This is a very simple example of creating a self-contained JRuby executable which runs an embedded Jetty web server.
If you want to try it out you'll need to be running JRuby and have Bundler installed. Then install the dependencies:
Create the executable WAR file with:
bundle exec rake war
And then to start the application running:
java -jar jruby-embedded-jetty.war
You can pass extra system properties at the command line too, For instance to change the port the application will run on and to enable jmx output you could use:
java -server -Dcom.sun.management.jmxremote -Djetty.port=8090 -jar jruby-embedded-jetty.war