warbler is awesome -- it allows you to _easily_ make Ruby- on-Rails applications Jruby-ish, and war'd up to deploy in a container. Here are the instructions for setting this up under JBoss, but except for the last step, should run under any standard Java web container.

Here's the steps:

1) install jruby 2) install warbler

jruby --command gem install warbler

3) Do config

jruby --command warble config

This creates a file called config/warble.rb which can be used to add gems and other configuration goodness.

4) If you're going to use ActiveRecord-jdbc, then following these instructions:

Download ActiveRecord/JDBC.

Install ActiveRecord-jdbc:

jruby --command gem install /path/to/ActiveRecord-jdbc-0.5.gem

Add this gem to warble.rb:

config.gems << 'ActiveRecord-JDBC'
config.gems << 'jruby-openssl'     #not required makes other things 
easier

Add the following lines to environment.rb:

if RUBY_PLATFORM =~ /java/
  require 'rubygems'
  RAILS_CONNECTION_ADAPTERS = %w(jdbc)
end   

If you are connecting straight to a PostgreSQL database, you can just include the postgres-pr gem in your warble.rb file, and keep your database.yml file normal. If you are using JDBC, following the latest tips for that (it seems to change) for configuring database.yml. If you are using a JNDI connection, then specify it like this:

production:
  adapter: jdbc
  jndi: java:putyourjndipathhere

Configuring your datasource in JNDI is up to you :)

5) Warble it

jruby --command warble

5) Deploy it

cp yourfile.war /path/to/jboss/deploy

The only problem I have right now is that on every request it generates a warning message about having to close my connection for me. I'm not sure if that's a warble config thing or a Postgres thing or a JRuby thing or a JDBC thing.

I hope I didn't leave anything out :)</pre>