gistfile1.rb

%w(app as).each do |role|
  desc "Adds #{role} to the target roles for the task"
  task(role) do
    if ENV['ROLES']
      ENV['ROLES'] += ",#{role}"
    else
      ENV['ROLES'] = role
    end
  end
end

desc "Executes the task as sudo"
task :use_sudo do
  ENV['SUDO'] = '1'
end

namespace :assets do
  namespace :assets do
    desc <<-DESC
      Run the asset precompilation rake task. You can specify the full path \
      to the rake executable by setting the rake variable. You can also \
      specify additional environment variables to pass to rake via the \
      asset_env variable. The defaults are:

        set :rake,      "rake"
        set :rails_env, "production"
        set :asset_env, "RAILS_GROUPS=assets"
    DESC
    task :precompile, roles: assets_role, except: { no_release: true } do
      from = source.next_revision(current_revision)
      cmd = "cd #{latest_release} && #{source.local.log(from)} vendor/assets/ app/assets/ | wc -l"
      assets_changed = capture(cmd).to_i > 0

      if releases.length <= 1 || assets_changed
        run %Q{cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:precompile}
      else
        logger.info "Skipping asset pre-compilation because there were no asset changes"
      end
    end
  end
end