So you’ve written a Rails app and you want to show it off to your boss at work because you know that it will impress them. Problem is that your company only uses Java and won’t consider it for their production environment if it can’t be deployed under a JVM. Let’s go:

1. Install JRuby http://jruby.org
2. Install the required gems for Ruby on Rails to work with JRuby

jgem install mongrel activerecord-jdbcsqlite3-adapter rails

3. Install the gems particular to your application

jruby -S rake gems:install

4. Update your database.xml file, prefixing your adapter with jdbc

development:
  adapter: jdbcsqlite3
  database: db/development.sqlite3
  pool: 5
  timeout: 5000

5. Start your JVM

jruby script/server

6. Demonstrate
7. Sit back and wait for promotion

Some notes on whats going on above:

• Detailed installation instructions for JRuby can be found on their wiki: http://kenai.com/projects/jruby/pages/GettingStarted
• The jruby -S rake command is very important as the -S switch ensures that the rake command is sourced from the JRuby home, not the system path which would contain a native Ruby install
• ActiveRecord-JDBC can handle most any database you can think of in a corporate environment. Check it out here: http://kenai.com/projects/activerecord-jdbc/
• If you wish to use another database, there are some gems already pre-packaged, more details on the github page: http://github.com/nicksieger/activerecord-jdbc-adapter