capistrano 3 task to update robots.txt for staging

capistrano-robots.rb

  desc "Uploads a robots.txt that mandates the site as off-limits to crawlers"
  task :block_robots do
    content = [
      '# This is a staging site. Do not index.',
      'User-agent: *',
      'Disallow: /'
    ].join($/)
    on roles(:all) do
      within release_path do
        puts "Uploading blocking robots.txt"
        execute(:echo, "\"#{content}\" > public/robots.txt")
      end
    end
  end