Beispiel #1
0
// appToSystemd transforms the provided RuntimeApp+ImageManifest into systemd units
func appToSystemd(p *stage1commontypes.Pod, ra *schema.RuntimeApp, interactive bool, flavor string, privateUsers string) error {
	app := ra.App
	appName := ra.Name
	image, ok := p.Images[appName.String()]
	if !ok {
		// This is impossible as we have updated the map in LoadPod().
		panic(fmt.Sprintf("No images for app %q", ra.Name.String()))
	}
	imgName := image.Name

	if len(app.Exec) == 0 {
		return fmt.Errorf(`image %q has an empty "exec" (try --exec=BINARY)`, imgName)
	}

	workDir := "/"
	if app.WorkingDirectory != "" {
		workDir = app.WorkingDirectory
	}

	env := app.Environment

	env.Set("AC_APP_NAME", appName.String())
	if p.MetadataServiceURL != "" {
		env.Set("AC_METADATA_URL", p.MetadataServiceURL)
	}

	if err := writeEnvFile(p, env, appName, privateUsers); err != nil {
		return fmt.Errorf("unable to write environment file: %v", err)
	}

	// This is a partial implementation for app.User and app.Group:
	// For now, only numeric ids (and the string "root") are supported.
	var uid, gid int
	var err error
	if app.User == "root" {
		uid = 0
	} else {
		uid, err = strconv.Atoi(app.User)
		if err != nil {
			return fmt.Errorf("non-numerical user id not supported yet")
		}
	}
	if app.Group == "root" {
		gid = 0
	} else {
		gid, err = strconv.Atoi(app.Group)
		if err != nil {
			return fmt.Errorf("non-numerical group id not supported yet")
		}
	}

	execWrap := []string{"/appexec", common.RelAppRootfsPath(appName), workDir, RelEnvFilePath(appName), strconv.Itoa(uid), generateGidArg(gid, app.SupplementaryGIDs)}
	execStart := quoteExec(append(execWrap, app.Exec...))
	opts := []*unit.UnitOption{
		unit.NewUnitOption("Unit", "Description", fmt.Sprintf("Application=%v Image=%v", appName, imgName)),
		unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
		unit.NewUnitOption("Unit", "Wants", fmt.Sprintf("reaper-%s.service", appName)),
		unit.NewUnitOption("Service", "Restart", "no"),
		unit.NewUnitOption("Service", "ExecStart", execStart),
		unit.NewUnitOption("Service", "User", "0"),
		unit.NewUnitOption("Service", "Group", "0"),
	}

	if interactive {
		opts = append(opts, unit.NewUnitOption("Service", "StandardInput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "tty"))
	} else {
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "SyslogIdentifier", filepath.Base(app.Exec[0])))
	}

	// When an app fails, we shut down the pod
	opts = append(opts, unit.NewUnitOption("Unit", "OnFailure", "halt.target"))

	for _, eh := range app.EventHandlers {
		var typ string
		switch eh.Name {
		case "pre-start":
			typ = "ExecStartPre"
		case "post-stop":
			typ = "ExecStopPost"
		default:
			return fmt.Errorf("unrecognized eventHandler: %v", eh.Name)
		}
		exec := quoteExec(append(execWrap, eh.Exec...))
		opts = append(opts, unit.NewUnitOption("Service", typ, exec))
	}

	// Some pre-start jobs take a long time, set the timeout to 0
	opts = append(opts, unit.NewUnitOption("Service", "TimeoutStartSec", "0"))

	var saPorts []types.Port
	for _, p := range app.Ports {
		if p.SocketActivated {
			saPorts = append(saPorts, p)
		}
	}

	for _, i := range app.Isolators {
		switch v := i.Value().(type) {
		case *types.ResourceMemory:
			opts, err = cgroup.MaybeAddIsolator(opts, "memory", v.Limit())
			if err != nil {
				return err
			}
		case *types.ResourceCPU:
			opts, err = cgroup.MaybeAddIsolator(opts, "cpu", v.Limit())
			if err != nil {
				return err
			}
		}
	}

	if len(saPorts) > 0 {
		sockopts := []*unit.UnitOption{
			unit.NewUnitOption("Unit", "Description", fmt.Sprintf("Application=%v Image=%v %s", appName, imgName, "socket-activated ports")),
			unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
			unit.NewUnitOption("Socket", "BindIPv6Only", "both"),
			unit.NewUnitOption("Socket", "Service", ServiceUnitName(appName)),
		}

		for _, sap := range saPorts {
			var proto string
			switch sap.Protocol {
			case "tcp":
				proto = "ListenStream"
			case "udp":
				proto = "ListenDatagram"
			default:
				return fmt.Errorf("unrecognized protocol: %v", sap.Protocol)
			}
			sockopts = append(sockopts, unit.NewUnitOption("Socket", proto, fmt.Sprintf("%v", sap.Port)))
		}

		file, err := os.OpenFile(SocketUnitPath(p.Root, appName), os.O_WRONLY|os.O_CREATE, 0644)
		if err != nil {
			return fmt.Errorf("failed to create socket file: %v", err)
		}
		defer file.Close()

		if _, err = io.Copy(file, unit.Serialize(sockopts)); err != nil {
			return fmt.Errorf("failed to write socket unit file: %v", err)
		}

		if err = os.Symlink(path.Join("..", SocketUnitName(appName)), SocketWantPath(p.Root, appName)); err != nil {
			return fmt.Errorf("failed to link socket want: %v", err)
		}

		opts = append(opts, unit.NewUnitOption("Unit", "Requires", SocketUnitName(appName)))
	}

	opts = append(opts, unit.NewUnitOption("Unit", "Requires", InstantiatedPrepareAppUnitName(appName)))
	opts = append(opts, unit.NewUnitOption("Unit", "After", InstantiatedPrepareAppUnitName(appName)))

	file, err := os.OpenFile(ServiceUnitPath(p.Root, appName), os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return fmt.Errorf("failed to create service unit file: %v", err)
	}
	defer file.Close()

	if _, err = io.Copy(file, unit.Serialize(opts)); err != nil {
		return fmt.Errorf("failed to write service unit file: %v", err)
	}

	if err = os.Symlink(path.Join("..", ServiceUnitName(appName)), ServiceWantPath(p.Root, appName)); err != nil {
		return fmt.Errorf("failed to link service want: %v", err)
	}

	if flavor == "kvm" {
		// bind mount all shared volumes from /mnt/volumeName (we don't use mechanism for bind-mounting given by nspawn)
		err := AppToSystemdMountUnits(common.Stage1RootfsPath(p.Root), appName, p.Manifest.Volumes, ra, UnitsDir)
		if err != nil {
			return fmt.Errorf("failed to prepare mount units: %v", err)
		}

	}

	if err = writeAppReaper(p, appName.String()); err != nil {
		return fmt.Errorf("Failed to write app %q reaper service: %v\n", appName, err)
	}

	return nil
}
Beispiel #2
0
// appToSystemd transforms the provided RuntimeApp+ImageManifest into systemd units
func appToSystemd(p *stage1commontypes.Pod, ra *schema.RuntimeApp, interactive bool, flavor string, privateUsers string) error {
	app := ra.App
	appName := ra.Name
	imgName := p.AppNameToImageName(appName)

	if len(app.Exec) == 0 {
		return fmt.Errorf(`image %q has an empty "exec" (try --exec=BINARY)`, imgName)
	}

	workDir := "/"
	if app.WorkingDirectory != "" {
		workDir = app.WorkingDirectory
	}

	env := app.Environment

	env.Set("AC_APP_NAME", appName.String())
	if p.MetadataServiceURL != "" {
		env.Set("AC_METADATA_URL", p.MetadataServiceURL)
	}

	if err := writeEnvFile(p, env, appName, privateUsers); err != nil {
		return errwrap.Wrap(errors.New("unable to write environment file"), err)
	}

	var _uid, gid int
	var err error

	uidRange := uid.NewBlankUidRange()
	if err := uidRange.Deserialize([]byte(privateUsers)); err != nil {
		return errwrap.Wrap(errors.New("unable to deserialize uid range"), err)
	}

	if strings.HasPrefix(app.User, "/") {
		var stat syscall.Stat_t
		if err = syscall.Lstat(filepath.Join(common.AppRootfsPath(p.Root, appName),
			app.User), &stat); err != nil {
			return errwrap.Wrap(fmt.Errorf("unable to get uid from file %q",
				app.User), err)
		}
		uidReal, _, err := uidRange.UnshiftRange(stat.Uid, 0)
		if err != nil {
			return errwrap.Wrap(errors.New("unable to determine real uid"), err)
		}
		_uid = int(uidReal)
	} else {
		_uid, err = strconv.Atoi(app.User)
		if err != nil {
			_uid, err = passwd.LookupUidFromFile(app.User,
				filepath.Join(common.AppRootfsPath(p.Root, appName), "etc/passwd"))
			if err != nil {
				return errwrap.Wrap(fmt.Errorf("cannot lookup user %q", app.User), err)
			}
		}
	}

	if strings.HasPrefix(app.Group, "/") {
		var stat syscall.Stat_t
		if err = syscall.Lstat(filepath.Join(common.AppRootfsPath(p.Root, appName),
			app.Group), &stat); err != nil {
			return errwrap.Wrap(fmt.Errorf("unable to get gid from file %q",
				app.Group), err)
		}
		_, gidReal, err := uidRange.UnshiftRange(0, stat.Gid)
		if err != nil {
			return errwrap.Wrap(errors.New("unable to determine real gid"), err)
		}
		gid = int(gidReal)
	} else {
		gid, err = strconv.Atoi(app.Group)
		if err != nil {
			gid, err = group.LookupGidFromFile(app.Group,
				filepath.Join(common.AppRootfsPath(p.Root, appName), "etc/group"))
			if err != nil {
				return errwrap.Wrap(fmt.Errorf("cannot lookup group %q", app.Group), err)
			}
		}
	}

	execWrap := []string{"/appexec", common.RelAppRootfsPath(appName), workDir, RelEnvFilePath(appName),
		strconv.Itoa(_uid), generateGidArg(gid, app.SupplementaryGIDs), "--"}
	execStart := quoteExec(append(execWrap, app.Exec...))
	opts := []*unit.UnitOption{
		unit.NewUnitOption("Unit", "Description", fmt.Sprintf("Application=%v Image=%v", appName, imgName)),
		unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
		unit.NewUnitOption("Unit", "Wants", fmt.Sprintf("reaper-%s.service", appName)),
		unit.NewUnitOption("Service", "Restart", "no"),
		unit.NewUnitOption("Service", "ExecStart", execStart),
		unit.NewUnitOption("Service", "User", "0"),
		unit.NewUnitOption("Service", "Group", "0"),
	}

	if interactive {
		opts = append(opts, unit.NewUnitOption("Service", "StandardInput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "tty"))
	} else {
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "SyslogIdentifier", filepath.Base(app.Exec[0])))
	}

	// When an app fails, we shut down the pod
	opts = append(opts, unit.NewUnitOption("Unit", "OnFailure", "halt.target"))

	for _, eh := range app.EventHandlers {
		var typ string
		switch eh.Name {
		case "pre-start":
			typ = "ExecStartPre"
		case "post-stop":
			typ = "ExecStopPost"
		default:
			return fmt.Errorf("unrecognized eventHandler: %v", eh.Name)
		}
		exec := quoteExec(append(execWrap, eh.Exec...))
		opts = append(opts, unit.NewUnitOption("Service", typ, exec))
	}

	// Some pre-start jobs take a long time, set the timeout to 0
	opts = append(opts, unit.NewUnitOption("Service", "TimeoutStartSec", "0"))

	var saPorts []types.Port
	for _, p := range app.Ports {
		if p.SocketActivated {
			saPorts = append(saPorts, p)
		}
	}

	for _, i := range app.Isolators {
		switch v := i.Value().(type) {
		case *types.ResourceMemory:
			opts, err = cgroup.MaybeAddIsolator(opts, "memory", v.Limit())
			if err != nil {
				return err
			}
		case *types.ResourceCPU:
			opts, err = cgroup.MaybeAddIsolator(opts, "cpu", v.Limit())
			if err != nil {
				return err
			}
		}
	}

	if len(saPorts) > 0 {
		sockopts := []*unit.UnitOption{
			unit.NewUnitOption("Unit", "Description", fmt.Sprintf("Application=%v Image=%v %s", appName, imgName, "socket-activated ports")),
			unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
			unit.NewUnitOption("Socket", "BindIPv6Only", "both"),
			unit.NewUnitOption("Socket", "Service", ServiceUnitName(appName)),
		}

		for _, sap := range saPorts {
			var proto string
			switch sap.Protocol {
			case "tcp":
				proto = "ListenStream"
			case "udp":
				proto = "ListenDatagram"
			default:
				return fmt.Errorf("unrecognized protocol: %v", sap.Protocol)
			}
			// We find the host port for the pod's port and use that in the
			// socket unit file.
			// This is so because systemd inside the pod will match based on
			// the socket port number, and since the socket was created on the
			// host, it will have the host port number.
			port := findHostPort(*p.Manifest, sap.Name)
			if port == 0 {
				log.Printf("warning: no --port option for socket-activated port %q, assuming port %d as specified in the manifest", sap.Name, sap.Port)
				port = sap.Port
			}
			sockopts = append(sockopts, unit.NewUnitOption("Socket", proto, fmt.Sprintf("%v", port)))
		}

		file, err := os.OpenFile(SocketUnitPath(p.Root, appName), os.O_WRONLY|os.O_CREATE, 0644)
		if err != nil {
			return errwrap.Wrap(errors.New("failed to create socket file"), err)
		}
		defer file.Close()

		if _, err = io.Copy(file, unit.Serialize(sockopts)); err != nil {
			return errwrap.Wrap(errors.New("failed to write socket unit file"), err)
		}

		if err = os.Symlink(path.Join("..", SocketUnitName(appName)), SocketWantPath(p.Root, appName)); err != nil {
			return errwrap.Wrap(errors.New("failed to link socket want"), err)
		}

		opts = append(opts, unit.NewUnitOption("Unit", "Requires", SocketUnitName(appName)))
	}

	opts = append(opts, unit.NewUnitOption("Unit", "Requires", InstantiatedPrepareAppUnitName(appName)))
	opts = append(opts, unit.NewUnitOption("Unit", "After", InstantiatedPrepareAppUnitName(appName)))

	file, err := os.OpenFile(ServiceUnitPath(p.Root, appName), os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return errwrap.Wrap(errors.New("failed to create service unit file"), err)
	}
	defer file.Close()

	if _, err = io.Copy(file, unit.Serialize(opts)); err != nil {
		return errwrap.Wrap(errors.New("failed to write service unit file"), err)
	}

	if err = os.Symlink(path.Join("..", ServiceUnitName(appName)), ServiceWantPath(p.Root, appName)); err != nil {
		return errwrap.Wrap(errors.New("failed to link service want"), err)
	}

	if flavor == "kvm" {
		// bind mount all shared volumes from /mnt/volumeName (we don't use mechanism for bind-mounting given by nspawn)
		err := AppToSystemdMountUnits(common.Stage1RootfsPath(p.Root), appName, p.Manifest.Volumes, ra, UnitsDir)
		if err != nil {
			return errwrap.Wrap(errors.New("failed to prepare mount units"), err)
		}

	}

	if err = writeAppReaper(p, appName.String()); err != nil {
		return errwrap.Wrap(fmt.Errorf("failed to write app %q reaper service", appName), err)
	}

	return nil
}
Beispiel #3
0
// appToSystemd transforms the provided RuntimeApp+ImageManifest into systemd units
func (p *Pod) appToSystemd(ra *schema.RuntimeApp, interactive bool) error {
	name := ra.Name.String()
	id := ra.Image.ID
	app := ra.App

	workDir := "/"
	if app.WorkingDirectory != "" {
		workDir = app.WorkingDirectory
	}

	env := app.Environment
	env.Set("AC_APP_NAME", name)
	env.Set("AC_METADATA_URL", p.MetadataServiceURL)

	if err := p.writeEnvFile(env, id); err != nil {
		return fmt.Errorf("unable to write environment file: %v", err)
	}

	// This is a partial implementation for app.User and app.Group:
	// For now, only numeric ids (and the string "root") are supported.
	var uid, gid int
	var err error
	if app.User == "root" {
		uid = 0
	} else {
		uid, err = strconv.Atoi(app.User)
		if err != nil {
			return fmt.Errorf("non-numerical user id not supported yet")
		}
	}
	if app.Group == "root" {
		gid = 0
	} else {
		gid, err = strconv.Atoi(app.Group)
		if err != nil {
			return fmt.Errorf("non-numerical group id not supported yet")
		}
	}

	execWrap := []string{"/diagexec", common.RelAppRootfsPath(id), workDir, RelEnvFilePath(id), strconv.Itoa(uid), strconv.Itoa(gid)}
	execStart := quoteExec(append(execWrap, app.Exec...))
	opts := []*unit.UnitOption{
		unit.NewUnitOption("Unit", "Description", name),
		unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
		unit.NewUnitOption("Unit", "OnFailure", "reaper.service"),
		unit.NewUnitOption("Unit", "Wants", "exit-watcher.service"),
		unit.NewUnitOption("Service", "Restart", "no"),
		unit.NewUnitOption("Service", "ExecStart", execStart),
		unit.NewUnitOption("Service", "User", "0"),
		unit.NewUnitOption("Service", "Group", "0"),
	}

	_, systemdStage1Version, err := p.getFlavor()
	if err != nil {
		return fmt.Errorf("Failed to get stage1 flavor: %v\n", err)
	}

	if interactive {
		opts = append(opts, unit.NewUnitOption("Service", "StandardInput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "tty"))
	} else if systemdSupportsJournalLinking(systemdStage1Version) {
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "SyslogIdentifier", filepath.Base(app.Exec[0])))
	}

	for _, eh := range app.EventHandlers {
		var typ string
		switch eh.Name {
		case "pre-start":
			typ = "ExecStartPre"
		case "post-stop":
			typ = "ExecStopPost"
		default:
			return fmt.Errorf("unrecognized eventHandler: %v", eh.Name)
		}
		exec := quoteExec(append(execWrap, eh.Exec...))
		opts = append(opts, unit.NewUnitOption("Service", typ, exec))
	}

	saPorts := []types.Port{}
	for _, p := range app.Ports {
		if p.SocketActivated {
			saPorts = append(saPorts, p)
		}
	}

	for _, i := range app.Isolators {
		switch v := i.Value().(type) {
		case *types.ResourceMemory:
			limit := v.Limit().String()
			opts, err = cgroup.MaybeAddIsolator(opts, "memory", limit)
			if err != nil {
				return err
			}
		case *types.ResourceCPU:
			limit := v.Limit().String()
			opts, err = cgroup.MaybeAddIsolator(opts, "cpu", limit)
			if err != nil {
				return err
			}
		}
	}

	if len(saPorts) > 0 {
		sockopts := []*unit.UnitOption{
			unit.NewUnitOption("Unit", "Description", name+" socket-activated ports"),
			unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
			unit.NewUnitOption("Socket", "BindIPv6Only", "both"),
			unit.NewUnitOption("Socket", "Service", ServiceUnitName(id)),
		}

		for _, sap := range saPorts {
			var proto string
			switch sap.Protocol {
			case "tcp":
				proto = "ListenStream"
			case "udp":
				proto = "ListenDatagram"
			default:
				return fmt.Errorf("unrecognized protocol: %v", sap.Protocol)
			}
			sockopts = append(sockopts, unit.NewUnitOption("Socket", proto, fmt.Sprintf("%v", sap.Port)))
		}

		file, err := os.OpenFile(SocketUnitPath(p.Root, id), os.O_WRONLY|os.O_CREATE, 0644)
		if err != nil {
			return fmt.Errorf("failed to create socket file: %v", err)
		}
		defer file.Close()

		if _, err = io.Copy(file, unit.Serialize(sockopts)); err != nil {
			return fmt.Errorf("failed to write socket unit file: %v", err)
		}

		if err = os.Symlink(path.Join("..", SocketUnitName(id)), SocketWantPath(p.Root, id)); err != nil {
			return fmt.Errorf("failed to link socket want: %v", err)
		}

		opts = append(opts, unit.NewUnitOption("Unit", "Requires", SocketUnitName(id)))
	}

	opts = append(opts, unit.NewUnitOption("Unit", "Requires", InstantiatedPrepareAppUnitName(id)))
	opts = append(opts, unit.NewUnitOption("Unit", "After", InstantiatedPrepareAppUnitName(id)))

	file, err := os.OpenFile(ServiceUnitPath(p.Root, id), os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return fmt.Errorf("failed to create service unit file: %v", err)
	}
	defer file.Close()

	if _, err = io.Copy(file, unit.Serialize(opts)); err != nil {
		return fmt.Errorf("failed to write service unit file: %v", err)
	}

	if err = os.Symlink(path.Join("..", ServiceUnitName(id)), ServiceWantPath(p.Root, id)); err != nil {
		return fmt.Errorf("failed to link service want: %v", err)
	}

	return nil
}
Beispiel #4
0
// appToSystemd transforms the provided RuntimeApp+ImageManifest into systemd units
func appToSystemd(p *stage1commontypes.Pod, ra *schema.RuntimeApp, interactive bool, flavor string, privateUsers string) error {
	app := ra.App
	appName := ra.Name
	imgName := p.AppNameToImageName(appName)

	if len(app.Exec) == 0 {
		return fmt.Errorf(`image %q has an empty "exec" (try --exec=BINARY)`, imgName)
	}

	workDir := "/"
	if app.WorkingDirectory != "" {
		workDir = app.WorkingDirectory
	}

	env := app.Environment

	env.Set("AC_APP_NAME", appName.String())
	if p.MetadataServiceURL != "" {
		env.Set("AC_METADATA_URL", p.MetadataServiceURL)
	}

	envFilePath := EnvFilePath(p.Root, appName)

	uidRange := user.NewBlankUidRange()
	if err := uidRange.Deserialize([]byte(privateUsers)); err != nil {
		return err
	}

	if err := writeEnvFile(p, env, appName, uidRange, '\n', envFilePath); err != nil {
		return errwrap.Wrap(errors.New("unable to write environment file for systemd"), err)
	}

	u, g, err := parseUserGroup(p, ra, uidRange)
	if err != nil {
		return err
	}

	if err := generateSysusers(p, ra, u, g, uidRange); err != nil {
		return errwrap.Wrap(errors.New("unable to generate sysusers"), err)
	}

	binPath, err := findBinPath(p, appName, *app, workDir, app.Exec[0])
	if err != nil {
		return err
	}

	var supplementaryGroups []string
	for _, g := range app.SupplementaryGIDs {
		supplementaryGroups = append(supplementaryGroups, strconv.Itoa(g))
	}

	capabilitiesStr, err := getAppCapabilities(app.Isolators)
	if err != nil {
		return err
	}

	noNewPrivileges := getAppNoNewPrivileges(app.Isolators)

	execStart := append([]string{binPath}, app.Exec[1:]...)
	execStartString := quoteExec(execStart)
	opts := []*unit.UnitOption{
		unit.NewUnitOption("Unit", "Description", fmt.Sprintf("Application=%v Image=%v", appName, imgName)),
		unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
		unit.NewUnitOption("Unit", "Wants", fmt.Sprintf("reaper-%s.service", appName)),
		unit.NewUnitOption("Service", "Restart", "no"),
		unit.NewUnitOption("Service", "ExecStart", execStartString),
		unit.NewUnitOption("Service", "RootDirectory", common.RelAppRootfsPath(appName)),
		// MountFlags=shared creates a new mount namespace and (as unintuitive
		// as it might seem) makes sure the mount is slave+shared.
		unit.NewUnitOption("Service", "MountFlags", "shared"),
		unit.NewUnitOption("Service", "WorkingDirectory", workDir),
		unit.NewUnitOption("Service", "EnvironmentFile", RelEnvFilePath(appName)),
		unit.NewUnitOption("Service", "User", strconv.Itoa(u)),
		unit.NewUnitOption("Service", "Group", strconv.Itoa(g)),
		unit.NewUnitOption("Service", "SupplementaryGroups", strings.Join(supplementaryGroups, " ")),
		unit.NewUnitOption("Service", "CapabilityBoundingSet", strings.Join(capabilitiesStr, " ")),
		unit.NewUnitOption("Service", "NoNewPrivileges", strconv.FormatBool(noNewPrivileges)),
		// This helps working around a race
		// (https://github.com/systemd/systemd/issues/2913) that causes the
		// systemd unit name not getting written to the journal if the unit is
		// short-lived and runs as non-root.
		unit.NewUnitOption("Service", "SyslogIdentifier", appName.String()),
	}

	// Restrict access to sensitive paths (eg. procfs)
	opts = protectSystemFiles(opts, appName)

	if ra.ReadOnlyRootFS {
		opts = append(opts, unit.NewUnitOption("Service", "ReadOnlyDirectories", common.RelAppRootfsPath(appName)))
	}

	// TODO(tmrts): Extract this logic into a utility function.
	vols := make(map[types.ACName]types.Volume)
	for _, v := range p.Manifest.Volumes {
		vols[v.Name] = v
	}

	absRoot, err := filepath.Abs(p.Root) // Absolute path to the pod's rootfs.
	if err != nil {
		return err
	}
	appRootfs := common.AppRootfsPath(absRoot, appName)

	rwDirs := []string{}
	imageManifest := p.Images[appName.String()]
	for _, m := range GenerateMounts(ra, vols, imageManifest) {
		mntPath, err := EvaluateSymlinksInsideApp(appRootfs, m.Path)
		if err != nil {
			return err
		}

		if !IsMountReadOnly(vols[m.Volume], app.MountPoints) {
			rwDirs = append(rwDirs, filepath.Join(common.RelAppRootfsPath(appName), mntPath))
		}
	}

	opts = append(opts, unit.NewUnitOption("Service", "ReadWriteDirectories", strings.Join(rwDirs, " ")))

	if interactive {
		opts = append(opts, unit.NewUnitOption("Service", "StandardInput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "tty"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "tty"))
	} else {
		opts = append(opts, unit.NewUnitOption("Service", "StandardOutput", "journal+console"))
		opts = append(opts, unit.NewUnitOption("Service", "StandardError", "journal+console"))
	}

	// When an app fails, we shut down the pod
	opts = append(opts, unit.NewUnitOption("Unit", "OnFailure", "halt.target"))

	for _, eh := range app.EventHandlers {
		var typ string
		switch eh.Name {
		case "pre-start":
			typ = "ExecStartPre"
		case "post-stop":
			typ = "ExecStopPost"
		default:
			return fmt.Errorf("unrecognized eventHandler: %v", eh.Name)
		}
		exec := quoteExec(eh.Exec)
		opts = append(opts, unit.NewUnitOption("Service", typ, exec))
	}

	// Some pre-start jobs take a long time, set the timeout to 0
	opts = append(opts, unit.NewUnitOption("Service", "TimeoutStartSec", "0"))

	var saPorts []types.Port
	for _, p := range app.Ports {
		if p.SocketActivated {
			saPorts = append(saPorts, p)
		}
	}

	for _, i := range app.Isolators {
		switch v := i.Value().(type) {
		case *types.ResourceMemory:
			opts, err = cgroup.MaybeAddIsolator(opts, "memory", v.Limit())
			if err != nil {
				return err
			}
		case *types.ResourceCPU:
			opts, err = cgroup.MaybeAddIsolator(opts, "cpu", v.Limit())
			if err != nil {
				return err
			}
		}
	}

	if len(saPorts) > 0 {
		sockopts := []*unit.UnitOption{
			unit.NewUnitOption("Unit", "Description", fmt.Sprintf("Application=%v Image=%v %s", appName, imgName, "socket-activated ports")),
			unit.NewUnitOption("Unit", "DefaultDependencies", "false"),
			unit.NewUnitOption("Socket", "BindIPv6Only", "both"),
			unit.NewUnitOption("Socket", "Service", ServiceUnitName(appName)),
		}

		for _, sap := range saPorts {
			var proto string
			switch sap.Protocol {
			case "tcp":
				proto = "ListenStream"
			case "udp":
				proto = "ListenDatagram"
			default:
				return fmt.Errorf("unrecognized protocol: %v", sap.Protocol)
			}
			// We find the host port for the pod's port and use that in the
			// socket unit file.
			// This is so because systemd inside the pod will match based on
			// the socket port number, and since the socket was created on the
			// host, it will have the host port number.
			port := findHostPort(*p.Manifest, sap.Name)
			if port == 0 {
				log.Printf("warning: no --port option for socket-activated port %q, assuming port %d as specified in the manifest", sap.Name, sap.Port)
				port = sap.Port
			}
			sockopts = append(sockopts, unit.NewUnitOption("Socket", proto, fmt.Sprintf("%v", port)))
		}

		file, err := os.OpenFile(SocketUnitPath(p.Root, appName), os.O_WRONLY|os.O_CREATE, 0644)
		if err != nil {
			return errwrap.Wrap(errors.New("failed to create socket file"), err)
		}
		defer file.Close()

		if _, err = io.Copy(file, unit.Serialize(sockopts)); err != nil {
			return errwrap.Wrap(errors.New("failed to write socket unit file"), err)
		}

		if err = os.Symlink(path.Join("..", SocketUnitName(appName)), SocketWantPath(p.Root, appName)); err != nil {
			return errwrap.Wrap(errors.New("failed to link socket want"), err)
		}

		opts = append(opts, unit.NewUnitOption("Unit", "Requires", SocketUnitName(appName)))
	}

	opts = append(opts, unit.NewUnitOption("Unit", "Requires", InstantiatedPrepareAppUnitName(appName)))
	opts = append(opts, unit.NewUnitOption("Unit", "After", InstantiatedPrepareAppUnitName(appName)))

	opts = append(opts, unit.NewUnitOption("Unit", "Requires", "sysusers.service"))
	opts = append(opts, unit.NewUnitOption("Unit", "After", "sysusers.service"))

	file, err := os.OpenFile(ServiceUnitPath(p.Root, appName), os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return errwrap.Wrap(errors.New("failed to create service unit file"), err)
	}
	defer file.Close()

	if _, err = io.Copy(file, unit.Serialize(opts)); err != nil {
		return errwrap.Wrap(errors.New("failed to write service unit file"), err)
	}

	if err = os.Symlink(path.Join("..", ServiceUnitName(appName)), ServiceWantPath(p.Root, appName)); err != nil {
		return errwrap.Wrap(errors.New("failed to link service want"), err)
	}

	if err = writeAppReaper(p, appName.String(), common.RelAppRootfsPath(appName), binPath); err != nil {
		return errwrap.Wrap(fmt.Errorf("failed to write app %q reaper service", appName), err)
	}

	return nil
}