Developer Guide - Vhost

Basics

Varnish Cache is a caching HTTP reverse proxy that speeds up your sites by storing the compressed Page Source in memory.
Static files like CSS, JS, and Images are NOT being stored in Varnish Cache because NGINX delivers them faster.

When you open your site, e.g., https://www.domain.com, the request goes to NGINX, where SSL/TLS gets terminated.
If the request is a static file like a Stylesheet, Javascript, or an Image, it gets delivered immediately by NGINX.
All other requests are forwarded to Varnish Cache (Port 6081).

If Varnish Cache has a cache entry for a request, the page source gets immediately returned from memory without being processed by PHP-FPM.

If no cache entry exists, the request gets forwarded by Varnish Cache to NGINX port 8080, where it gets processed by the PHP Application via PHP-FPM.

Vhost Explanation

The Vhost below is being used for WordPress/WooCommerce.

In line 1-14 a redirect for domain.com takes place. All requests from http and https are redirected via 301 to https://www.domain.com.

The static files like CSS, JS, and Images are delivered at line 84-92.
All other requests are going through the location /, line 66-82.

At line 67, you see the placeholder {{varnish_proxy_pass}}.

When Varnish Cache is disabled, the rendered value for this placeholder is:

proxy_pass http://127.0.0.1:8080;

When Varnish Cache is enabled, it uses the value of Varnish Server from the Varnish Cache Settings, e.g.,

proxy_pass http://127.0.0.1:6081;

Lines 48-64 are special for WordPress/WooCommerce.

All requests to /wp-admin/ and wp-login.php are bypassed, meaning they are NOT going through Varnish Cache; they are forwarded to port 8080 (see lines 99-134), where they get processed by the PHP Application via PHP-FPM.