Authentication using service credentials

[Techbrunch]

Hello,

I'm probably doing something stupid but I want to login using service credentials and I'm getting an error:

root@63736ec27f18:/gcp# service pentest gcp.json
pentest: unrecognized service

The wiki says:

Service Credentials:: If you want to supply service account credentials, than you would just enter service <arbitrary_credential_name> <path_to_JSON_file>

I have successfully added the credentials to gcloud using the following command:

gcloud auth activate-service-account --key-file=gcp.json
Activated service account credentials for: [REDACTED]