If you are using varnish to cache the page in PHP and plan to exclude part of the page from being cached or control it then follow the steps below:

1. Extract the part of the page to be excluded from being cached to a separate file.

Let's assume you want time and date to be excluded from the cache. In this case create a separate php file as below:

 
// File name: timeDate.php

echo 'Accessed at :' . date('d M Y h:i:sa'); 

2.Include the page using esi tag.

 
<esi:include src="NoVarnishContent/timeDate" />
<!-- Use esi:remove tag to ensure page is still displayed if esi tag is not enabled! -->
<esi:remove>
    <div title="This is cached version:">
      <?php include _FILE_ROOT . '/app/views/partials/noVarnishContent/timeDate.php'; ?>
   </div>
</esi:remove>

2. Modify the Varnish (/etc/varnish/default.vcl) to enable esi

If you are using varnish above 3.0 then modify vcl_backend_rsponse as below:

 

sub vcl_backend_response {
    # Step 1: Enable ESI( Edge Side Scripting) to esi:include works
    set beresp.do_esi = true;

   # Step 2: Once we enable do_esi, we need to set ttl for the path that do not need caching. In this case we use wild card to include all the files that follows after NoVarnishContent
    if (bereq.url ~ "NoVarnishContent/*") {
        set beresp.ttl = 0s; # 0s means it won't be cached at all; can set 10s | 1m | 1h and so on
    } else { // for rest of the page
       set beresp.ttl = 30m;
    }
}