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# Varnish


<img src="https://netdata.cloud/img/varnish.svg" width="150"/>


Plugin: go.d.plugin
Module: varnish

<img src="https://img.shields.io/badge/maintained%20by-Netdata-%2300ab44" />

## 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`](https://varnish-cache.org/docs/trunk/reference/varnishstat.html) 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.


## 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.


## 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`](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#edit-a-configuration-file-using-edit-config) script from the
Netdata [config directory](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#the-netdata-config-directory).

```bash
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.


<details open><summary>Config options</summary>

| 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](https://varnish-cache.org/docs/trunk/reference/varnishstat.html) 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 |

</details>

#### Examples

##### Custom update_every

Allows you to override the default data collection interval.

```yaml
jobs:
  - name: varnish
    update_every: 5

```


## 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]`.

  ```bash
  cd /usr/libexec/netdata/plugins.d/
  ```

- Switch to the `netdata` user.

  ```bash
  sudo -u netdata -s
  ```

- Run the `go.d.plugin` to debug the collector:

  ```bash
  ./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:

```bash
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:

```bash
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:

```bash
docker logs netdata 2>&1 | grep varnish
```


