Rack development server with instant reloading using Ruby::Box.
gem install rackup-box --clear-sources --source https://rubyelders.github.io/rackup-box --source https://gem.cooprun ->(env) { [200, {"content-type" => "text/plain"}, ["Hello World"]] }RUBY_BOX=1 rackup-box config.ruOpen http://localhost:9292, do a change in config.ru (like change Hello World to Hello Jimbo) and refresh the page.