firebase-admin already lookup gcloud application default credentials out of the box:

It would awesome if it could also look up firebase-tools credentials in a similar fashion, so that:

const admin = require('firebase-admin');

admin.initializeApp({
  credential: admin.credential.applicationDefault()
});

could just work for `firebase-tools users without requiring the user to install gcloud or download service account key to their development environment.

Note you can workaround this today by doing:

const admin = require('firebase-admin');

admin.initializeApp({
  credential: admin.credential.refreshToken({type: 'authorized_user', refresh_token: (new (require('configstore'))('firebase-tools')).get('tokens.refresh_token'), client_id: require('firebase-tools/lib/api').clientId, client_secret: require('firebase-tools/lib/api').clientSecret})
});

But it seems quite fragile if firebase-tools ever decide to change the location of the refresh token / client id / secret.