JRuby-Enginize is a generator for Google AppEngine compliant JRuby applications. The generator currently supports Sinatra and Merb with more frameworks to come in the future. If you want to learn more about Google AppEngine, go to code.google.com/appengine and have a look at the tutorials. For more about JRuby, please go to www.codehaus.org and see what's up running Ruby applications on a Java VM.
The Google people work hard to make JRuby easier to deploy with each release of their tools, so don't blindly trust all those blog posts and samples you'll find but use the newest version of jruby-enginize and have a look at the Wiki page of the Google AppEngine JRuby tools (code.google.com/p/appengine-jruby/wiki/GettingStarted) to learn about the details beyond.
If you used JRuby-Enginize before, you will note two bigger changes:
There is no need for a separate JRuby installation anymore, as the google-appengine gem does that for you.
Gem handling changed as Google now uses bundler and all required gems have to be registered in a new file called “Gemfile”. These gems are loaded on the fly when you call “rake appengine:run” or “rake appengine:deploy”. Quite elegant…
These are the steps for installing the Google tools plus JRuby-Enginize running on top of it to streamline your first steps:
sudo gem sources -a http://gemcutter.org # Only needed once! sudo gem install google-appengine sudo gem install jruby-enginize
!!Warning: As Github cancelled gem support, we moved the gem from Github.com to Gemcutter.org. If you install from Github, you will not get the newest version! See gemcutter.org/gems/jruby-enginize for details.
You also need an Google AppEngine account to actually publish your code. Without account you can still play around with the tools and run applications locally.
JRuby-Enginize includes is a single executable named jruby-enginize which is inspired by the rails tool for generating Rails applications. So just call
and have a look at the options.
Here are the steps for creating and deploying a new Sinatra application:
Register with Google AppEngine and create a new application ID.
Generate your application with that new ID as directory name and the e-mail address of your Google account. Optionally choose a template (“sinatra” or “merb” for now).
jruby-enginize --email email@example.com --template sinatra jruby-enginize
Go to the new directory
Learn about the available rake tasks
Try out your application locally:
!!Attention: Whenever you want to require additional gems, be sure to add them to the bundler configuration in Gemfile instead of using jgem as the Google toole maintains a local repository per project and bundle the files to upload from that information.
Deploy the application:
The first time you deploy your application, you will be asked for e-mail and password to confirm your upload to the server.
You can repeat the deployment whenever you want. Be sure to set the version number in the AppEngine::Rack.configure_app part of config.ru to a new value, when you are experimenting with an unstable version and don't want to risk your users getting exceptions.
You can try the new version by opening e.g.
and replacing “3” with the version number you want to run.
Switch the application to the new version as default (stable version) by opening
and setting a new default available at
A small README with these and a few more application specific hints is generated along with the source code. Have fun.
Copyright © 2009 Holtzbrinck Digital GmbH, Jan Ulbrich
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