~~Please leave this on hold until we move the credential dance into oauth2client and update apitools, I will update this issue tomorrow.~~ Things to be done (added by @dhermes): - [x] Use `oauth2client.client.GoogleCredentials.get_application_default()`. ~~This still is "open" due to google/oauth2client#93~~ - [x] Cover GAE service accounts (done via implicit in `get_application_default`) - [x] Cover GCE service accounts (done via implicit in `get_application_default`) - [x] Cover JSON service account credentials (done via implicit in `get_application_default`) - [ ] Cover 3LO for people just getting started (#539) - [x] Cover p12 service account credentials (moved in #412 to `gcloud.credentials.get_for_service_account_p12`)