Support RubyGems / Bundler

[kateinoigakukun]

Demo

$ bundle init
Writing new Gemfile to /tmp/tmp.ZeVCP05HyB/Gemfile
$ bundle add ruby_wasm
$ bundle add rainbow
$ bundle exec rbwasm build -o ruby.wasm
(snip)
INFO: Packaging gem: rainbow-3.1.1
INFO: Packaging setup.rb: bundle/setup.rb
INFO: Size: 51.17 MB

$ cat <<EOS > app.rb
require "/bundle/setup"
require "rainbow"

puts Rainbow("Hello RubyGems").green + " with " + Rainbow("WebAssembly").underline.bright + "!"
EOS

$ wasmtime run --dir ./::/ ruby.wasm app.rb

What's Added

• exe/rbwasm: CLI tool to build .wasm file packaging gems.
  • It does the following steps:
    1. Configure CRuby to make rbconfig.rb
    2. Build extension libraries in gems specified in Gemfile
    3. Build CRuby and static-link extension libraries built in step b
    4. Package gem files by wasi-vfs.
  • The gem packaging scheme is similar to bundle install --standalone
    • rbwasm generates bundle/setup.rb as well as bundle install --standalone
    • But extension libraries are cross-compiled
• ext/ruby_wasm: An extension library to use wasi-vfs and wizer from Ruby.

What's Changed

• js library is now gemified: Moved under packages/gems/js
• *-js build profiles, which additionally link js extension, are now generalized as a RubyGems application.
  • packages/npm-packages/ruby-wasm-wasi/Gemfile specifies gems to package

TODO

• Allow to package user app source files: Introduce rbwasm pack command as an alias of wasi-vfs pack #361
• Support dynamic linking for extension libraries.
  • Currently rbwasm uses a custom ext library builder instead of RubyGems' one since RubyGems' builder always expects dynamic linking and mkmf does not support make install for static linking.
    With dynamic linking, I hope we can use RubyGems' ext builder.
  • Some gems with complex ext library like nokogiri does feature detection using ruby's C header files but they are not ready before make install of CRuby build. This problem will be solved by dynamic linking, which allows building ext library after make install of CRuby build.
• Publish pre-built ext/ruby_wasm extension as fat-gems
• Include pre-built rubies/ruby-3.3-wasm32-unknown-wasi-full.tar.gz in gem package
  • Users can use it without building CRuby if the given Gemfile does not include any extension library

[rubyFeedback]

Could we also add to the FAQ a few examples for gems that are supported? From the above I now know that rainbow gem is supported. I'd like a few more - does not have to mention EVERY gem, but, say, half a dozen (aka 6) gems that we could experiment with would be nice.

Also the example used bundler. Can we use "gem" too? If so, how? All my gems use a .gemspec file; I do not really use bundler myself so I am curious if I can avoid bundler (I am aware it is bundled via gem itself nowadays, but I still don't want to have to maintain any Gemfile from bundler, I am too happy with .gemspec since many years).