Rails deployment with Vlad, Git and Passenger

Now that Capistrano is discontinued, Vlad (at GitHub) seems to be the new cool deployment tool on the block. It works nicely with other usual suspects like Git and Passenger and uses Rake instead of reinventing the wheel - so let’s have a closer look.

Getting started

First of you need to install the Vlad gem: $ sudo gem install vlad

In its current version (1.3.2) Vlads default options are deploying from a SVN repository to a cluster of mongrels, which is not exactly what we are after. We need to configure it to use Git and Passenger, so switch to your Rails project and add the following lines to the end of the Rakefile:

begin
  require 'vlad'
  Vlad.load :app => :passenger, :scm => :git
rescue LoadError
  puts 'Could not load Vlad'
end

Run $ rake -T vlad to verify that Rake and Vlad know each other.

Now it’s time to set up your deployment configuration. Configuring Vlad is very similar to Capistrano, most of the variables are the same, so that you can easily migrate if you where using Capistrano before. Here is a simple configuration file including a deployment recipe which I’m currently using:

set :user, "myuser"
set :domain, "my.domain.com"
set :application, "myapp"
set :deploy_to, "/var/www/#{application}"
set :repository, "git@github.com:#{user}/#{application}.git"

namespace :vlad do
  desc "Symlinks the configuration files"
  remote_task :symlink_config, :roles => :web do
    %w(application.yml database.yml).each do |file|
      run "ln -s #{shared_path}/config/#{file} #{current_path}/config/#{file}"
    end
  end

  desc "Full deployment cycle: Update, migrate, restart, cleanup"
  remote_task :deploy, :roles => :app do
    Rake::Task['vlad:update'].invoke
    Rake::Task['vlad:symlink_config'].invoke
    Rake::Task['vlad:migrate'].invoke
    Rake::Task['vlad:start_app'].invoke
    Rake::Task['vlad:cleanup'].invoke
  end
end

Gotchas

It took me a while to get everything up and running because I encountered permission problems while trying to access the application repository from my deployment server. If you are running $ rake vlad:update and experience Git errors like fetch-pack from '...' failed, turn to Jordan Elvers blog post about it - he explains how you can solve this by setting up SSH agent forwarding.

Advancing

Need to go further and setup a multistage deployment environment? Check out this post on the Engine Yard blog, they solved this problem already.