defaults = {
    'apt': {
        'packages': {
            'postfix': {},
        },
    },
}

@metadata_reactor
def letsencrypt(metadata):
    if not node.has_bundle('letsencrypt'):
        raise DoNotRunAgain

    result = {
        'reload_after': {
            'postfix',
        },
    }

    myhostname = metadata.get('postfix/myhostname', None)

    if myhostname and myhostname != metadata.get('hostname'):
        result['domains'] = {
            myhostname: {},
        }

    return {
        'letsencrypt': result,
    }