title: Allowing an App Engine app to access another App Engine app's datastore
body: <p>I have a situation where an existing GAE App (let's call it app A) is running, but for non-technical reasons can't be modified.  As users migrates to a new client version, we need to migrate their data from app A to a new GAE app (which I'll call app B).</p>
  
  <p>Is there a way that I can grant app B access to app A's live datastore without modifying app A?  My not modifying I mean not having to deploy new code.  Changing setting or permissions in the Cloud Console is fine.</p>
  
  <p>In case it matters, both apps that I'm referring to are written in Go.</p>