Populating service ids only if allocations can be placed for system jobs

nomad/structs/structs.go

@@ -1508,7 +1508,7 @@ func (a *Allocation) PopulateServiceIDs() {
 	for _, task := range tg.Tasks {
 		for _, service := range task.Services {
 			// We add a prefix to the Service ID so that we can know that this service
-			// is managed by Nomad Consul since Consul can also have service which are not
+			// is managed by Nomad since Consul can also have service which are not
 			// managed by Nomad
 			a.Services[service.Name] = fmt.Sprintf("%s-%s", NomadConsulPrefix, GenerateUUID())
 		}

scheduler/system_sched.go

@@ -246,12 +246,12 @@ func (s *SystemScheduler) computePlacements(place []allocTuple) error {
 			Metrics:   s.ctx.Metrics(),
 		}
 
-		// Generate the service ids for the tasks that this allocation is going
-		// to run
-		alloc.PopulateServiceIDs()
-
 		// Set fields based on if we found an allocation option
 		if option != nil {
+			// Generate the service ids for the tasks that this allocation is going
+			// to run
+			alloc.PopulateServiceIDs()
+
 			alloc.NodeID = option.Node.ID
 			alloc.TaskResources = option.TaskResources
 			alloc.DesiredStatus = structs.AllocDesiredStatusRun