img_conf = {
    'mirror_url': 'https://cloud-images.ubuntu.com/daily',
    'release': 'bionic',
    'keyring': '/usr/share/keyrings/ubuntu-cloudimage-keyring.gpg',
    'mirror_dir': '/srv/citest/nocloud-kvm'
}

(url, path) = s_util.path_from_mirror_url(
    img_conf['mirror_url'], None
)

filter = filters.get_filters([   
    'content_id=com.ubuntu.cloud:daily:aws',                        
    'release=%s' % img_conf['release'],
    'crsn=us-west-2',
    'root_store=ssd',
    'virt=hvm',
])

mirror_config = {
    'filters': filter,
    'keep_items': False,
    'max_items': 1,
    'checksumming_reader': True,
    'item_download': True,
}
        
smirror = mirrors.UrlMirrorReader(url, policy=policy)
tstore = objectstores.FileStore(img_conf['mirror_dir'])
tmirror = mirrors.ObjectFilterMirror(config=mirror_config,
                                     objectstore=tstore)
tmirror.sync(smirror, path)