Set Up a Basic Webhook Receiver with Node.js Express

const express = require('express');
const bodyParser = require('body-parser'); // To parse JSON bodies
const crypto = require('crypto'); // For signature verification

const app = express();
const port = 3000;
const WEBHOOK_SECRET = 'your_super_secret_webhook_key'; // Replace with a strong, secret key

// Middleware to parse JSON bodies
app.use(bodyParser.json());

// Basic authentication middleware (optional, but highly recommended for webhooks)
// This example uses a shared secret in a custom header or body, a real implementation
// might use a more robust signature verification (e.g., HMAC-SHA256)
function verifyWebhookSignature(req, res, next) {
  const signature = req.headers['x-webhook-signature']; // Example header
  // For services that send HMAC signature:
  // const hmac = crypto.createHmac('sha256', WEBHOOK_SECRET);
  // hmac.update(JSON.stringify(req.body));
  // const digest = 'sha256=' + hmac.digest('hex');

  // Simple shared secret check (less secure, use signature verification if possible)
  if (signature === WEBHOOK_SECRET) { // Or compare `digest` if using HMAC
    next(); // Signature valid, proceed to handler
  } else {
    console.warn('Webhook signature mismatch or missing.');
    res.status(403).send('Forbidden: Invalid webhook signature');
  }
}

// Webhook endpoint
app.post('/webhook/data-update', verifyWebhookSignature, (req, res) => {
  console.log('Received webhook notification!');
  const eventData = req.body; // The data sent by the webhook
  console.log('Event data:', eventData);

  // Process the event data here
  // For example: update a database, send an email, trigger another process.
  // Make sure to respond quickly to avoid webhook provider timeouts.
  // Asynchronous tasks can be handled after responding.
  processWebhookAsync(eventData); // Example async processing

  res.status(200).send('Webhook received and acknowledged.');
});

async function processWebhookAsync(data) {
  console.log('Asynchronously processing webhook data...');
  // Simulate a long-running task
  await new Promise(resolve => setTimeout(resolve, 2000));
  console.log('Webhook data processed:', data);
  // Further actions like updating database, sending notifications, etc.
}

app.listen(port, () => {
  console.log(`Webhook receiver listening at http://localhost:${port}`);
  console.log(`Configure your external service to send POST requests to http://your-server-ip:${port}/webhook/data-update`);
});