by passcod

GitHub Readme.md

This is a Heroku buildpack for Neon with cargo, rustup, node, and npm, as well as build requirements. Features:

  • Saves and restores npm and cargo caches.
  • Uses the latest stable Rust and Node, or as specified.
  • Defaults to running npm start as the web process.

Specifying which versions to use

By default, this buildpack installs:

  • Rust stable
  • Node LTS
  • npm latest

However, you can specify exact versions or channels via the engines field of the package.json. You can specify exact versions, ranges (only for node and npm), or channel names.

Rust is installed with rustup, Node with [nave], npm installs itself.

"engines": {
  "node": "^8.0.0",
  "npm": "^5.0.3",
  "rust": "nightly"


For an example, see the test/neon-test application, which is also used to drive our CI tests.

This buildpack expects a Node application with a package.json and a native/Cargo.toml. It will run npm install in the root of the app, then set a default Procfile if none exist to run npm start. Neon builds should be hooked as normal through the scripts.install package.json key.

For non-Neon apps

It's also possible to use this buildpack to run normal non-Neon node apps. Why use this instead of the official Node buildpack? Perhaps a Neon component is possible in the future. Perhaps you like the caching and version behaviour of this buildpack. In any case, simply set engines.neon to false to disable both native/Cargo.toml detection and the Rust install. Everything else behaves the same.