Introduction

Uzumibi lets you write request handlers in Ruby for WebAssembly-based edge and serverless runtimes.

An Uzumibi application has three main parts:

1. Ruby application code, normally lib/app.rb
2. The mruby/edge runtime and Uzumibi framework, compiled into a Wasm module
3. A platform adapter that transfers requests, responses, and optional host services between the platform and Wasm

Ruby code is compiled to mruby bytecode during the application build. It is not loaded from the filesystem at request time.

Minimal application

class App < Uzumibi::Router
  get "/" do |req, res|
    res.return(
      200,
      { "content-type" => "text/plain" },
      "Hello from Uzumibi!\n"
    )
  end
end

$APP = App.new

Uzumibi::Router dispatches by HTTP method and path. A handler receives an Uzumibi::Request and Uzumibi::Response and mutates the response. Ending the handler with res is the conventional style.

What the CLI provides

The uzumibi CLI generates complete, platform-specific projects. The generated build and development commands differ by template; the CLI itself currently only provides the new command.

For Cloudflare Workers, the generated project uses pnpm and Wrangler:

uzumibi new --template cloudflare my-app
cd my-app
pnpm install
pnpm run dev

Continue with Installation and Getting Started, or see the Cloudflare Workers guide.