title: Prevent Varnish to cache PHP code
body: <p>I'm working on a Wordpress project which uses Varnish cache server. Although my project is on Wordpress but I'm pretty sure that this issue will be on any other CSM &amp; framework too.</p>
  
  <p>In one of the template, I have just used Wordpress core function to get the user id of the currently logged in user like:</p>
  
  <pre><code>echo is get_current_user_id();
  </code></pre>
  
  <p>The problem is because of the Varnish, it gives 0 but as soon as I disable Varnish it works perfectly.</p>
  
  <p>So how to stop Varnish to stop caching PHP code?</p>
  
  <p>Note: I'm totally new to the Varnish.</p>
  
  <p>Thanks</p>