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

You can configure the varnish collector in two ways:

Method	Best for	How to
UI	Fast setup without editing files	Go to Nodes → Configure this node → Collectors → Jobs, search for varnish, then click + to add a job.
File	If you prefer configuring via file, or need to automate deployments (e.g., with Ansible)	Edit `go.d/varnish.conf` and add a job.

:::important

UI configuration requires paid Netdata Cloud plan.

:::

Prerequisites

No action required.

Configuration

Options

The following options can be defined globally: update_every.

Group	Option	Description	Default	Required
Collection	update_every	Data collection frequency.	10	no
	timeout	Timeout for executing the binary, specified in seconds.	2	no
Target	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

via UI

Configure the varnish collector from the Netdata web interface:

Go to Nodes.
Select the node where you want the varnish data-collection job to run and click the :gear: (Configure this node). That node will run the data collection.
The Collectors → Jobs view opens by default.
In the Search box, type varnish (or scroll the list) to locate the varnish collector.
Click the + next to the varnish collector to add a new job.
Fill in the job fields, then click Test to verify the configuration and Submit to save.
- Test runs the job with the provided settings and shows whether data can be collected.
- If it fails, an error message appears with details (for example, connection refused, timeout, or command execution errors), so you can adjust and retest.

via File

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

The file format is YAML. Generally, the structure is:

update_every: 1
autodetection_retry: 0
jobs:
  - name: some_name1
  - name: some_name2

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

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

To debug a specific job:

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

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

Industry

Technology

Use cases

Varnish

Varnish

Overview

Default Behavior

Auto-Detection

Limits

Performance Impact

Setup

Prerequisites

Configuration

Options

via UI

via File

Examples

Custom update_every

Metrics

Per Varnish instance

Per Backend

Per Storage

Alerts

Troubleshooting

Debug Mode

Getting Logs

System with systemd

System without systemd

Docker Container

The observability platform companies need to succeed