def _pick_random_nic(self):
        ctxt = self.context
        nets = [net["id"]
                for net in ctxt.get("tenant", {}).get("networks", [])]
        if nets:
            # NOTE(amaretskiy): Balance servers among networks.
            net_idx = self.context["iteration"] % len(nets)
            return [{"net-id": nets[net_idx]}]
Choose one network from existing ones.
dataset/ETHPy150Open openstack/rally/rally/plugins/openstack/scenarios/nova/utils.py/NovaScenario._pick_random_nic