gsutil config -e

gsutil config -e
-e          Prompt for service account credentials. This option requires that ``-a`` is not set.

gsutil config -e
This command will create a boto config file at /Users/YOUR_USER/.boto
containing your credentials, based on your responses to the following
questions.
What is the full path to your private key file?

See also

• gsutil [ config | singurl | mb | iam | cp | ls | acl | defacl | ubla | du | cors | --help], $HOME/.boto, Cloud Shell