Varnish Cache Plus



This is the administrator and developer manual for Varnish Cache Plus. Among other things, it contains the information on

  • how to install, configure and update Varnish Cache Plus
  • features available in Varnish Cache Plus and its related packages
  • how to tune Varnish Cache Plus for better performance
  • how to extend its capabilities through the use of Varnish Modules

The main audiences for this manual are systems administrators and managers looking into Varnish Enterprise for solving their caching needs and users that need to look up information on various Varnish Enterprise components.

This documentation is not a replacement for other resources where basic Varnish concepts are explained. For this we refer to The Varnish Book or other introductions to Varnish and VCL.

What is Varnish Cache Plus?

Varnish Cache Plus is a special version of Varnish Cache made by Varnish Software for paying customers. Its many extra features are described on these pages. In addition to this, paying customers also get access to other components in the Varnish Enterprise product, and support from Varnish Software engineers.

Versioning and release schedule

Varnish Cache Plus is versioned after the original Varnish Cache release it is based on, with an additional number indicating the patch level.

For example is the Varnish Cache Plus 4.1.2r1 release based on Varnish Cache 4.1.2, and it is the first release on top of that version.

Right now Varnish Software is focusing on developing Varnish Cache Plus 6.0.x, which builds on what is currently known as the stable version of Varnish Cache.

Varnish Cache Plus 4.1.x was marked End Of Life 1st of August 2022.

Immediate concerns like security updates are handled by our support function and will be handled outside the regular release schedule.

Varnish modules

Varnish Cache Plus contains a set of Varnish Modules (VMODs) that extends the functionality of Varnish.

Github link

Examples of modules available:

  • VMODs from the varnish-modules_ package, including cookie handling, header modifications, saintmode, tcp for connection throttling, variable support, request rate throttling, and advanced cache invalidation with softpurge and xkey.

  • HTTP (curl) client interface, memcached client, IP geolocation, hash functions (digest) functionality.

  • Dynamic backend support, runtime ACL creation, fast hash table support with timeouts, calendar and accounting functions for paywalls/metered access. (Varnish Enterprise only)

This list is not meant to be complete, but as a pointer to what is available. Other Varnish Enterprise components may package other VMODs that are documented elsewhere.

Legacy modules available:

boltsort (3.0) Fast sorting of request arguments for applications where GET arguments are not ordered by default. Improves cache hit rate.

ipcast (3.0) Match a string against an ACL in VCL. Only needed in Varnish 3.0, builtin functionality in 4.0 and newer.

See Installing Varnish VMODs.

Package repository

All software related to Varnish Cache Plus and modules is available in Redhat and Ubuntu package repositories.

These repositories are available on using a customer-specific token. For access credentials contact support.

Further reading