Rails 2.3.5 on App Engine

We assumed Rails 2 would never work without rubygems, and we committed to gem bunlder for JRuby on App Engine, so we were waiting for Rails 3. Fortunately, Takeru Sasaki was able to patch the Rails 2.3.5 calls to rubygems, and now we have it working. Rails 2.3.5 currently spins up several seconds faster than Rails 3, and just a few seconds behind Sinatra.

Install the Development Environment

The gems for the development environment include a pre-release appengine-tools gem that provides a pre-release version of jruby-rack.

sudo gem install google-appengine
sudo gem install appengine-tools --pre

Install Rails 2.3.5 with required patches

Create a folder for your app

mkdir rails_app; cd rails_app

Download and run the setup script

curl -O http://appengine-jruby.googlecode.com/hg/demos/rails2/rails2_appengine.rb
ruby rails2_appengine.rb

Working with Your Rails App

Start development server

dev_appserver.rb .

Open local console

appcfg.rb run script/console

Publish to production

appcfg.rb update .

Support for generators

We disable rubygems in the development environment, and the generators from Rails 2 perform various Gem dependency checks that are too difficult to patch, so we run the generators from the MRI.

sudo gem install rails rails_datamapper
sudo gem install activerecord-nulldb-adapter

Generate a restful controller and add it to config/routes.rb

./script/generate scaffold article title:string summary:text url:string \
-f --skip-migration

Generate a model for DataMapper

./script/generate dm_model article title:string summary:text url:string \
-f --skip-migration --skip-timestamps

Add timestamps in the new format

class Article
  include DataMapper::Resource

  property :id, Serial
  property :title, String, :nullable => false
  property :summary, Text, :nullable => false
  timestamps :at
end

Unresolved Issues

When you use the form, you’ll find an error that needs to be patched.

compared with non class/module