Google API Authentication to access files/drives across the domain

[RohitJ]

Hello everyone, I am trying to build a service that fetches all files in the shared and user drives across a domain. Currently, I am using the service account key to generate the JWT (https://developers.google.com/identity/protocols/oauth2/service-account#authorizingrequests), and emailId is used to impersonate the user. The key generated is manually downloaded and used in the service via Kubernetes Secrets.

Is there any alternative approach? which reduces the manual action of downloading and uploading the file to secrets. 

The current approach also requires one service account per domain, it is possible to have one service account which I can use for any domain (not sure if it's really possible)? feel free to suggest any alternative approach which serves the same use case.