How can I authorize a Google Service Account without the default credentials file?

Question

I have a Google Service Account that my app uses to retrieve data from Google Analytics.

When I created the account I downloaded a client_secrets file with

Answer 1

I found the answer in the source code of the google-auth-library-ruby gem.

It turns out that there is another option: take the values from the client_secrets file and put them in environment variables named GOOGLE_ACCOUNT_TYPE, GOOGLE_CLIENT_ID, GOOGLE_CLIENT_EMAIL and GOOGLE_PRIVATE_KEY respectively.

If these keys are populated, the credentials will load from there. Not a whisper of this in the docs, though.