Write a ‘flash’ helper 

[% IF flash %]
<div class="container">
  <div class="row">
    <div class="[% flash_span %]">
      <div class="alert alert-success">
        <button class="close" data-dismiss="alert">x</button>[% flash %]
      </div>
    </div>
  </div>
</div>
[% END %]