deploy_cleanup.rb

  desc <<-DESC
    Clean up old releases. By default, the last 5 releases are kept on each \
    server (though you can change this with the keep_releases variable). All \
    other deployed revisions are removed from the servers. By default, this \
    will use sudo to clean up the old releases, but if sudo is not available \
    for your environment, set the :use_sudo variable to false instead.
  DESC
  task :cleanup, :except => { :no_release => true } do
    count = fetch(:keep_releases, 5).to_i
    if count >= releases.length
      logger.important "no old releases to clean up"
    else
      logger.info "keeping #{count} of #{releases.length} deployed releases"

      directories = (releases - releases.last(count)).map { |release|
        File.join(releases_path, release) }.join(" ")

      try_sudo "rm -rf #{directories}"
    end
  end