Ashish Sahni has posted instructions for packaging a Rails app as a WAR on his blog, based on the work of a number of JRuby community members. I ran through his instructions, and have only two modifications to make:

1. When installing Rails, you still probably want to pass --no-ri --no-rdoc since rdoc generation is still far too slow.
2. Because JRuby has a classloading bug (not loading from context classloader) you'll need to put the rails-integration JAR in glassfish/lib.

I was only able to get the "properties" page to display, at rails/info/properties. A separate page that used ActiveRecord didn't successfully execute...but it was close enough to taste.

So then, there's two important points you should get out of this:

Rails in a WAR file will happen...soon

This has always been our goal, with every improvement and fix we made to JRuby. The holy grail of Rails deployment would be to "zip it up and deploy it" like Java app developers can do with WAR files. And that goal is just around the corner, thanks to the JRuby community. That leads me to the second point:

The JRuby community is growing fast and doing great things

This is especially exciting to me. Tom and I are only two folks, even with full-time license to work on JRuby and related projects. The only way Ruby can be successful on the JVM is with community cooperation, and the work toward WAR deployment exemplifies what can happen.

I'd like to thank the folks on the JRuby-Extras project who have been working on this: Robert Egglestone, Chris Nelson, Fausto Lelli, and also Ashish Sahni at Sun who put together a great walkthrough.

Excellent work.