Stripe Event validation in a Gatsby Serverless Function  λ 💰

If you are new to serverless, you might have thought nothing of yesterday's "Using Http Request Body" example.

export default function handler(req, res) {
  const { city, year } = req.body;
  res.send(`You time-travelled to ${city}, in year ${year}`);

But having the body served to you automagically as json, when it makes sense, is something I really like about Gatsby Functions. In most other serverless implementations, you have to parse it yourself.

However, when it comes to verifying the signature of a webhook using a third-party SDK, not so much! Most signature checks require access to the raw body.

And for the longest time, we could not access the raw body in a Gatsby Function, but with the release of Gatbsy v4.14, we can 🎉

To control the body-parser middleware export an object named config.

const stripe = require("stripe")(process.env.STRIPE_SECRET_KEY);
const endpointSecret = process.env.STRIPE_ENDPOINT_SECRET;

// Export a config object
// to configure the bodyParser
export const config = {
  bodyParser: {
    raw: {
      type: `*/*`,

export default function handler(req, res) {
  try {
    const sig = req.headers["stripe-signature"];
    const event = stripe.webhooks.constructEvent(req.body, sig, endpointSecret);

    // Handle the verified event,
    // event data can be trusted
    switch (event.type) {
      case "checkout.session.completed":
        console.log("CheckoutSession completed, fulfill the order!");
        // Handle the event
      // ... handle other event types
        console.log(`Unhandled event type ${event.type}`);

  } catch (err) {

Unfortunately, I cannot seem to make this work locally, but I have verified that it works on Gatsby Cloud. I will, of course, follow up with Gatsby to figure out what's up. Is it a feature? Or a bug? I know my opinion on the matter 😬

Update: Raw body works in develop from v4.16

All the best,
Queen Raae

Stuck on a reef in the sharky waters around the Gatsby islands?

Book a 1-on-1 Gatsby Call with Queen Raae. Friendly advice you can put into action immediately, guaranteed!

Serious about Gatsby? Sign up for emails sent every weekday to help you get the most out of Gatsby!