heroku-buildpack-bun

Heroku buildpack for Bun.js - allows you to run Bun on Heroku.

Largely copied from the Deno buildpack and Node.js buildpack.

How to use

To add the buildpack to your Heroku app, visit the settings page for your app on Heroku, then under 'Buildpacks' add the URL https://github.com/jakeg/heroku-buildpack-bun.

You'll need a Procfile in the root folder of your app, with eg web: bun index.js in it.

Pin a certain Bun version with a runtime.bun.txt or runtime.txt with e.g. v1.0.7 in it.

Support scripts

This buildpack automatically runs the following bun commands and scripts if defined in package.json.

• install (bun install)
• heroku-prebuild (bun run heroku-prebuild)
• build (bun run build)
• heroku-postbuild (bun run heroku-postbuild)

Binding to correct port

Bind to env.PORT eg

import { env } from 'process'

const server = Bun.serve({
  port: env.PORT || 3000,
  fetch(request) {
    return new Response(`Welcome to Bun running on Heroku!`)
  },
})

console.log(`Listening on localhost:${server.port}`)

Potential issues

~Be aware that Heroku doesn't use a new enough version of the Linux kernel to support io_uring, which is needed for Bun.write(). Use node:fs.writeFile() instead.~ - this seems now to be fixed.

Use the Issues tab to report any issues.