Varnish Cache

Varnish Cache is an HTTP accelerator designed for dynamic, content-heavy websites as well as heavily consumed APIs.

Out-of-the-box metrics

Varnish Cache system performance metrics (CPU, memory, and more) are available with no additional configuration when using OneAgent on a server running Dynatrace OneAgent.

You also get details about network traffic, TCP requests, and connectivity, along with quality metrics such as retransmissions, round-trip time, and throughput.

Varnish Cache server metrics

Advanced Varnish Cache server metrics such as

  • Cache performance
  • Backend metrics
  • Client metrics
  • Thread metrics

are not available out of the box in Dynatrace.

If you want to make those metrics available in Dynatrace, you need to push them from varnishstat into Dynatrace. To learn how, see (GitHub link) Monitor Varnish Cache. The guide includes an example Python script demonstrating how to use the Varnish API to extract metrics values and the Dynatrace API to feed them into your monitoring environment.

Varnish Cache configuration for Real User Monitoring

Using a caching server with Dynatrace Real User Monitoring can sometimes lead to unexpected results. A cache hit rate close to zero is the most obvious symptom of cache-related problems.

Fortunately, with some caching-server configuration, it's usually possible to maintain a high cache hit rate while preserving Dynatrace monitoring coverage. For general caching server configuration information and an in-depth Varnish-specific example, see Configure your caching servers.