How to Contribute ↑

Thank you for your interest in contributing to ruby.wasm! This document describes development setup and pointers for diving into this project.

Install dependencies ↑

$ git clone https://github.com/ruby/ruby.wasm --recursive
$ cd ruby.wasm
$ ./bin/setup
# Compile extension library
$ bundle exec rake compile
$ rake --tasks

Building and Testing {ruby-wasm-wasi} ↑

# Download a prebuilt Ruby release (if you don't need to re-build Ruby)
$ rake build:download_prebuilt

# Build Ruby (if you need to build Ruby by yourself)
$ rake build:head-wasm32-unknown-wasip1-full

# Build npm package
$ rake npm:ruby-head-wasm-wasip2:build
# Test npm package
$ rake npm:ruby-head-wasm-wasip2:check

If you need to re-build Ruby, please clean ./rubies directory, and run rake npm:ruby-head-wasm-wasi again.

Building CRuby from source ↑

If you want to build CRuby for WebAssembly from source yourself, follow the below instructions.

Warning If you just want to build npm packages, you don’t need to build CRuby from source. You can download a prebuilt Ruby release by rake build:download_prebuilt.

For WASI target ↑

You can build CRuby for WebAssembly/WASI on Linux (x86_64) or macOS (x86_64, arm64). For WASI target, dependencies are automatically downloaded on demand, so you don’t need to install them manually.

To select a build profile, see profiles section in README.

# Build only a specific combination of ruby version, profile, and target
$ rake build:head-wasm32-unknown-wasip1-full
# Clean up the build directory
$ rake build:head-wasm32-unknown-wasip1-full:clean
# Force to re-execute "make install"
$ rake build:head-wasm32-unknown-wasip1-full:remake

# Output is in the `rubies` directory
$ tree -L 3 rubies/head-wasm32-unknown-wasip1-full
rubies/head-wasm32-unknown-wasip1-full/
├── usr
│   └── local
│       ├── bin
│       ├── include
│       ├── lib
│       └── share

For Emscripten target ↑

To build CRuby for WebAssembly/Emscripten, you need to install Emscripten. Please follow the official instructions to install.

# Build only a specific combination of ruby version, profile, and target
$ rake build:head-wasm32-unknown-emscripten-full
# Output is in the `rubies` directory
$ tree -L 3 rubies/head-wasm32-unknown-emscripten-full
rubies/head-wasm32-unknown-emscripten-full
└── usr
    └── local
        ├── bin
        ├── include
        ├── lib
        └── share

Code Formatting ↑

This project uses multiple code formatters for each language. To format all files, run rake format. Please make sure to run this command before submitting a pull request.

Re-bindgen from .wit files ↑

If you update {*.wit}, which describe the interface of a WebAssembly module, either imported or exported, you need to re-generate glue code from *.wit.

To re-generate them, you need to install the Rust compiler rustc and Cargo, then run rake check:bindgen.

The rake task installs {wit-bindgen} on demand, then just execute it for each generated code

If you see missing executable: cargo, please make sure cargo is installed correctly in your PATH.

Release Process ↑

To bump up npm package version, please follow the below steps:

$ rake 'bump_version[0.6.0]'
$ git commit -m"Bump version to 0.6.0"
$ git tag 0.6.0
$ git push origin 0.6.0
# After GitHub Actions "Build gems" is done
# https://github.com/ruby/ruby.wasm/actions/workflows/build-gems.yml
$ gh run download <run-id>
$ for pkg in cross-gem-*/ruby_wasm-*; do gem push $pkg; done
$ gem build && gem push ruby_wasm-*.gem && rm ruby_wasm-*.gem
$ (cd packages/gems/js/ && gem build && gem push js-*.gem && rm js-*.gem)
$ rake bump_dev_version

Release Channels ↑

Each npm package in this project provides two release channels: latest and next. The latest channel is for stable releases, and next channel is for pre-release.

e.g. For {@ruby/wasm-wasi}

$ npm install --save @ruby/wasm-wasi@latest
# or if you want the nightly snapshot
$ npm install --save @ruby/wasm-wasi@next
# or you can specify the exact snapshot version
$ npm install --save @ruby/wasm-wasi@2.7.1-2025-01-23-a

Adding Support for a New Ruby Version ↑

When a new version of Ruby is released, the following steps need to be taken to add support for it in ruby.wasm:

  1. Update lib/ruby_wasm/cli.rb:

  2. Add a new entry in the build_source_aliases method for the new version

  3. Specify the tarball URL and required default extensions

  4. Update Rakefile:

  5. Add the new version to BUILD_SOURCES

  6. Add a new entry in NPM_PACKAGES for the new version

  7. Create a new npm package: "'console # Copy from head package $ cp -r packages/npm-packages/ruby-head-wasm-wasi packages/npm-packages/ruby-NEW.VERSION-wasm-wasi

# Update version references # - In package.json: Update name, version, and description # - In README.md: Update version references “‘ Note: Most of the package contents can be reused from the head package as is, since the JavaScript API and build configuration remain the same across versions.

  1. Update package-lock.json by npm install

  2. Update documentation:

  3. Update version references in README.md

  4. Update examples in docs/cheat_sheet.md

  5. Update the package list in packages/npm-packages/ruby-wasm-wasi/README.md

  6. Test the build: console $ rake build:NEW.VERSION-wasm32-unknown-wasip1-full $ rake npm:ruby-NEW.VERSION-wasm-wasi:build $ rake npm:ruby-NEW.VERSION-wasm-wasi:check

  7. Create a pull request with all the changes