Fix up validation and allow existing unset timeouts to continue to be unset

nomad/structs/structs.go

@@ -1482,6 +1482,7 @@ func (tg *TaskGroup) GoString() string {
 }
 
 const (
+	// TODO add Consul TTL check
 	ServiceCheckHTTP   = "http"
 	ServiceCheckTCP    = "tcp"
 	ServiceCheckScript = "script"
@@ -1522,26 +1523,32 @@ func (sc *ServiceCheck) Copy() *ServiceCheck {
 func (sc *ServiceCheck) validate() error {
 	switch strings.ToLower(sc.Type) {
 	case ServiceCheckTCP:
+		if sc.Timeout > 0 && sc.Timeout <= minCheckTimeout {
+			return fmt.Errorf("timeout %v is lower than required minimum timeout %v", sc.Timeout, minCheckInterval)
+		}
 	case ServiceCheckHTTP:
 		if sc.Path == "" {
 			return fmt.Errorf("http type must have a valid http path")
 		}
+
+		if sc.Timeout > 0 && sc.Timeout <= minCheckTimeout {
+			return fmt.Errorf("timeout %v is lower than required minimum timeout %v", sc.Timeout, minCheckInterval)
+		}
 	case ServiceCheckScript:
 		if sc.Command == "" {
 			return fmt.Errorf("script type must have a valid script path")
 		}
+
+		// TODO: enforce timeout on the Client side and reenable
+		// validation.
 	default:
 		return fmt.Errorf(`invalid type (%+q), must be one of "http", "tcp", or "script" type`, sc.Type)
 	}
 
-	if sc.Interval <= minCheckInterval {
+	if sc.Interval > 0 && sc.Interval <= minCheckInterval {
 		return fmt.Errorf("interval (%v) can not be lower than %v", sc.Interval, minCheckInterval)
 	}
 
-	if sc.Timeout <= minCheckTimeout {
-		return fmt.Errorf("timeout %v is lower than required minimum timeout %v", sc.Timeout, minCheckInterval)
-	}
-
 	return nil
 }