In Deploying and Running a Rails Application, direct deployment of a rails application to GlassFish Server has been described. Warbler provides an easier way to deploy a rails application to a Java application server.
Warbler is a Gem that makes WAR file out of a Rails, Merb, or Rack-based application. Warbler provides a minimal, flexible, Ruby-like way to bundle application files for deployment to a Java application server.
Warbler provides a set of out-of-the box defaults to allow most Rails applications to assemble and work without external Gem dependencies.
Warbler bundles JRuby and the JRuby-Rack Servlet adapter for dispatching requests to the application inside the Java application server, and assembles all jar files in the WARBLER_HOME/lib/ directory into the application.
To learn more about Warbler, see Warbler.