Rails 3 Development Setup for Ubuntu

This post describes the steps needed to set up a fresh Ubuntu installation so you can start playing with Rails 3 and contribute to it

Method
This method isn't the most conventional way of developing on Ubuntu (I do replace the Ubuntu-supplied RubyGems binaries, so that I can get the latest version, and get gem binaries on my path). It also is not the most secure method (you will create install a ton of packages and create some random users on your database servers). It's quite fast and effective for development, though.

I have tested the steps below on Ubuntu 10.04 (Lucid Lynx), and I have good reasons to believe that they will work on Ubuntu 9.04 (Karmic Koala) as well.

Start off by installing some Ubuntu packages:
sudo apt-get update; sudo apt-get dist-upgrade
sudo apt-get install ruby rubygems ri ruby-dev libopenssl-ruby build-essential mysql-client mysql-server libmysqlclient-dev postgresql postgresql-client libpq-dev sqlite3 libsqlite3-dev curl git-core git-completion git-doc git-gui

Override Ubuntu's crippled RubyGems with the proper version:

sudo gem install rubygems-update

gem env | grep 'EXECUTABLE DIRECTORY'

sudo `gem env | grep 'EXECUTABLE DIRECTORY' | ruby -e "puts gets.split(': ', 2).last"`/update_rubygems

Create the rails user in MySQL:

echo "GRANT ALL ON *.* TO 'rails'@'localhost';" | mysql -uroot

Create a superuser in PostgreSQL:

sudo -u postgres createuser --superuser $USER

echo "\\password $USER" | sudo -u postgres psql

Install rvm:

sudo gem install rvm

rvm-install

echo "if [[ -s /home/$USER/.rvm/scripts/rvm ]] ; then source /home/$USER/.rvm/scripts/rvm ; fi" | cat - /home/$USER/.bashrc > /home/$USER/.bashrc2
rm /home/$USER/.bashrc; mv /home/$USER/.bashrc2 /home/$USER/bashrc

Install the Rails-preferred VM and create a clean gem set:

rvm install 1.8.7

rvm use 1.8.7

rvm gemset create rails3

rvm gemset use rails3

gem install bundler mocha

Prepare to work on Rails (do this every time you start a shell):

rvm use 1.8.7

rvm gemset use rails3

Check out Rails and install its dependencies:

git clone git://github.com/rails/rails.git

cd rails

bundle install

rake mysql:build_databases

rake postgresql:build_databases

Run the Rails test suite. If it passes, your environment is all set up. 
rake  # This should be run in the rails directory.

If you want to create a test application, then you should install the gems from the edge Rails:
rake install  # This should be run in the rails directory.

Happy hacking!

Motivation
At one of Boston.rb's hackfests, Dan Pickett held a workshop on contributing to Rails 3. I think I was the only one in the room not using OS X, and I had to follow a slightly different sequence of steps to get my setup working. I figured it's nice to summarize all the steps for future reference.

Conclusion
Thank you for reading! I hope the post above has been helpful, and hope you'll have fun playing with Rails 3. I look forward to your comments and suggestions for improving the method outlined here.