Comment 3 for bug 1856286

python-keystoneclient uses keystoneauth sessions and therefore supports any auth method that keystoneauth supports. keystoneauth has support for the application credential auth method:

https://docs.openstack.org/keystoneauth/latest/authentication-plugins.html#application-credentials

See the following for using keystoneauth in keystoneclient:

https://docs.openstack.org/keystoneauth/latest/using-sessions.html#sessions-for-users