Add ability to signal container not just processes

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

api/v1/server.go

@@ -61,6 +61,9 @@ func (s *server) updateContainer(w http.ResponseWriter, r *http.Request) {
 	}
 	e := containerd.NewEvent(containerd.UpdateContainerEventType)
 	e.ID = id
+	if state.Signal != 0 {
+		e.Signal = syscall.Signal(state.Signal)
+	}
 	e.State = &runtime.State{
 		Status: runtime.Status(string(state.Status)),
 	}

api/v1/types.go

@@ -19,6 +19,7 @@ type Machine struct {
 
 type ContainerState struct {
 	Status Status `json:"status,omitempty"`
+	Signal int    `json:"signal,omitempty"`
 }
 
 type Container struct {

linux/linux.go

@@ -225,7 +225,14 @@ func (c *libcontainerContainer) getCheckpointPath(name string) string {
 
 func (c *libcontainerContainer) Checkpoint(cp runtime.Checkpoint) error {
 	opts := c.createCheckpointOpts(cp)
-	if err := os.MkdirAll(opts.ImagesDirectory, 0755); err != nil {
+	if err := os.MkdirAll(filepath.Dir(opts.ImagesDirectory), 0755); err != nil {
+		return err
+	}
+	// mkdir is atomic so if it already exists we can fail
+	if err := os.Mkdir(opts.ImagesDirectory, 0755); err != nil {
+		if os.IsExist(err) {
+			return runtime.ErrCheckpointExists
+		}
 		return err
 	}
 	if err := c.c.Checkpoint(opts); err != nil {

runtime/runtime.go

@@ -10,6 +10,7 @@ var (
 	ErrNotChildProcess      = errors.New("containerd: not a child process for container")
 	ErrInvalidContainerType = errors.New("containerd: invalid container type for runtime")
 	ErrCheckpointNotExists  = errors.New("containerd: checkpoint does not exist for container")
+	ErrCheckpointExists     = errors.New("containerd: checkpoint already exists")
 )
 
 // runtime handles containers, containers handle their own actions.

update.go

@@ -25,5 +25,16 @@ func (h *UpdateEvent) Handle(e *Event) error {
 			return ErrUnknownContainerStatus
 		}
 	}
+	if e.Signal != nil {
+		// signal the pid1/main process of the container
+		processes, err := container.Processes()
+		if err != nil {
+			return err
+		}
+		if len(processes) == 0 {
+			return ErrProcessNotFound
+		}
+		return processes[0].Signal(e.Signal)
+	}
 	return nil
 }