title: Getting Google IdToken for service account?
body: <p>I have a backend that is serving android clients, authenticating them with IdToken sent from the android app.
  Now, I need to authenticate a service running on aws that is using my apis. So I figured a service account would do the trick, using the private pem file to create a IdToken and send it along just as the android clients do. But I find no way of obtaining an IdToken with these credentials. Is this possible (preferrably in nodejs).
  Or am I on the wrong path here?</p>