'Check nova-instance-instance-xxx exists.'

def instance_filter_exists(self, instance, network_info):

    for vif in network_info:
        nic_id = vif['address'].replace(':', '')
        instance_filter_name = self._instance_filter_name(instance, nic_id)
        try:
            self._conn.nwfilterLookupByName(instance_filter_name)
        except libvirt.libvirtError:
            name = instance.name
            LOG.debug('The    nwfilter(%(instance_filter_name)s)    for%(name)s    is    not    found.', {'instance_filter_name': instance_filter_name, 'name': name}, instance=instance)
            return False
    return True
