server.js

const ah = require('async_hooks');
const express = require('express');
const { createLogger } = require('winston');
const TransportStream = require('winston-transport');

// Activate async hooks.
let requestIdHighWater = 0;
const requestIdTable = {};
ah.createHook({
  init: (child, resource, parent) => {
    requestIdTable[child] = requestIdTable[parent];
  }
}).enable();

// OUR CODE

class MyTransport extends TransportStream {
  log(info, next) {
    // From the transport, the request ID is not reliable.
    const actualRequestId = requestIdTable[ah.executionAsyncId()];
    console.log(`Expected: ${info.expectedRequestId}, Actual: ${actualRequestId}`);
    setImmediate(next);
  }
}

// OUR USER'S CODE

const logger = createLogger({
  defaultMeta: {
    expectedRequestId: () => {
      // Store a request ID.
      const requestId = requestIdHighWater++;
      requestIdTable[ah.executionAsyncId()] = requestId;
      return requestId;
    }
  },
  transports: [new MyTransport()]
});

const app = express();

app.get('/', async (req, res) => {
  logger.info('hello');
  res.sendStatus(200);
});

app.listen(3000);