Ensuring service names are unique

nomad/structs/structs.go

@@ -1772,13 +1772,19 @@ func (t *Task) Validate() error {
 func validateServices(t *Task) error {
 	var mErr multierror.Error
 
-	// Ensure that services don't ask for non-existent ports.
+	// Ensure that services don't ask for non-existent ports and their names are
+	// unique.
 	servicePorts := make(map[string][]string)
+	knownServices := make(map[string]struct{})
 	for i, service := range t.Services {
 		if err := service.Validate(); err != nil {
 			outer := fmt.Errorf("service %d validation failed: %s", i, err)
 			mErr.Errors = append(mErr.Errors, outer)
 		}
+		if _, ok := knownServices[service.Name]; ok {
+			mErr.Errors = append(mErr.Errors, fmt.Errorf("service %q is duplicate", service.Name))
+		}
+		knownServices[service.Name] = struct{}{}
 
 		if service.PortLabel != "" {
 			servicePorts[service.PortLabel] = append(servicePorts[service.PortLabel], service.Name)

nomad/structs/structs_test.go

@@ -276,7 +276,7 @@ func TestTask_Validate(t *testing.T) {
 }
 
 func TestTask_Validate_Services(t *testing.T) {
-	s := &Service{
+	s1 := &Service{
 		Name:      "service-name",
 		PortLabel: "bar",
 		Checks: []*ServiceCheck{
@@ -287,6 +287,10 @@ func TestTask_Validate_Services(t *testing.T) {
 		},
 	}
 
+	s2 := &Service{
+		Name: "service-name",
+	}
+
 	task := &Task{
 		Name:   "web",
 		Driver: "docker",
@@ -296,7 +300,7 @@ func TestTask_Validate_Services(t *testing.T) {
 			MemoryMB: 100,
 			IOPS:     10,
 		},
-		Services: []*Service{s},
+		Services: []*Service{s1, s2},
 	}
 	err := task.Validate()
 	if err == nil {
@@ -305,6 +309,10 @@ func TestTask_Validate_Services(t *testing.T) {
 	if !strings.Contains(err.Error(), "referenced by services service-name does not exist") {
 		t.Fatalf("err: %s", err)
 	}
+
+	if !strings.Contains(err.Error(), "service \"service-name\" is duplicate") {
+		t.Fatalf("err: %v", err)
+	}
 }
 
 func TestTask_Validate_LogConfig(t *testing.T) {