Jon Maddox has previously published on how to do automated PHP deployment with capistrano, but I thought an all-ruby solution that handles all the rollbacky goodness of standard Cap was in order.

The trick is to create your standard config/deploy.rb lookin deployment recipe (like this one), and in it you have to redefine the deploy and update_code tasks to read:

# Override deploy to prevent restarting
task :deploy do
  update # task from standard cap recipe
end

# Override update_code to remove Rails directories
task :update_code, :except => { :no_release => true } do
  on_rollback { delete release_path, :recursive => true }
  source.checkout(self)
  set_permissions
  @releases = nil
end

There’s nothing else that’s special; just add your normal set statements up the top, sprinkling after_ and before_ task callbacks as required. Now go ahead and deploy the sucker:

cap setup && cap deploy

If you’re wondering where you’d start looking to discover this sort of thing, all of Capistrano’s magic exists in its standard recipe in the capistrano gem’s lib directory. If you’re using Capistrano 1.4.0 and macports that path would be:

/opt/local/lib/ruby/gems/1.8/gems/capistrano-1.4.0/lib/capistrano/recipes/standard.rb