In this nice blog entry is some description of how to make rails work with passenger on site5. As I liked to have Sinatra working for myself (and had the sinatra and rack gems installed locally), here is how it works for me:

• As usual with rails apps, have a symlink point from within $HOME/public_html to the public folder of your sinatra app.
• Create a .htaccess file in the same public directory, looking like

  PassengerEnabled on
  RackBaseURI /linkname
  

  which certainly means that you have to put in the name of the symlink
  

• Create a config.ru file in the app root

  ENV['GEM_PATH'] = "#{ENV['HOME']}/gems:/usr/lib/ruby/gems/1.8"
  ENV['GEM_HOME'] = "#{ENV['HOME']}/gems"
  
  require 'rubygems'
  require 'sinatra'
  
  set :env,  :production
  disable :run
  
  require 'app'
  

  The only significant change to a plain config.ru is the addition of the GEM_PATH at the very top of the file – this way your locally installed gems are being picked up by passenger

One more thing: it turned out to be a good idea to include the ENV['GEM_PATH'] = “#{ENV['HOME']}/gems:/usr/lib/ruby/gems/1.8″ line on top of the rails application file as well. Without that, starting a fresh passenger fork will cause an exception – it will however work on the second attempt. Will have to look into this …