Verifying Github webhooks requests with Node.js

import type { ActionFunction } from '@remix-run/node'
import { json } from '@remix-run/node'
import crypto from 'crypto'

// The `loader` function handle the GET request to the route
// In this case, we are returning a 400 status, cause we only want to handle POST requests only
// See more about Remix route's loader here: https://remix.run/docs/en/route/loader
export let loader = () => {
  return json({ message: 'Bad request!' }, { status: 400 })
}

// The `action` function handle non-GET requests to the route
// See more about Remix route's action here: https://remix.run/docs/en/route/action
export let action: ActionFunction = async ({ request }) => {
  // Return a 405 status if the request method is not POST
  if (request.method !== 'POST') {
    return json({ message: 'Method not allowed' }, 405)
  }

  // Verify the webhook signature
  let signature = request.headers.get('X-Hub-Signature-256')
  let rawBody = await request.text()
  let webhookSecret = process.env.GITHUB_APP_WEBHOOK_SECRET
  let hmac = crypto.createHmac('sha256', webhookSecret)
  hmac.update(rawBody)
  let generatedSignature = `sha256=${hmac.digest('hex')}`
  if (signature !== generatedSignature) {
    return json({ message: 'Webhook must originate from GitHub!' }, 400)
  }

  let event = request.headers.get('X-GitHub-Event')
  console.log(`✅ Github webhook verified!. Event: "${event}"`)

  try {
    let payload = JSON.parse(rawBody)
    if (event === 'your_subscribed_event') {
      let { action, sender, ...rest } = payload
      // Do something with the payload from Github
      // `action` is the action that triggered the event
      // `sender` is the user that triggered the event
    }
    return json({ message: 'Webhook processed successfully!', event }, 200)
  } catch (err) {
    console.log(`❌ Error processing webhook: ${err?.toString()}`)
    // Return a 200 status to Github to avoid retries
    // even if the webhook payload is not processed successfully in your app
    return json({ message: 'Webhook processed!', event }, 200)
  }
}