How to Use pnpm on Heroku

Summary

Heroku’s Node.js buildpack supports pnpm, a fast, disk-efficient alternative to npm, and early users reported 10–40% faster install times on Heroku deployments. pnpm uses a content-addressable store and symlinks to avoid duplicate packages, accelerates dependency installation by combining resolve, fetch, and linking, and enforces dependency boundaries. The tutorial uses Node.js v18 or higher and Corepack to initialize and pin pnpm 9, then creates an Express application whose pnpm-lock.yaml enables buildpack support and consistent package resolution. The demo server handles HTTP GET requests with “Hello pnpm!” and listens on process.env.PORT or defaults to 3000. It finishes by adding a Procfile, committing the project to Git, creating a Heroku app, and deploying with git push heroku main.

Takeaways

1. 1

   The Heroku Node.js buildpack requires pnpm-lock.yaml to enable pnpm support; the lockfile also keeps package resolution consistent and can allow resolution to be skipped for faster builds.

2. 2

   Corepack can initialize pnpm and pin an exact version, including an integrity signature, in package.json’s packageManager field for deterministic builds.

3. 3

   pnpm uses a content-addressable store and symlinks instead of duplicate package copies, while enforcing dependency boundaries against implicit transitive dependencies.