rkt: add --nuclear-exit flag

If activated, an exited app will cause the whole pod to exit.

rkt/run.go

@@ -59,6 +59,7 @@ End the image arguments with a lone "---" to resume argument parsing.`,
 	flagInheritEnv   bool
 	flagExplicitEnv  envMap
 	flagInteractive  bool
+	flagNuclearExit  bool
 	flagNoOverlay    bool
 	flagLocal        bool
 	flagPodManifest  string
@@ -91,6 +92,7 @@ func init() {
 	cmdRun.Flags().BoolVar(&flagPrivateUsers, "private-users", false, "Run within user namespaces (experimental).")
 	cmdRun.Flags().Var(&flagExplicitEnv, "set-env", "an environment variable to set for apps in the form name=value")
 	cmdRun.Flags().BoolVar(&flagInteractive, "interactive", false, "run pod interactively. If true, only one image may be supplied.")
+	cmdRun.Flags().BoolVar(&flagNuclearExit, "nuclear-exit", false, "make pod exit if an app exits")
 	cmdRun.Flags().BoolVar(&flagLocal, "local", false, "use only local images (do not discover or download from remote URLs)")
 	cmdRun.Flags().StringVar(&flagPodManifest, "pod-manifest", "", "the path to the pod manifest. If it's non-empty, then only '--private-net', '--no-overlay' and '--interactive' will have effects")
 	cmdRun.Flags().BoolVar(&flagMDSRegister, "mds-register", true, "register pod with metadata service")
@@ -297,6 +299,7 @@ func runRun(cmd *cobra.Command, args []string) (exit int) {
 		PrivateNet:   flagPrivateNet,
 		LockFd:       lfd,
 		Interactive:  flagInteractive,
+		NuclearExit:  flagNuclearExit,
 		MDSRegister:  flagMDSRegister,
 		LocalConfig:  globalFlags.LocalConfigDir,
 	}

stage0/run.go

@@ -69,6 +69,7 @@ type RunConfig struct {
 	PrivateNet  common.PrivateNetList // pod should have its own network stack
 	LockFd      int                   // lock file descriptor
 	Interactive bool                  // whether the pod is interactive or not
+	NuclearExit bool                  // whether the pod should exit if an app exits or not
 	MDSRegister bool                  // whether to register with metadata service or not
 	Apps        schema.AppList        // applications (prepare gets them via Apps)
 	LocalConfig string                // Path to local configuration
@@ -374,6 +375,9 @@ func Run(cfg RunConfig, dir string) {
 	if cfg.Interactive {
 		args = append(args, "--interactive")
 	}
+	if cfg.NuclearExit {
+		args = append(args, "--nuclear-exit")
+	}
 	if len(privateUsers) > 0 {
 		args = append(args, "--private-users="+privateUsers)
 	}

stage1/init/init.go

@@ -128,6 +128,7 @@ var (
 	debug        bool
 	privNet      common.PrivateNetList
 	interactive  bool
+	nuclearExit  bool
 	privateUsers string
 	mdsToken     string
 	localhostIP  net.IP
@@ -138,6 +139,7 @@ func init() {
 	flag.BoolVar(&debug, "debug", false, "Run in debug mode")
 	flag.Var(&privNet, "private-net", "Setup private network")
 	flag.BoolVar(&interactive, "interactive", false, "The pod is interactive")
+	flag.BoolVar(&nuclearExit, "nuclear-exit", false, "The pod should exit if an app exits")
 	flag.StringVar(&privateUsers, "private-users", "", "Run within user namespace. Can be set to [=UIDBASE[:NUIDS]]")
 	flag.StringVar(&mdsToken, "mds-token", "", "MDS auth token")
 	flag.StringVar(&localConfig, "local-config", common.DefaultLocalConfigDir, "Local config path")
@@ -583,7 +585,7 @@ func stage1() int {
 		return 2
 	}
 
-	if err = p.PodToSystemd(interactive, flavor, privateUsers); err != nil {
+	if err = p.PodToSystemd(interactive, nuclearExit, flavor, privateUsers); err != nil {
 		fmt.Fprintf(os.Stderr, "Failed to configure systemd: %v\n", err)
 		return 2
 	}

stage1/init/pod.go

@@ -215,7 +215,7 @@ func (p *Pod) writeAppReaper(appName string) error {
 }
 
 // appToSystemd transforms the provided RuntimeApp+ImageManifest into systemd units
-func (p *Pod) appToSystemd(ra *schema.RuntimeApp, interactive bool, flavor string, privateUsers string) error {
+func (p *Pod) appToSystemd(ra *schema.RuntimeApp, interactive bool, nuclearExit bool, flavor string, privateUsers string) error {
 	app := ra.App
 	appName := ra.Name
 	image, ok := p.Images[appName.String()]
@@ -282,6 +282,10 @@ func (p *Pod) appToSystemd(ra *schema.RuntimeApp, interactive bool, flavor strin
 		opts = append(opts, unit.NewUnitOption("Service", "SyslogIdentifier", filepath.Base(app.Exec[0])))
 	}
 
+	if nuclearExit {
+		opts = append(opts, unit.NewUnitOption("Service", "ExecStop", "/usr/bin/systemctl start halt.target"))
+	}
+
 	for _, eh := range app.EventHandlers {
 		var typ string
 		switch eh.Name {
@@ -426,7 +430,7 @@ func (p *Pod) writeEnvFile(env types.Environment, appName types.ACName, privateU
 
 // PodToSystemd creates the appropriate systemd service unit files for
 // all the constituent apps of the Pod
-func (p *Pod) PodToSystemd(interactive bool, flavor string, privateUsers string) error {
+func (p *Pod) PodToSystemd(interactive bool, nuclearExit bool, flavor string, privateUsers string) error {
 
 	if flavor == "kvm" {
 		// prepare all applications names to become dependency for mount units
@@ -446,7 +450,7 @@ func (p *Pod) PodToSystemd(interactive bool, flavor string, privateUsers string)
 
 	for i := range p.Manifest.Apps {
 		ra := &p.Manifest.Apps[i]
-		if err := p.appToSystemd(ra, interactive, flavor, privateUsers); err != nil {
+		if err := p.appToSystemd(ra, interactive, nuclearExit, flavor, privateUsers); err != nil {
 			return fmt.Errorf("failed to transform app %q into systemd service: %v", ra.Name, err)
 		}
 	}