trace-1139.js

const tracer = require('@google-cloud/trace-agent').start();

const express = require('express');

const app = express();

// Middleware that just adds a label to each trace.
app.use((req, res, next) => {
  tracer.getCurrentRootSpan().addLabel('key', 'value');
  next();
});

app.get('/', async (req, res) => {
  res.send('hello world!');
});

app.listen(process.env.PORT || 8080);