How to use certbot-dns-google - 3 common examples

def _get_google_client(self):
        return _GoogleClient(self.conf('credentials'))

def _setup_credentials(self):
        if self.conf('credentials') is None:
            try:
                # use project_id query to check for availability of google metadata server
                # we won't use the result but know we're not on GCP when an exception is thrown
                _GoogleClient.get_project_id()
            except (ValueError, httplib2.ServerNotFoundError):
                raise errors.PluginError('Unable to get Google Cloud Metadata and no credentials'
                                         ' specified. Automatic credential lookup is only '
                                         'available on Google Cloud Platform. Please configure'
                                         ' credentials using --dns-google-credentials ')
        else:
            self._configure_file('credentials',
                                 'path to Google Cloud DNS service account JSON file')

            dns_common.validate_file_permissions(self.conf('credentials'))

def __init__(self, *args, **kwargs):
        super(Authenticator, self).__init__(*args, **kwargs)
        self.credentials = None