eZ Platform being built on top of Symfony, it uses standard HTTP cache headers. By default the Symfony reverse proxy, written in PHP, is used to handle cache, but it can be easily replaced with any other reverse proxy like Varnish.

Use of Varnish is a requirement for use in Clustering setup, for overview of clustering feature see Clustering. 

Prerequisites

Recommended VCL base files

For Varnish to work properly with eZ, you'll need to use one of the provided files as a basis:

Note: Http cache management is done with the help of FOSHttpCacheBundle. You may need to tweak your VCL further on according to FOSHttpCache documentation in order to use features supported by it.

Configure eZ Publish

Update your Virtual Host

On apache:

<VirthualHost *:80>
    # Configure your VirtualHost with rewrite rules and stuff
 
    # Force front controller NOT to use built-in reverse proxy.
    SetEnv USE_HTTP_CACHE 0
 
	# Configure IP of your Varnish server to be trusted proxy
    # Replace fake IP address below by your Varnish IP address
    SetEnv TRUSTED_PROXIES "193.22.44.22"
</VirtualHost>

On nginx:

fastcgi_param USE_HTTP_CACHE 0;
# Configure IP of your Varnish server to be trusted proxy
# Replace fake IP address below by your Varnish IP address
fastcgi_param TRUSTED_PROXIES "193.22.44.22";

Update YML configuration

ezpublish:
    http_cache:
        purge_type: http
 
    system:
        # Assuming that my_siteaccess_group your frontend AND backend siteaccesses
        my_siteaccess_group:
            http_cache:
                # Fill in your Varnish server(s) address(es).
                purge_servers: [http://my.varnish.server:6081]