def authentication_data(manila_plugin):
    """Return the authentication dictionary for use in the manila.conf template

        The authentication data format is:
        {
            'username': <value>
            'password': <value>
            'project_domain_name': <value>
            'project_name': <value>
            'user_domain_name': <value>
            'auth_uri': <value>
            'auth_url': <value>
            'auth_type': <value>  # 'password', typically
        }

    :param manila_plugin: the charms.reactive relation instance.
    :returns: dict described above
    """
    return manila_plugin.relation.authentication_data