systemd integration with container runtime for supporting sd_notify protocol

Signed-off-by: Shishir Mahajan <shishir.mahajan@redhat.com>

run.go

@@ -67,6 +67,12 @@ func execContainer(context *cli.Context, spec *specs.LinuxSpec) (int, error) {
 // default action is to execute a container
 func runAction(context *cli.Context) {
 	spec, err := loadSpec(context.Args().First())
+
+	notifySocket := os.Getenv("NOTIFY_SOCKET")
+	if notifySocket != "" {
+		setupSdNotify(spec, notifySocket)
+	}
+
 	if err != nil {
 		fatal(err)
 	}
@@ -82,6 +88,13 @@ func runAction(context *cli.Context) {
 	os.Exit(status)
 }
 
+// If systemd is supporting sd_notify protocol, this function will add support
+// for sd_notify protocol from within the container.
+func setupSdNotify(spec *specs.LinuxSpec, notifySocket string) {
+	spec.Mounts = append(spec.Mounts, specs.Mount{Type: "bind", Source: notifySocket, Destination: notifySocket, Options: "bind"})
+	spec.Process.Env = append(spec.Process.Env, fmt.Sprintf("NOTIFY_SOCKET=%s", notifySocket))
+}
+
 func destroy(container libcontainer.Container) {
 	status, err := container.Status()
 	if err != nil {