Varnish Plugin

Varnish is an open source web cache accelerator. For more information visit varnish-cache.org.

Discovery

You must configure the Varnish plugin for the monitoring agent in order to monitor Varnish.

The services discovered are displayed on the Varnish Services page in the Resources menu. After you install the monitoring agent and configure the Varnish plugin on your instances, Stackdriver Monitoring populates the Varnish Services page with inventory and metrics.

Supported Varnish Versions

Varnish is monitored by a plugin that uses the libvarnish library to read statistics stored in memory from the varnish daemon. This library depends on the version of Varnish that you are running, and is not compatible across versions. Stackdriver Monitoring only supports the version of Varnish that is shipped by default with the following Linux distributions:

  • Red Hat Enterprise Linux 7.x, CentOS 7.x: Varnish 3.x
  • Red Hat Enterprise Linux 6.x, CentOS 6.x: Varnish 2.x
  • Ubuntu 16.04 Xenial: Varnish 4.x
  • Ubuntu 14.04 Trusty or Ubuntu 12.04 Precise: Varnish 3.x
  • Debian 9 (Stretch): Varnish 5.x (partial support)
  • Debian 8 (Jessie): Varnish 4.x
  • Debian 7 (Wheezy): Varnish 3.x

Configuring Stackdriver Monitoring to monitor Varnish

After you install the monitoring agent, use the following instructions to configure the Varnish plugin on your instances.

Prerequisites

The Varnish plugin requires version 5.5.0-315 or later of the monitoring agent. To update the agent, see Upgrading the agent.

Enabling the Varnish monitoring plugin

On your VM instance, download varnish.conf from the GitHub configuration repository and place it in the directory /opt/stackdriver/collectd/etc/collectd.d/:

(cd /opt/stackdriver/collectd/etc/collectd.d/ && curl -O https://raw.githubusercontent.com/Stackdriver/stackdriver-agent-service-configs/master/etc/collectd.d/varnish.conf)

After adding the configuration file, restart the monitoring agent by running the following command:

sudo service stackdriver-agent restart

Information on other plugin configuration options can be found at collectd.org.

What is monitored

The Varnish plugin monitors the following metrics:

  • Backend Connections
    • Success (count)
    • Failures (count)
    • Not attempted (count)
    • Recycled (count)
    • Reused (count)
    • Too many (count)
    • Unused (count)
    • Was closed (count)
  • Client Connections
    • Accepted (count)
    • Dropped (count)
    • Received (count)
  • Cache Statistics
    • Cache hits (count)
    • Cache misses (count)
    • Hit pass (count)

More information on these metrics can be found at varnish-cache.org.

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