Ruby Enterprise Edition (REE) and Passenger is an idea setup for a VPS or a machine with a limited amount of memory. Both REE and Passenger are developed by Phusion and are tweaked to use about 33% less memory when used together. It’s a fairly simple process to set both up on Ubuntu (10.04 was used in this article). So, let’s begin. You’ll need some basic tools and libraries, necessary to build ruby. If you don’t have them then install them:

sudo apt-get install build-essential zlib1g-dev libssl-dev libreadline6-dev

Then we need to download and install REE:

wget http://rubyforge.org/frs/download.php/71096/ruby-enterprise-1.8.7-2010.02.tar.gz
tar xzf ruby-enterprise-1.8.7-2010.02.tar.gz
sudo ./ruby-enterprise-1.8.7-2010.02/installer

The installation will run and take some time.

After it completes you can install Rails 3, by running:

sudo gem install rails

I’m going to be using MySQL, so I’ll run through how to install that here. If you are using a different database then google for a way to install it.

sudo apt-get install mysql-server

Now we need to install the MySQL library to speed up database queries. MySQL2 gem is out and works with Rails 3, so I’ll install that. First, we need to take care of the dependencies.

sudo apt-get install libmysql-ruby libmysqlclient-dev

Now, the actual mysql2 gem installation:

gem install mysql2

Let’s install Passenger next. Since we already installed Ruby Enterprise Edition all we need to do is:

sudo /opt/ruby-enterprise-1.8.7-2010.02/bin/passenger-install-apache2-module

If you run the above command it will check to see if you are missing any required software.

In my case, on an empty Ubuntu install I needed to install apache2-prefork-dev, libapr1-dev, and libaprutil1-dev.

sudo apt-get install apache2-prefork-dev libapr1-dev libaprutil1-dev

Then, re-run the Passenger installation:

sudo /opt/ruby-enterprise-1.8.7-2010.02/bin/passenger-install-apache2-module

This installation should tell you to paste some lines into your Apache config file. However, the instructions are a bit outdated and I couldn’t get my system to work accordingly. Instead, I found that, this line

LoadModule passenger_module /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/gems/1.8/gems/passenger-2.2.15/ext/apache2/mod_passenger.so

must be put inside of /etc/apache2/mods-available/passenger.load file.

and inside of /etc/apache2/mods-available/passenger.conf put the following lines:

<IfModule passenger_module>
    PassengerRoot /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/gems/1.8/gems/passenger-2.2.15
    PassengerRuby /opt/ruby-enterprise-1.8.7-2010.02/bin/ruby
</IfModule>

Finally, you need to enable the necessary modules (rewrite and passenger), and restart Apache:

sudo a2enmod rewrite
sudo a2enmod passenger
sudo apache2ctl restart

At this point Passenger should be configured and all you need to do is deploy your Rails 3 app and configure it within Apache.
Generally your site’s configuration would be inside of /etc/apache2/sites-available/ (you can call the file mysite) and look something like this:

<VirtualHost *:80>
   ServerName mysite
   DocumentRoot /var/www/mysite/public
</VirtualHost>

You’ll also need to disable the default and enable your app:

sudo a2dissite default
sudo a2ensite mysite

Restart your apache again if needed.

Related posts:

1. Installing Rails 3 on Ubuntu 10.04 Lucid Lynx