Multiple Rubies with a single Passenger

Until Phusion Passenger released version 4 you had to choose a single Ruby to run Passenger with and all applications running on it had to be written in that Ruby. That method is clean and ideal. Unfortunately when managing multiple legacy applications things can't always be so clean.

I was recently moving an old app (i.e. Ruby 1.8.7, Rails 2.x, Mongrel) to a new server but didn't have the time to upgrade the app to a 1.9/3.x version. Luckily after reading the updated Passenger documentation I discovered that as of 4.x, Passenger now allows for multiple versions of Ruby to run the same version of Passenger. To make this work:

• Install Passenger with Ruby on Apache the normal way:

  gem install passenger
  passenger-install-apache2-module

• And, following the directions, copy the directives to a global Passenger config (possibly in conf.d/passenger.conf or httpd.conf depending on your configuration):

  LoadModule passenger_module /home/myuser/.rvm/gems/ruby-1.9.3-p125/gems/passenger-4.0.2/libout/apache2/mod_passenger.so
  PassengerRoot /home/myuser/.rvm/gems/ruby-1.9.3-p125/gems/passenger-4.0.2
  PassengerDefaultRuby /home/myuser/.rvm/wrappers/ruby-1.9.3-p125/ruby

• PassengerDefaultRuby has to be defined at the global level, but the PassengerRuby directive now can be defined at any level (i.e. VirtualHost, Directory, Location, .htaccess). So I changed my VirtualHost for this app to the following:

  <VirtualHost *:443>
  …
      RailsBaseURI /myapp
      <Directory /apps/myapp>
        Options -MultiViews
        PassengerRuby /home/myuser/.rvm/wrappers/ruby-1.8.7-p371/ruby
      </Directory>
  …
  </VirtualHost>

  Notice the PassengerRuby directive. It defines Ruby 1.8.7 for this specific app. So, yes, Passenger 4 was installed with Ruby 1.9.3, but because the gem supports multiple Ruby versions this local definition allows it to work with this 1.8.7 app.

  Also notice the difference between RailsBaseURI for Rails 2.x apps and RackBaseURI for Rails 3.x apps.

Related Links

• Phusion Passenger