Add `--tty` to `docker service create/update`

This fix tries to add `--tty` to `docker service create/update`. As was
specified in 25644, `TTY` flag has been added to SwarmKit and is
already vendored.

This fix add `--tty` to `docker service create/update`.

Related document has been updated.

Additional integration tests has been added.

This fix fixes 25644.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

command/service/opts.go

@@ -294,6 +294,7 @@ type serviceOptions struct {
 	workdir         string
 	user            string
 	groups          []string
+	tty             bool
 	mounts          opts.MountOpt
 
 	resources resourceOptions
@@ -365,6 +366,7 @@ func (opts *serviceOptions) ToService() (swarm.ServiceSpec, error) {
 				Dir:             opts.workdir,
 				User:            opts.user,
 				Groups:          opts.groups,
+				TTY:             opts.tty,
 				Mounts:          opts.mounts.Value(),
 				StopGracePeriod: opts.stopGrace.Value(),
 			},
@@ -450,6 +452,8 @@ func addServiceFlags(cmd *cobra.Command, opts *serviceOptions) {
 	flags.Var(&opts.healthcheck.timeout, flagHealthTimeout, "Maximum time to allow one check to run")
 	flags.IntVar(&opts.healthcheck.retries, flagHealthRetries, 0, "Consecutive failures needed to report unhealthy")
 	flags.BoolVar(&opts.healthcheck.noHealthcheck, flagNoHealthcheck, false, "Disable any container-specified HEALTHCHECK")
+
+	flags.BoolVarP(&opts.tty, flagTTY, "t", false, "Allocate a pseudo-TTY")
 }
 
 const (
@@ -490,6 +494,7 @@ const (
 	flagRestartMaxAttempts    = "restart-max-attempts"
 	flagRestartWindow         = "restart-window"
 	flagStopGracePeriod       = "stop-grace-period"
+	flagTTY                   = "tty"
 	flagUpdateDelay           = "update-delay"
 	flagUpdateFailureAction   = "update-failure-action"
 	flagUpdateMaxFailureRatio = "update-max-failure-ratio"

command/service/update.go

@@ -274,6 +274,14 @@ func updateService(flags *pflag.FlagSet, spec *swarm.ServiceSpec) error {
 		return err
 	}
 
+	if flags.Changed(flagTTY) {
+		tty, err := flags.GetBool(flagTTY)
+		if err != nil {
+			return err
+		}
+		cspec.TTY = tty
+	}
+
 	return nil
 }