(r, "cpuperiod")
	options.CPUQuota = httputils.Int64ValueOrZero(r, "cpuquota")
	options.CPUSetCPUs = r.FormValue("cpusetcpus")
	options.CPUSetMems = r.FormValue("cpusetmems")
	options.CgroupParent = r.FormValue("cgroupparent")
	options.Tags = r.Form["t"]

	if r.Form.Get("shmsize") != "" {
		shmSize, err := strconv.ParseInt(r.Form.Get("shmsize"), 10, 64)
		if err != nil {
			return nil, err
		}
		options.ShmSize = shmSize
	}

	if i := container.Isolation(r.FormValue("isolation")); i != "" {
		if !container.Isolation.IsValid(i) {
			return nil, fmt.Errorf("Unsupported isolation: %q", i)
		}
		options.Isolation = i
	}

	var buildUlimits = []*units.Ulimit{}
	ulimitsJSON := r.FormValue("ulimits")
	if ulimitsJSON != "" {
		if err := json.NewDecoder(strings.NewReader(ulimitsJSON)).Decode(&buildUlimits); err != nil {
			return nil, err
		}
		options.Ulimits = buildUlimits
	}

	var buildArgs = map[string]string{}
	buildArgsJSON := r.FormValue("buildargs")
	if buildArgsJSON != "" {
		if err := json.NewDecoder(strings.NewReader(buildArgsJSON)).Decode(&buildArgs); err != nil {
			return nil, err
		}
		options.BuildArgs = buildArgs
	}
	var labels = map[string]string{}
	labelsJSON := r.FormValue("labels")
	if labelsJSON != "" {
		if err := json.NewDecoder(strings.NewReader(labelsJSON)).Decode(&labels); err != nil {
			return nil, err
		}
		options.Labels = labels
	}

	return options, nil
}