Easy Edge Rails Deployment

I have mentioned my affinity for edge rails several times. First, I showed you how I pimp my local setup. Next, I showed you how to really get edgy and lastly, I showed you that sometimes it bites back. Yeah, that still stings a bit. Anyway…this isn’t as dramatically cool as the first two or as stingy as the last one but it’s handy so here you go. Throw this in the bottom of your deploy.rb capistrano recipe and you’ll have easy peasy edge rails deployment.

set :rails_version, 7514 unless variables[:rails_version]

task :after_update_code, :roles => :app do
  rails_path    = "/var/www/apps/shared/rails"
  export_path   = "#{rails_path}/rev_#{rails_version}"
  symlink_path  = "#{release_path}/vendor/rails"
  
  # if revision does not exist then create it
  puts "Checking if rails revision #{rails_version} exists, exporting if not..."
  sudo "test -d #{export_path} || svn export http://dev.rubyonrails.org/svn/rails/trunk/ #{export_path}/ -r #{rails_version}" unless File.exist?(export_path)
  
  # create symlink in vendor folder to revision
  puts "Symlinking #{export_path} to #{symlink_path}..."
  sudo "ln -sf #{export_path} #{symlink_path}"
end

This makes a few assumptions that you might not want to assume, but I’ll leave that up to you to change. The basic gist is: make sure we have a copy of the rails version on the server and then create a symlink to it in your apps vendor directory. Now, if some great feature or bug fix comes into edge rails that you can’t live without, simply change the rails_version capistrano variable and the next time you deploy your app will automatically have a shiny new rails version symlinked into it’s vendor. This is handy if you have multiple apps on a server as they can share the same rails version which takes up less space. Yay!

Also, if you want to diss the rails_version set in your deploy file, you can pass the version you want in from the command line with something like this (off the top of my head could be different): cap -S rails_version=####.

Anyone else do something similar or have suggestions for improving this?