Add support for update order

This parameter controls the order of operations when rolling out an
update task. Either the old task is stopped before starting the new one,
or the new task is started first, and the running tasks will briefly
overlap.

This commit adds Rollout to the API, and --update-order / --rollback-order
flags to the CLI.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

command/formatter/service.go

@@ -57,6 +57,7 @@ UpdateConfig:
  Monitoring Period: {{ .UpdateMonitor }}
 {{- end }}
  Max failure ratio: {{ .UpdateMaxFailureRatio }}
+ Update order:      {{ .UpdateOrder }}
 {{- end }}
 {{- if .HasRollbackConfig }}
 RollbackConfig:
@@ -69,6 +70,7 @@ RollbackConfig:
  Monitoring Period: {{ .RollbackMonitor }}
 {{- end }}
  Max failure ratio: {{ .RollbackMaxFailureRatio }}
+ Rollback order:    {{ .RollbackOrder }}
 {{- end }}
 ContainerSpec:
  Image:		{{ .ContainerImage }}
@@ -260,6 +262,10 @@ func (ctx *serviceInspectContext) UpdateOnFailure() string {
 	return ctx.Service.Spec.UpdateConfig.FailureAction
 }
 
+func (ctx *serviceInspectContext) UpdateOrder() string {
+	return ctx.Service.Spec.UpdateConfig.Order
+}
+
 func (ctx *serviceInspectContext) HasUpdateMonitor() bool {
 	return ctx.Service.Spec.UpdateConfig.Monitor.Nanoseconds() > 0
 }
@@ -304,6 +310,10 @@ func (ctx *serviceInspectContext) RollbackMaxFailureRatio() float32 {
 	return ctx.Service.Spec.RollbackConfig.MaxFailureRatio
 }
 
+func (ctx *serviceInspectContext) RollbackOrder() string {
+	return ctx.Service.Spec.RollbackConfig.Order
+}
+
 func (ctx *serviceInspectContext) ContainerImage() string {
 	return ctx.Service.Spec.TaskTemplate.ContainerSpec.Image
 }

command/service/opts.go

@@ -188,6 +188,7 @@ type updateOptions struct {
 	monitor         time.Duration
 	onFailure       string
 	maxFailureRatio floatValue
+	order           string
 }
 
 func (opts updateOptions) config() *swarm.UpdateConfig {
@@ -197,6 +198,7 @@ func (opts updateOptions) config() *swarm.UpdateConfig {
 		Monitor:         opts.monitor,
 		FailureAction:   opts.onFailure,
 		MaxFailureRatio: opts.maxFailureRatio.Value(),
+		Order:           opts.order,
 	}
 }
 
@@ -533,6 +535,8 @@ func addServiceFlags(flags *pflag.FlagSet, opts *serviceOptions) {
 	flags.StringVar(&opts.update.onFailure, flagUpdateFailureAction, "pause", `Action on update failure ("pause"|"continue"|"rollback")`)
 	flags.Var(&opts.update.maxFailureRatio, flagUpdateMaxFailureRatio, "Failure rate to tolerate during an update")
 	flags.SetAnnotation(flagUpdateMaxFailureRatio, "version", []string{"1.25"})
+	flags.StringVar(&opts.update.order, flagUpdateOrder, "stop-first", `Update order ("start-first"|"stop-first")`)
+	flags.SetAnnotation(flagUpdateOrder, "version", []string{"1.29"})
 
 	flags.Uint64Var(&opts.rollback.parallelism, flagRollbackParallelism, 1, "Maximum number of tasks rolled back simultaneously (0 to roll back all at once)")
 	flags.SetAnnotation(flagRollbackParallelism, "version", []string{"1.28"})
@@ -544,6 +548,8 @@ func addServiceFlags(flags *pflag.FlagSet, opts *serviceOptions) {
 	flags.SetAnnotation(flagRollbackFailureAction, "version", []string{"1.28"})
 	flags.Var(&opts.rollback.maxFailureRatio, flagRollbackMaxFailureRatio, "Failure rate to tolerate during a rollback")
 	flags.SetAnnotation(flagRollbackMaxFailureRatio, "version", []string{"1.28"})
+	flags.StringVar(&opts.rollback.order, flagRollbackOrder, "stop-first", `Rollback order ("start-first"|"stop-first")`)
+	flags.SetAnnotation(flagRollbackOrder, "version", []string{"1.29"})
 
 	flags.StringVar(&opts.endpoint.mode, flagEndpointMode, "vip", "Endpoint mode (vip or dnsrr)")
 
@@ -633,6 +639,7 @@ const (
 	flagRollbackFailureAction   = "rollback-failure-action"
 	flagRollbackMaxFailureRatio = "rollback-max-failure-ratio"
 	flagRollbackMonitor         = "rollback-monitor"
+	flagRollbackOrder           = "rollback-order"
 	flagRollbackParallelism     = "rollback-parallelism"
 	flagStopGracePeriod         = "stop-grace-period"
 	flagStopSignal              = "stop-signal"
@@ -641,6 +648,7 @@ const (
 	flagUpdateFailureAction     = "update-failure-action"
 	flagUpdateMaxFailureRatio   = "update-max-failure-ratio"
 	flagUpdateMonitor           = "update-monitor"
+	flagUpdateOrder             = "update-order"
 	flagUpdateParallelism       = "update-parallelism"
 	flagUser                    = "user"
 	flagWorkdir                 = "workdir"

command/service/update.go

@@ -320,7 +320,7 @@ func updateService(flags *pflag.FlagSet, spec *swarm.ServiceSpec) error {
 		return err
 	}
 
-	if anyChanged(flags, flagUpdateParallelism, flagUpdateDelay, flagUpdateMonitor, flagUpdateFailureAction, flagUpdateMaxFailureRatio) {
+	if anyChanged(flags, flagUpdateParallelism, flagUpdateDelay, flagUpdateMonitor, flagUpdateFailureAction, flagUpdateMaxFailureRatio, flagUpdateOrder) {
 		if spec.UpdateConfig == nil {
 			spec.UpdateConfig = &swarm.UpdateConfig{}
 		}
@@ -329,9 +329,10 @@ func updateService(flags *pflag.FlagSet, spec *swarm.ServiceSpec) error {
 		updateDuration(flagUpdateMonitor, &spec.UpdateConfig.Monitor)
 		updateString(flagUpdateFailureAction, &spec.UpdateConfig.FailureAction)
 		updateFloatValue(flagUpdateMaxFailureRatio, &spec.UpdateConfig.MaxFailureRatio)
+		updateString(flagUpdateOrder, &spec.UpdateConfig.Order)
 	}
 
-	if anyChanged(flags, flagRollbackParallelism, flagRollbackDelay, flagRollbackMonitor, flagRollbackFailureAction, flagRollbackMaxFailureRatio) {
+	if anyChanged(flags, flagRollbackParallelism, flagRollbackDelay, flagRollbackMonitor, flagRollbackFailureAction, flagRollbackMaxFailureRatio, flagRollbackOrder) {
 		if spec.RollbackConfig == nil {
 			spec.RollbackConfig = &swarm.UpdateConfig{}
 		}
@@ -340,6 +341,7 @@ func updateService(flags *pflag.FlagSet, spec *swarm.ServiceSpec) error {
 		updateDuration(flagRollbackMonitor, &spec.RollbackConfig.Monitor)
 		updateString(flagRollbackFailureAction, &spec.RollbackConfig.FailureAction)
 		updateFloatValue(flagRollbackMaxFailureRatio, &spec.RollbackConfig.MaxFailureRatio)
+		updateString(flagRollbackOrder, &spec.RollbackConfig.Order)
 	}
 
 	if flags.Changed(flagEndpointMode) {