Varnish Docker images for Docksal

Varnish is an HTTP accelerator designed for content-heavy dynamic web sites as well as APIs.

This image(s) is part of the Docksal image library.

Versions

• docksal/varnish:4.1 (docksal/varnish:4.1-2.0)
• docksal/varnish:6.0 (docksal/varnish:6.0-2.0)
• docksal/varnish:6.1 (docksal/varnish:6.1-2.0, docksal/varnish:latest)

Image tag scheme: <software-version>[-<image-stability-tag>][-<flavor>]

Features

• Cache flushing using PURGE (individual pages) and BAN (cache tag based) requests
• VCL config settings via environment variables, as well as custom VCL config support
• BigPipe support

Environmental variables

• VARNISH_PORT - port Varnish binds to, default: 80
• VARNISH_BACKEND_HOST - backed-end IP/host, default: web
• VARNISH_BACKEND_PORT - backed-end port, default: 80
• VARNISH_CACHE_SIZE - cache size, default: 64M
• VARNISH_VARNISHD_PARAMS - extra parameters for varnishd.
• VARNISH_VARNISHNCSA_PARAMS - parameters for varnishncsa (logging).
• VARNISH_SECRET - allow the secret to be set for varnish.
• VARNISH_CACHE_TAGS_HEADER - Varnish cache header name for BAN's, default: Cache-Tags

Cache flushing

PURGE

Cache for a specific URL can be flushed using the PURGE HTTP method, example:

curl -X PURGE http://varnish.tests.docksal/node/1

BAN

Cache for a group of URLs can be flushed using the BAN HTTP method by passing a list of tags via a specific header.

The application has to provide the cache tags header value(s) in the response (e.g. Cache-Tags: node:1 term:2). These tags are then used to ban pages from Varnish cache (usually handled by the application using a module/library).

By default, Cache-Tags is used as the header to pass cache tags. The header name can be overridden via the VARNISH_CACHE_TAGS_HEADER environment variable.

Depending your application environment VARNISH_CACHE_TAGS_HEADER may need to be set to:

• Purge-Cache-Tags for use with Drupal's Purge module
• X-Acquia-Purge-Tags for use with Drupal's Acquia Purge module
• X-Cache-Tags for Symfony FOSHttpCache

Using BAN to manually flush cache by tag:

curl -X BAN http://varnish.tests.docksal/ -H "Cache-Tags: node:1"

VCL

To provide a custom VCL config mount it at /opt/default.vcl.

When used with Docksal, custom VCL is automatically loaded from .docksal/etc/varnish/default.vcl if one exists in the project codebase.