Rolling deploy task for Capistrano.

deploy.rb

#...

set :rolling_deploy_wait, 60

  # Rolling restart of application servers
  task :restart, :roles => [:app], :except => {:no_release => true}, :once => true do
    servers = find_servers_for_task(current_task)
    servers.each_with_index do |s, index|
      run "sleep #{index * rolling_deploy_wait}; \
            touch #{File.join(current_path,'tmp','restart.txt')}; \
            nohup curl localhost > /dev/null 2>&1 &", 
          :hosts => s.host
    end
  end

#...