Database migrations with deployed JRuby WAR files

In my previous post Compiling Rails project for distribution in a WAR file with JRuby, I explained how to build a  WAR file from a Rails project to distribute on to systems that have a Java app server like Tomcat or Glassfish.  If you're running this in production, you're probably going to want to run database migrations after the WAR file is deployed.  Unfortunately this is not as straightforward as you might expect.  But it's not too difficult.  To run database migrations, you must first create a file in your project, config/warbler.rb with the following contents:

Then, add a file named script/db_migrate with the following contents:

Now, on the production system, after the WAR file has been deployed, from the root directory of your web app, run the command:

jruby -S ./script/db_migrate

If you're running in 1.9 mode, add --1.9 before the -S. This assumes that you have a jruby executable in your path somewhere on the server. There should be a way to run the JRuby that is bundled in the WAR file, but I have not spent enough time looking in to it to figure out how. Has anyone had success with this?