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WebAssembly with Ruby

  • WebAssembly support for Ruby is good thanks to ruby.wasm.
  • ruby.wasm is a collection of WebAssembly ports of the CRuby. It enables running Ruby applications on WASI compatible WebAssembly runtimes.
  • It uses wasi-vfs to create a virtual filesystem layer for WASI.
  • Sockets and threads are not supported yet.

Install wasi-vfs and ruby.wasm

Install wasi-vfs and ruby.wasm following the instructions here:

The ruby.wasm installation guide explains how to run a Ruby application using wasmtime, but you can use Enarx as well.

Ruby code

Let's create a fibonacci example:

def FibonacciSequence( n )
return n if ( 0..1 ).include? n
( FibonacciSequence( n - 1 ) + FibonacciSequence( n - 2 ) )

puts "Ruby - Fibonacci sequence example"

if ARGV.length > 0
ARGV.each { |arg|
n = arg.to_i
puts "Fibonacci sequence number at index #{n} is #{FibonacciSequence(n)}"
puts "Enter a non-negative number:"
n = ARGF.gets.to_i
puts "Fibonacci sequence number at index #{n} is #{FibonacciSequence(n)}"

Access the Ruby codex repository for code samples, including the fibonacci example.

Save it to: head-wasm32-unknown-wasi-full/src/fibonacci.rb

Run with Enarx

To run this application with Enarx, we'll need to create an Enarx.toml file:

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

kind = "stdin"

kind = "stdout"

kind = "stderr"

Save it to: head-wasm32-unknown-wasi-full/Enarx.toml

Now run Enarx and pass the path of the TOML file with the command line option --wasmcfgfile Enarx.toml:

enarx run --wasmcfgfile Enarx.toml my-ruby-app.wasm