Implement proper shutdown logic

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

containerd/main.go

@@ -86,8 +86,11 @@ func daemon(stateDir string, concurrency, bufferSize int) error {
 		w := containerd.NewWorker(supervisor, wg)
 		go w.Start()
 	}
-	if err := setSubReaper(); err != nil {
-		return err
+	// only set containerd as the subreaper if it is not an init process
+	if pid := os.Getpid(); pid != 1 {
+		if err := setSubReaper(); err != nil {
+			return err
+		}
 	}
 	// start the signal handler in the background.
 	go startSignalHandler(supervisor, bufferSize)

containerd/reap_linux.go

@@ -34,8 +34,7 @@ func startSignalHandler(supervisor *containerd.Supervisor, bufferSize int) {
 	for s := range signals {
 		switch s {
 		case syscall.SIGTERM, syscall.SIGINT:
-			supervisor.Close()
-			os.Exit(0)
+			supervisor.Stop(signals)
 		case syscall.SIGCHLD:
 			exits, err := reap()
 			if err != nil {
@@ -46,6 +45,8 @@ func startSignalHandler(supervisor *containerd.Supervisor, bufferSize int) {
 			}
 		}
 	}
+	supervisor.Close()
+	os.Exit(0)
 }
 
 func reap() (exits []*containerd.Event, err error) {