What is the equivalent rest api calls for these?
gcloud auth activate-service-account --key-file=myvaultkey.json
export GOOGLE_OAUTH_ACCESS_TOKEN=$(gcloud auth print-access-token)
See Use OAuth2 for Server to Server Applications
You can get gcloud
to show underlying REST API calls by appending --log-http
to any command.
In this case, some of the work involves updating gcloud
's local configuration to use the Service Account but you can ignore that part and focus on creating a JWT and using that to get an access token that you can then use to invoke the API(s).
I encourage you to use one of Google's SDKs rather than do this using the underlying APIs. The documentation page referenced above explains both approaches and you'll see that using a SDK is not only trivial but it provides strong assurance that you're implementing the flow correctly (securely).