code: def authenticate_glance_admin(self, keystone, force_v1_client=False):
          
          self.log.debug('Authenticating glance admin...')
          ep = keystone.service_catalog.url_for(service_type='image',
                                                interface='adminURL')
          if not force_v1_client and keystone.session:
              return glance_clientv2.Client("2", session=keystone.session)
          else:
              return glance_client.Client(ep, token=keystone.auth_token)
docs: Authenticates admin user with glance.