fix(cmd): only allow the router to scale past 1

Author: Gabriel Monroy

README.md

@@ -81,6 +81,7 @@ Done.
 
 Note that the default install command activates 1 of each component.
 You can scale components with `deisctl scale router=3`, for example.
+The router is the only component that _currently_ scales beyond 1 unit.
 
 You can also use the `deisctl uninstall` command to destroy platform units:
 

cmd/cmd.go

@@ -47,8 +47,11 @@ func Scale(b backend.Backend, targets []string) error {
 		if err != nil {
 			return err
 		}
-		err = b.Scale(component, num)
-		if err != nil {
+		// the router is the only component that can scale past 1 at the moment
+		if num > 1 && !strings.Contains(component, "router") {
+			return fmt.Errorf("cannot scale %s past 1", component)
+		}
+		if err := b.Scale(component, num); err != nil {
 			return err
 		}
 	}