I am running on GKE one of the service that interact with Google API. Per this documentation Calendar API I should be able to obtain Application Default Credentials and able to make calls but getting insufficient permission issue. However other services Pub/Sub, Firestore seems able to obtain credentials by loading Project ID.

2019/11/02 06:20:07.489551 errors.go:54: a512ac94d0ecb0bd93c8cac73c88d9b1 : ERROR : googleapi: Error 403: Insufficient Permission: Request had insufficient authentication scopes., insufficientPermissions

For now I decided to gen token and it is working fine. I just do not want to manage that token and was wondering if I can get it working without it since I am in GKE env already.