tools/run_tests/xds/bootstrap.json

{
  "node": {
    "id": "doesnt matter",
    "locality": {
      "zone": "us-central1-a",
      "region": "region",
      "sub_zone": "sub_zone"
    },
    "metadata": {
      "TRAFFICDIRECTOR_GRPC_HOSTNAME": "",
      "TRAFFICDIRECTOR_NETWORK_NAME": ""
    }
  },
  "xds_servers": [{
    "server_uri": "trafficdirector.googleapis.com:443",
    "channel_creds": [
      {
        "type": "google_default",
        "config": {}
      }
    ]
  }]
}