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Varnish

Varnish

Plugin: go.d.plugin Module: varnish

Overview

This collector monitors Varnish instances, supporting both the open-source Varnish-Cache and the commercial Varnish-Plus.

It tracks key performance metrics, along with detailed statistics for Backends (VBE) and Storages (SMF, SMA, MSE).

It relies on the varnishstat CLI tool but avoids directly executing the binary. Instead, it utilizes ndsudo, a Netdata helper specifically designed to run privileged commands securely within the Netdata environment. This approach eliminates the need to use sudo, improving security and potentially simplifying permission management.

This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.

Default Behavior

Auto-Detection

Automatically detects and monitors Varnish instances running on the host or inside Docker containers.

Limits

The default configuration for this integration does not impose any limits on data collection.

Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.

Setup

Prerequisites

No action required.

Configuration

File

The configuration file name for this integration is go.d/varnish.conf.

You can edit the configuration file using the edit-config script from the Netdata config directory.

cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/varnish.conf

Options

The following options can be defined globally: update_every.

Name Description Default Required
update_every Data collection frequency. 10 no
timeout Timeout for executing the binary, specified in seconds. 2 no
instance_name Specifies the name of the Varnish instance to collect metrics from. This corresponds to the -n argument used with the varnishstat command. no
docker_container Specifies the name of the Docker container where the Varnish instance is running. If set, the varnishstat command will be executed within this container. no

Examples

Custom update_every

Allows you to override the default data collection interval.

jobs:
  - name: varnish
    update_every: 5

Metrics

Metrics grouped by scope.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.

Per Varnish instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

Metric Dimensions Unit
varnish.client_session_connections accepted, dropped connections/s
varnish.client_requests received requests/s
varnish.cache_hit_ratio_total hit, miss, hitpass, hitmiss percent
varnish.cache_hit_ratio_delta hit, miss, hitpass, hitmiss percent
varnish.cache_expired_objects expired objects/s
varnish.cache_lru_activity nuked, moved objects/s
varnish.threads threads threads
varnish.thread_management_activity created, failed, destroyed, limited threads/s
varnish.thread_queue_len queue_length threads
varnish.backends_requests sent requests/s
varnish.esi_parsing_issues errors, warnings issues/s
varnish.mgmt_process_uptime uptime seconds
varnish.child_process_uptime uptime seconds

Per Backend

These metrics refer to the Backend (VBE).

This scope has no labels.

Metrics:

Metric Dimensions Unit
varnish.backend_data_transfer req_header, req_body, resp_header, resp_body bytes/s

Per Storage

These metrics refer to the Storage (SMA, SMF, MSE).

This scope has no labels.

Metrics:

Metric Dimensions Unit
varnish.storage_space_usage free, used bytes
varnish.storage_allocated_objects allocated objects

Alerts

There are no alerts configured by default for this integration.

Troubleshooting

Debug Mode

Important: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

To troubleshoot issues with the varnish collector, run the go.d.plugin with the debug option enabled. The output should give you clues as to why the collector isn’t working.

  • Navigate to the plugins.d directory, usually at /usr/libexec/netdata/plugins.d/. If that’s not the case on your system, open netdata.conf and look for the plugins setting under [directories].

    cd /usr/libexec/netdata/plugins.d/
    
  • Switch to the netdata user.

    sudo -u netdata -s
    
  • Run the go.d.plugin to debug the collector:

    ./go.d.plugin -d -m varnish
    

Getting Logs

If you’re encountering problems with the varnish collector, follow these steps to retrieve logs and identify potential issues:

  • Run the command specific to your system (systemd, non-systemd, or Docker container).
  • Examine the output for any warnings or error messages that might indicate issues. These messages should provide clues about the root cause of the problem.

System with systemd

Use the following command to view logs generated since the last Netdata service restart:

journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep varnish

System without systemd

Locate the collector log file, typically at /var/log/netdata/collector.log, and use grep to filter for collector’s name:

grep varnish /var/log/netdata/collector.log

Note: This method shows logs from all restarts. Focus on the latest entries for troubleshooting current issues.

Docker Container

If your Netdata runs in a Docker container named “netdata” (replace if different), use this command:

docker logs netdata 2>&1 | grep varnish

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