Whew. That’s a long title. I am talking about taking an existing Rails application deployed with Apache and Mongrel and upgrading it to use Phusion Passenger and Ruby Enterprise Edition.
Here’s what I did.
Install Ruby Enterprise Edition
First, if you’re going to use Phusion Ruby Enterprise Edition (I wanted to because of the recent Ruby security problems) I recommend starting with that first. Installation is straight-forward and does not conflict with your existing Ruby installation.
It supposedly can pick up gems installed with your old copy of Ruby, but I couldn’t figure out how to get that to work, so I had to install some gems again. You do that like this:
sudo /opt/ruby-enterprise-1.8.6-20080709/bin/gem install gem-name
We vendor all our gems except for a few that require native compilation or I just plain can’t get working in the vendor directory. I had to install hpricot, mime-types, and image_science.
The reason to start with Ruby Enterprise Edition is that you’ll have to reconfigure Passenger to use it if it’s not installed already.
Install Passenger
Next, install Passenger. Again, this is straight-forward. However, make sure you install it with the Ruby Enterprise Edition binary.
sudo /opt/ruby-enterprise-1.8.6-20080709/bin/gem install passenger
Then build the Apache module. You may need to install the Apache development header files if they’re not already there.
sudo /opt/ruby-enterprise-1.8.6-20080709/bin/passenger-install-apache2-module
This will give you some lines of code to put in your httpd.conf file. Since you used Ruby Enterprise Edition to run the command, the PassengerRuby variable, the PassengerRoot, and the location of the mod_passenger.so will be inside your /opt/ruby-enterprise-X.X.X-YYYYMMDD directory tree.
Update Rails configuration
Now you need to remove mod_proxy_balancer and mod_rewrite from your application’s Apache config file. The DocumentRoot you had before ought to be fine—Passenger can detect when Apache is serving up a Rails application.
This is what I had in my config file before:
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# Configure mongrel_cluster
<Proxy balancer://tumblon_cluster>
BalancerMember http://127.0.0.1:8000
BalancerMember http://127.0.0.1:8001
</Proxy>
RewriteEngine On
# Prevent access to .svn directories
RewriteRule ^(.*/)?\.svn/ - [F,L]
ErrorDocument 403 "Access Forbidden"
# Check for asset hosts
RewriteRule %{REMOTE_HOST} ^assets\d.* [L]
# Check for maintenance file and redirect all requests
RewriteCond %{DOCUMENT_ROOT}/system/maintenance.html -f
RewriteCond %{SCRIPT_FILENAME} !maintenance.html
RewriteRule ^.*$ /system/maintenance.html [L]
# Rewrite index to check for static
RewriteRule ^/$ /index.html [QSA]
# Rewrite to check for Rails cached page
RewriteRule ^([^.]+)$ $1.html [QSA]
# Redirect all non-static requests to cluster
RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f
RewriteRule ^/(.*)$ balancer://tumblon_cluster%{REQUEST_URI} [P,QSA,L]
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Obviously, we are not using mod_proxy_balancer at all, so that can just go (also watch out for the last RewriteRule, wich uses the balancer).
The RewriteRules – for the most part – aren’t needed because Passenger handles cached pages automatically. Also, Passenger conflicts with mod_rewrite and turns it off by default, so they don’t work anyway.
I don’t have an alternative for the maintenance page, but I don’t use that anyway.
Bonus tip: Set your Rails environment. If you application runs in anything other than production, you need to set it here. I have a staging server that runs in its own environment, so I set it like so:
RailsEnv staging
Update Capistrano configuration
Only one more thing: update your deployment recipe. You don’t need to restart mongrel_cluster because there won’t be one.
I’m still in the dark ages using Capistrano 1.4.1, so this is the task I came up with:
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desc "Restart Phusion Passenger (restarts Apache)"
task :restart_app, :roles => :app do
sudo "#{apache_ctl} restart"
end
desc "Override the built-in restart task to restart Apache"
task :restart, :roles => :app do
restart_app
end
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Overriding restart is important because that’s what Capistrano will run. The default deprec version I was using restarted mongrel_cluster. This one restarts Apache.
You can restart Passenger by touching RAILS_ROOT/tmp/restart.txt but I prefer just to restart Apache.
And that’s about all there is to it.
