heroku_build.rb

    def tar(path)
      base_path = path.split("/")[0..-2].join("/")
      folder = path.split("/")[-1]
      if File.exist?(".gitignore")
        ok = system("/usr/bin/tar -C \"#{base_path}\" --exclude='.git' --exclude-from=.gitignore -cvzf \"#{tempfile}\" \"#{folder}\"")
      else
        ok = system("/usr/bin/tar -C \"#{base_path}\" -cvzf \"#{tempfile}\" \"#{folder}\"")
      end
      unless ok
        raise StandardError, $?
      end
      tempfile
    end