Add support for maximum replicas per node

Signed-off-by: Olli Janatuinen <olli.janatuinen@gmail.com>

Author: olljanat

cli/command/service/formatter.go

@@ -49,6 +49,9 @@ Placement:
 {{- if .TaskPlacementPreferences }}
  Preferences:   {{ .TaskPlacementPreferences }}
 {{- end }}
+{{- if .MaxReplicas }}
+ Max Replicas Per Node:   {{ .MaxReplicas }}
+{{- end }}
 {{- if .HasUpdateConfig }}
 UpdateConfig:
  Parallelism:	{{ .UpdateParallelism }}
@@ -284,6 +287,13 @@ func (ctx *serviceInspectContext) TaskPlacementPreferences() []string {
 	return strings
 }
 
+func (ctx *serviceInspectContext) MaxReplicas() uint64 {
+	if ctx.Service.Spec.TaskTemplate.Placement != nil {
+		return ctx.Service.Spec.TaskTemplate.Placement.MaxReplicas
+	}
+	return 0
+}
+
 func (ctx *serviceInspectContext) HasUpdateConfig() bool {
 	return ctx.Service.Spec.UpdateConfig != nil
 }

cli/command/service/list.go

@@ -120,9 +120,16 @@ func GetServicesStatus(services []swarm.Service, nodes []swarm.Node, tasks []swa
 	for _, service := range services {
 		info[service.ID] = ListInfo{}
 		if service.Spec.Mode.Replicated != nil && service.Spec.Mode.Replicated.Replicas != nil {
-			info[service.ID] = ListInfo{
-				Mode:     "replicated",
-				Replicas: fmt.Sprintf("%d/%d", running[service.ID], *service.Spec.Mode.Replicated.Replicas),
+			if service.Spec.TaskTemplate.Placement != nil && service.Spec.TaskTemplate.Placement.MaxReplicas > 0 {
+				info[service.ID] = ListInfo{
+					Mode:     "replicated",
+					Replicas: fmt.Sprintf("%d/%d (max %d per node)", running[service.ID], *service.Spec.Mode.Replicated.Replicas, service.Spec.TaskTemplate.Placement.MaxReplicas),
+				}
+			} else {
+				info[service.ID] = ListInfo{
+					Mode:     "replicated",
+					Replicas: fmt.Sprintf("%d/%d", running[service.ID], *service.Spec.Mode.Replicated.Replicas),
+				}
 			}
 		} else if service.Spec.Mode.Global != nil {
 			info[service.ID] = ListInfo{

cli/command/service/opts.go

@@ -499,6 +499,7 @@ type serviceOptions struct {
 	restartPolicy  restartPolicyOptions
 	constraints    opts.ListOpts
 	placementPrefs placementPrefOpts
+	maxReplicas    uint64
 	update         updateOptions
 	rollback       updateOptions
 	networks       opts.NetworkOpt
@@ -540,6 +541,10 @@ func (options *serviceOptions) ToServiceMode() (swarm.ServiceMode, error) {
 			return serviceMode, errors.Errorf("replicas can only be used with replicated mode")
 		}
 
+		if options.maxReplicas > 0 {
+			return serviceMode, errors.Errorf("replicas-max-per-node can only be used with replicated mode")
+		}
+
 		serviceMode.Global = &swarm.GlobalService{}
 	case "replicated":
 		serviceMode.Replicated = &swarm.ReplicatedService{
@@ -644,6 +649,7 @@ func (options *serviceOptions) ToService(ctx context.Context, apiClient client.N
 			Placement: &swarm.Placement{
 				Constraints: options.constraints.GetAll(),
 				Preferences: options.placementPrefs.prefs,
+				MaxReplicas: options.maxReplicas,
 			},
 			LogDriver: options.logDriver.toLogDriver(),
 		},
@@ -746,6 +752,7 @@ func addServiceFlags(flags *pflag.FlagSet, opts *serviceOptions, defaultFlagValu
 
 	flags.Var(&opts.stopGrace, flagStopGracePeriod, flagDesc(flagStopGracePeriod, "Time to wait before force killing a container (ns|us|ms|s|m|h)"))
 	flags.Var(&opts.replicas, flagReplicas, "Number of tasks")
+	flags.Uint64Var(&opts.maxReplicas, flagMaxReplicas, defaultFlagValues.getUint64(flagMaxReplicas), "Maximum number of tasks per node (default 0 = unlimited)")
 
 	flags.StringVar(&opts.restartPolicy.condition, flagRestartCondition, "", flagDesc(flagRestartCondition, `Restart when condition is met ("none"|"on-failure"|"any")`))
 	flags.Var(&opts.restartPolicy.delay, flagRestartDelay, flagDesc(flagRestartDelay, "Delay between restart attempts (ns|us|ms|s|m|h)"))
@@ -852,6 +859,7 @@ const (
 	flagLabelAdd                = "label-add"
 	flagLimitCPU                = "limit-cpu"
 	flagLimitMemory             = "limit-memory"
+	flagMaxReplicas             = "replicas-max-per-node"
 	flagMode                    = "mode"
 	flagMount                   = "mount"
 	flagMountRemove             = "mount-rm"

cli/command/service/update.go

@@ -387,6 +387,10 @@ func updateService(ctx context.Context, apiClient client.NetworkAPIClient, flags
 		return err
 	}
 
+	if anyChanged(flags, flagMaxReplicas) {
+		updateUint64(flagMaxReplicas, &task.Placement.MaxReplicas)
+	}
+
 	if anyChanged(flags, flagUpdateParallelism, flagUpdateDelay, flagUpdateMonitor, flagUpdateFailureAction, flagUpdateMaxFailureRatio, flagUpdateOrder) {
 		if spec.UpdateConfig == nil {
 			spec.UpdateConfig = updateConfigFromDefaults(defaults.Service.Update)

cli/compose/convert/service.go

@@ -158,6 +158,7 @@ func Service(
 			Placement: &swarm.Placement{
 				Constraints: service.Deploy.Placement.Constraints,
 				Preferences: getPlacementPreference(service.Deploy.Placement.Preferences),
+				MaxReplicas: service.Deploy.Placement.MaxReplicas,
 			},
 		},
 		EndpointSpec:   endpoint,