Require RFC-1123 and RFC-2782 valid service names

nomad/structs/structs.go

@@ -1510,10 +1510,13 @@ func (s *Service) InitFields(job string, taskGroup string, task string) {
 func (s *Service) Validate() error {
 	var mErr multierror.Error
 
-	// Ensure the name does not have a period in it.
-	// RFC-2782: https://tools.ietf.org/html/rfc2782
-	if strings.Contains(s.Name, ".") {
-		mErr.Errors = append(mErr.Errors, fmt.Errorf("service name can't contain periods: %q", s.Name))
+	// Ensure the service name is valid per RFC-952 §1
+	// (https://tools.ietf.org/html/rfc952), RFC-1123 §2.1
+	// (https://tools.ietf.org/html/rfc1123), and RFC-2782
+	// (https://tools.ietf.org/html/rfc2782).
+	re := regexp.MustCompile(`^(?i:[a-z0-9]|[a-z0-9][a-z0-9\-]{0,61}[a-z0-9])$`)
+	if !re.MatchString(s.Name) {
+		mErr.Errors = append(mErr.Errors, fmt.Errorf("service name must be valid per RFC 1123 and can contain only alphanumeric characters or dashes and must be less than 63 characters long: %q", s.Name))
 	}
 
 	for _, c := range s.Checks {

nomad/structs/structs_test.go

@@ -519,15 +519,31 @@ func TestInvalidServiceCheck(t *testing.T) {
 		},
 	}
 	if err := s.Validate(); err == nil {
-		t.Fatalf("Service should be invalid")
+		t.Fatalf("Service should be invalid (invalid type)")
 	}
 
 	s = Service{
 		Name:      "service.name",
 		PortLabel: "bar",
 	}
 	if err := s.Validate(); err == nil {
-		t.Fatalf("Service should be invalid: %v", err)
+		t.Fatalf("Service should be invalid (contains a dot): %v", err)
+	}
+
+	s = Service{
+		Name:      "-my-service",
+		PortLabel: "bar",
+	}
+	if err := s.Validate(); err == nil {
+		t.Fatalf("Service should be invalid (begins with a hyphen): %v", err)
+	}
+
+	s = Service{
+		Name:      "abcdef0123456789-abcdef0123456789-abcdef0123456789-abcdef0123456",
+		PortLabel: "bar",
+	}
+	if err := s.Validate(); err == nil {
+		t.Fatalf("Service should be invalid (too long): %v", err)
 	}
 }
 

website/source/docs/jobspec/servicediscovery.html.md

@@ -76,13 +76,17 @@ group "database" {
 ```
 
 * `name`: Nomad automatically determines the name of a Task. By default the
-  name of a service is $(job-name)-$(task-group)-$(task-name). Users can
+  name of a service is `$(job-name)-$(task-group)-$(task-name)`. Users can
   explicitly name the service by specifying this option. If multiple services
-  are defined for a Task then only one task can have the default name, all the
-  services have to be explicitly named. Users can add the following to the
-  service names: ```${JOB}```, ```${TASKGROUP}```, ```${TASK}```, ```${BASE}```. 
-  Nomad will replace them with the appropriate value of the Job, Task Group and 
-  Task names while registering the Job. ```${BASE}``` expands to ${JOB}-${TASKGROUP}-${TASK}
+  are defined for a Task then only one task can have the default name, all
+  the services have to be explicitly named.  Users can add the following to
+  the service names: `${JOB}`, `${TASKGROUP}`, `${TASK}`, `${BASE}`.  Nomad
+  will replace them with the appropriate value of the Job, Task Group, and
+  Task names while registering the Job. `${BASE}` expands to
+  `${JOB}-${TASKGROUP}-${TASK}`.  Names must be adhere to
+  [RFC-1123 §2.1](https://tools.ietf.org/html/rfc1123#section-2) and are
+  limited to alphanumeric and hyphen characters (i.e. `[a-z0-9\-]`), and be
+  less than 64 characters in length.
 
 * `tags`: A list of tags associated with this Service.