Varnish

What is Varnish?

Varnish is an HTTP accelerator that caches responses in memory to serve repeat requests without hitting your app. In Laradock it sits behind Nginx: Nginx listens on 80/443 and forwards to Varnish, and Varnish forwards back to Nginx on port 81 (VARNISH_BACKEND_PORT). The shipped config was developed and tested for WordPress but likely works with other systems too; the approach is based on this Linode guide.

Start Varnish

Varnish must be built after Nginx, because its startup checks the domain's availability:

docker compose up -d nginx
docker compose up -d proxy

The service runs as two containers, proxy and proxy2, both defined in varnish/compose.yml.

Stop Varnish

docker compose stop proxy proxy2

Configuration

All settings live in varnish/defaults.env and can be overridden by adding the same line to your own .env:

Variable	Default	What it does
VARNISH_CONFIG	/etc/varnish/default.vcl	Path to the active VCL config inside the container.
VARNISH_PORT	6081	Port Varnish listens on.
VARNISHD_PARAMS	-p default_ttl=3600 -p default_grace=3600	Extra flags passed to varnishd.
VARNISH_PROXY1_CACHE_SIZE	128m	Cache size for the first proxy (proxy).
VARNISH_PROXY1_BACKEND_HOST	workspace	Domain/host the first proxy serves.
VARNISH_PROXY1_SERVER	SERVER1	Server label for the first proxy.
VARNISH_PROXY2_CACHE_SIZE	128m	Cache size for the second proxy (proxy2).
VARNISH_PROXY2_BACKEND_HOST	workspace	Domain/host the second proxy serves.
VARNISH_PROXY2_SERVER	SERVER2	Server label for the second proxy.

Configure a domain

1. Set your domain in VARNISH_PROXY1_BACKEND_HOST.
2. Update your Varnish config and add a matching Nginx config, using nginx/sites/laravel_varnish.conf.example as a starting point.
3. Rename default_wordpress.vcl to default.vcl to use the WordPress-tuned config instead of the older default.vcl.

Serve multiple domains

1. Add a second configuration section to .env:

   VARNISH_PROXY1_CACHE_SIZE=128m
   VARNISH_PROXY1_BACKEND_HOST=replace_with_your_domain.name
   VARNISH_PROXY1_SERVER=SERVER1

2. Add a matching service to varnish/compose.yml, modeled on proxy2:

   custom_proxy_name:
     container_name: custom_proxy_name
     build: ./varnish
     expose:
       - ${VARNISH_PORT}
     environment:
       - VARNISH_CONFIG=${VARNISH_CONFIG}
       - CACHE_SIZE=${VARNISH_PROXY2_CACHE_SIZE}
       - VARNISHD_PARAMS=${VARNISHD_PARAMS}
       - VARNISH_PORT=${VARNISH_PORT}
       - BACKEND_HOST=${VARNISH_PROXY2_BACKEND_HOST}
       - BACKEND_PORT=${VARNISH_BACKEND_PORT}
       - VARNISH_SERVER=${VARNISH_PROXY2_SERVER}
     ports:
       - "${VARNISH_PORT}:${VARNISH_PORT}"
     links:
       - workspace
     networks:
       - frontend

Purge and reload

• Purge cache: curl -X PURGE https://yourwebsite.com/
• Reload Varnish: docker container exec proxy varnishreload
• Reload Nginx: docker exec Nginx nginx -t then docker exec Nginx nginx -s reload

Allowed Varnish CLI commands inside the container: varnishadm, varnishd, varnishhist, varnishlog, varnishncsa, varnishreload, varnishstat, varnishtest, varnishtop.

Common issues

• Varnish container fails to build. It's expected to be built after Nginx is already up, since it checks the domain's availability at build/start time; run docker compose up -d nginx first.
• Stale content keeps being served. Purge the cache (curl -X PURGE ...) or reload Varnish (varnishreload) after deploying changes.
• Wrong backend served. Confirm VARNISH_PROXY1_BACKEND_HOST/VARNISH_PROXY2_BACKEND_HOST match the domain in the corresponding Nginx site config, and that you're using default_wordpress.vcl (renamed to default.vcl) if following the WordPress setup.

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Varnish sits in front of Nginx; for balancing across multiple Varnish instances see HAProxy. New to Laradock? Start with Getting Started.