d daedalus

Ruby

Building a Ruby App

daedalus supports Ruby apps with or without Bundler. It detects a Ruby project by the presence of a Gemfile or a single .rb file.

Detection

File Strategy
Gemfile Bundler — uses vendor/bundle/ or .bundle/config for gem paths
Single *.rb Embeds Ruby interpreter, no dependency resolution

Prerequisites

  • Ruby installed (ruby on PATH)
  • For Bundler projects: run bundle install before building

Build

# Bundler project
daedalus build ./my-ruby-app -o my-ruby-app.de

# Single file
daedalus build ./my-script -o my-script.de

The builder:

  1. detects the ruby runtime;
  2. for Bundler projects, reads GEM_PATH from .bundle/config or vendor/bundle/;
  3. embeds the ruby interpreter and its shared libraries;
  4. packages gems into the app layer;
  5. compresses and assembles the .de.

Entrypoint detection

The builder looks for a main script in this order:

  1. main.rb
  2. app.rb
  3. server.rb
  4. config.ru (Rack)
  5. config/ru (Rails convention)
  6. Rakefile

If none found, defaults to main.rb.

Bundler projects

cd my-ruby-app
bundle install --deployment    # installs to vendor/bundle
daedalus build . -o my-app.de

The builder reads BUNDLE_PATH from .bundle/config and embeds the gem directory. At runtime, GEM_PATH is set to point to the embedded gems.

Rails apps

Rails projects are detected by the presence of config/ru. The builder uses config.ru as the entrypoint with config.ru (Rack-based startup).

cd my-rails-app
bundle install --deployment
daedalus build . -o my-rails-app.de

Environment variables

RAILS_ENV=production ./my-rails-app.de
PORT=3000 ./my-rails-app.de

Known limitations

  • Only Ruby MRI is supported (not JRuby, TruffleRuby, or mruby).
  • Native C extensions (gems with .so files) require their system dependencies to be available on the build machine. The ELF analyzer resolves these.
  • Rails asset pipeline compilation must happen before daedalus build.
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