func runJoin(dockerCli command.Cli, flags *pflag.FlagSet, opts joinOptions) error {
	client := dockerCli.Client()
	ctx := context.Background()

	req := swarm.JoinRequest{
		JoinToken:     opts.token,
		ListenAddr:    opts.listenAddr.String(),
		AdvertiseAddr: opts.advertiseAddr,
		RemoteAddrs:   []string{opts.remote},
	}
	if flags.Changed(flagAvailability) {
		availability := swarm.NodeAvailability(strings.ToLower(opts.availability))
		switch availability {
		case swarm.NodeAvailabilityActive, swarm.NodeAvailabilityPause, swarm.NodeAvailabilityDrain:
			req.Availability = availability
		default:
			return fmt.Errorf("invalid availability %q, only active, pause and drain are supported", opts.availability)
		}
	}

	err := client.SwarmJoin(ctx, req)
	if err != nil {
		return err
	}

	info, err := client.Info(ctx)
	if err != nil {
		return err
	}

	if info.Swarm.ControlAvailable {
		fmt.Fprintln(dockerCli.Out(), "This node joined a swarm as a manager.")
	} else {
		fmt.Fprintln(dockerCli.Out(), "This node joined a swarm as a worker.")
	}
	return nil
}

// Join joins a daemon to an existing cluster.
func (d *SwarmDaemon) Join(req swarm.JoinRequest) error {
	if req.ListenAddr == "" {
		req.ListenAddr = d.listenAddr
	}
	status, out, err := d.SockRequest("POST", "/swarm/join", req)
	if status != http.StatusOK {
		return fmt.Errorf("joining swarm: invalid statuscode %v, %q", status, out)
	}
	if err != nil {
		return fmt.Errorf("joining swarm: %v", err)
	}
	info, err := d.info()
	if err != nil {
		return err
	}
	d.Info = info
	return nil
}