@metadata_processor
def add_users_to_libvirt_group(metadata):
    if 'users' in metadata:
        for user in metadata['users']:
            if 'groups' not in metadata['users'][user]:
                metadata['users'][user]['groups'] = []

            if 'libvirt' not in metadata['users'][user]['groups']:
                metadata['users'][user]['groups'].append('libvirt')

    return metadata, RUN_ME_AGAIN