How to Add Request IDs to Every Request in Express.js

Table Of Contents

• Quick Fix: UUID Request ID Middleware
• Express Built-in Solution: Using express-request-id

Quick Fix: UUID Request ID Middleware

const express = require('express');
const { v4: uuidv4 } = require('uuid');

// Create request ID middleware
const requestIdMiddleware = (req, res, next) => {
  // Check if client sent X-Request-Id header
  req.id = req.headers['x-request-id'] || uuidv4();
  
  // Add to response headers for client correlation
  res.setHeader('X-Request-Id', req.id);
  
  next();
};

const app = express();
app.use(requestIdMiddleware);

// Access request ID in any route
app.get('/api/users', (req, res) => {
  console.log(`[${req.id}] Processing user request`);
  res.json({ requestId: req.id, users: [] });
});

Express Built-in Solution: Using express-request-id

const express = require('express');
const requestId = require('express-request-id');

const app = express();

// Auto-generate request IDs
app.use(requestId({
  generator: () => require('crypto').randomUUID(),
  headerName: 'X-Request-Id'
}));

// Integrate with logging (Winston example)
const winston = require('winston');
const logger = winston.createLogger({
  format: winston.format.combine(
    winston.format.printf(({ level, message, ...meta }) => {
      const requestId = meta.requestId || 'no-request-id';
      return `[${requestId}] ${level}: ${message}`;
    })
  ),
  transports: [new winston.transports.Console()]
});

// Log with request ID
app.use((req, res, next) => {
  req.log = (message) => logger.info(message, { requestId: req.id });
  next();
});

app.get('/api/data', (req, res) => {
  req.log('Fetching data'); // Logs: [uuid-here] info: Fetching data
  res.json({ id: req.id });
});

Request IDs solve "correlating logs across microservices" issues and help debug "which request caused this error" problems. Express v4+ compatible, works with PM2 cluster mode. Alternative packages: cls-hooked for async context propagation, pino-http includes request IDs automatically.

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