Google Cloud Functions + Stripe Webhook signing

index.js

/**
 * Responds to any HTTP request that can provide a "message" field in the body.
 *
 * @param {!Object} req Cloud Function request context.
 * @param {!Object} res Cloud Function response context.
 */
exports.webhook = (req, res) => {
// Required environment variables:
//  WEBHOOK_SIGNING_KEY -- the whsec_xxx value displayed when you enable webhook signing for your endpoint
//  STRIPE_SECRET_KEY -- your Stripe secret key

  const endpointSecret = process.env.WEBHOOK_SIGNING_KEY;
  
  try {
    const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);

    // GCF lowercases all header names, just like AWS Lambda
    const event = stripe.webhooks.constructEvent(req.rawBody, req.headers['stripe-signature'], endpointSecret);
    res.send(JSON.stringify(event));
  }
  catch (err) {
      res.status(500).send('Bad Failure: ' + err);
  }
};