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WebAssembly with Ruby

Ruby WebAssembly


Beginning in Ruby 3.2 Preview 1, Ruby supports WebAssembly as an additional platform. As such, it does work with Enarx. For this Demo, you'll need to be using a Linux system.


  1. Download the pre-compiled Ruby Wasm file ("ruby-head-wasm32-unknown-wasi-full.tar.gz") from the Ruby.wasm releases page.
    • Decompress the file.
    • cd head-wasm32-unknown-wasi-full Change directory to the newly created directory.
    • mv usr/local/bin/ruby ruby.wasm
  2. Create a simple Ruby script. I used this: puts "Hello, Enarx!";puts RUBY_DESCRIPTION. This just says "Hello", but more importantly, shows the version information and platform of the Ruby interpreter. Let's create this file in a src/hello_enarx.rb inside the "head" directory from the prior step.
    • Test the script by running ruby src/hello_enarx.rb.
    • On my system, the version information includes "x86_64-linux-gnu".
  3. Next, download wasi-vfs (Wasi virtual filesystem) program. It's created by a member of the Ruby development team. Choose the file for your system (Linux, right??).
    • Decompress the file
    • Place the wasi-vfs binary somewhere in your $PATH. For me, it was in ~/bin/.
  4. Create the new Ruby wasm file by packing the script we wish to run, and the Ruby library of scripts.
    • wasi-vfs pack ruby.wasm --mapdir /usr::usr/ --mapdir /src::src/ -o ruby_full.wasm
    • Test that it works: wasmtime run ruby_full.wasm -- /src/hello_enarx.rb
    • This time, the version information includes "wasm32-wasi"!
    • Notice that the command to wasmtime includes a forward slash before "src". That's because we're referring to the script inside the virtual filesystem inside the Wasm file.
  5. Running with Enarx.
    • First, we'll need an Enarx.toml file. The first line contains the command line arguments. Since the first argument that Ruby (and most programs) expect is the name of the running program, we'll have two arguments: "ruby" and "/src/hello_enarx.rb". The value of the first argument doesn't matter; what does matter is the path to our script as the second argument. The leading slash points to the Ruby script inside the Wasm file.
    • To run Enarx, we'll pass the path of the Toml file with the command line option --wasmcfgfile Enarx.toml.

Ruby Enarx


args = ["ruby.wasm", "/src/hello_enarx.rb"]

kind = "stdin"

kind = "stdout"

kind = "stderr"


puts "Hello, Enarx!";puts RUBY_DESCRIPTION