build.gradle

buildscript {
  repositories {
    jcenter()
  }
  dependencies {
    classpath "com.github.jruby-gradle:jruby-gradle-jar-plugin:1.1.4"
  }
}

apply plugin: 'com.github.jruby-gradle.base'
apply plugin: 'com.github.jruby-gradle.jar'

repositories {
  jcenter()
}


dependencies {
  jrubyJar 'rubygems:rake:10.4.2'
}

configurations {
    jrubyExec.extendsFrom jrubyJar
}

jrubyJar {
    from('.') { include 'Rakefile' }
}

import com.github.jrubygradle.JRubyExec
task doIt(type: JRubyExec) {
    jrubyArgs "-e", "require 'rake';p Gem.loaded_specs['rake']"
}