Using jruby-gradle to create a jruby+dependencies jar, and still have your application code live directly on the filesystem

steps.txt

Assuming that you're using jruby-gradle 1.0.3, you'll need to take these steps:

1. In your build.gradle, in addition to your gems dependencies, you'll need:

    jrubyJar {
      initScript runnable()
    }

    configurations {
      jrubyJar {
        extendsFrom gems
      }
    }

This will ensure that you end up with a runnable jar that uses org.jruby.mains.JarMain as the
Main-Class in META-INF/MANIFEST.MF, and that all your gem dependencies end up in the jar file.
Any jar dependencies need to be in the jrubyJar configuration, either directly or by creating
another configuration that jrubyJar will extend from in addition to the gems configuration.

After running ./gradlew jrubyJar to build your jar, you will end up with a jar file in the
build/lib directory in your project root.  That will be an executable jar that you can use with
the -jar java command line option to run jruby directly.  However, by default jruby will use
uri:classloader:// as the current directory, in order to find all of the gem and jar dependencies
that you have included in the jar file.  You'll need to override this with the -C option, giving it
the absolute path to your project root.  In addition, because you are changing this path, you will
need to set the JARS_LOCK environment variable to uri:classloader://Jars.lock, so that the
jar-dependencies gem knows to look in the jar file for that, instead of your project root.

An example java command to run a script in bin/ or your project root might looks like this:
JARS_LOCK=uri:classloader:// java -d64 -server -jar build/libs/your_project-jruby.jar \
  -C /var/www/your_project bin/server.rb