current_iteration = self.context["iteration"]
availability_zones = self._list_availability_zones()

az_to_use = availability_zones[current_iteration % len(availability_zones)]
networks_to_use = [{"net-id": net["id"]} for net in ctxt.get("tenant", {}).get("networks", []) 
                   if net["availability_zone"] == az_to_use.name]
server = self._boot_server(image, flavor, availability_zone=az.name, nics=networks_to_use, **kwargs)
    self.sleep_between(min_sleep, max_sleep)
self._delete_server(server, force=force_delete)