@classmethod
def from_ip(cls, ip):
    """Retrieve webacc id associated to a webacc ip"""
    result = cls.list({'items_per_page': 500})
    webaccs = {}
    for webacc in result:
        for server in webacc['servers']:
            webaccs[server['ip']] = webacc['id']
    return webaccs.get(ip)
