I recently learned that the
GlassFish app server doesn't require you WAR a Rails project to deploy it. The linked article explains how to create a simple Rails app through JRuby and deploy it on GlassFish without requiring any of the Ruby gem libraries that can package Rails apps into WARs.
Here's
an example of deploying an existing Rails application, Redmine (a project management tool), without having to WAR the project.