Reading secret config file on Heroku without using env vars

Was answered by the lovely folks over at GoogleCloudPlatform: https://github.com/GoogleCloudPlatform/gcloud-node/issues/761

It's not mentioned in the code sample in the documentation, but you can just add a credentials object and pass that to your config. The credentials object can read env vars.

More information here: https://googlecloudplatform.github.io/gcloud-node/#/authorization.
Updated link: https://googleapis.dev/nodejs/pubsub/latest/global.html#ClientConfig