Varnish exporter for Prometheus

Scrapes the varnishstat -j JSON output on each Prometheus collect and exposes all reported metrics. Metrics with multiple backends or varnish defined identifiers (e.g. VBE.*.happy SMA.*.c_bytes LCK.*.creat) and other metrics with similar structure (e.g. MAIN.fetch_*) are combined under a single metric name with distinguishable labels. Varnish naming conventions are preserved as much as possible to be familiar to Varnish users when building queries, while trying to follow Prometheus conventions like lower casing and using _ separators at the same time.

Handles runtime Varnish changes like adding new backends via vlc reload. Removed backends are reported by varnishstat until Varnish is restarted.

Advanced users can use -n -N, they are passed to varnishstat.

The following versions of Varnish are known to work: 6.0.0, 5.2.1, 5.1.2, 4.1.1, 4.1.0, 4.0.3 and 3.0.5. Missing category groupings in 3.x like MAIN. are detected and added automatically for label names to be consistent across versions, assuming of course that the Varnish project does not remove/change the stats.

I won't make any backwards compatibility promises at this point. Your built queries can break on new versions if metric names or labels are refined. If you find bugs or have feature requests feel free to create issues or send PRs.

Installing and running

You can find the latest binary releases for linux, darwin, windows, freebsd, openbsd and netbsd from the GitHub releases page.

By default, the exporter listens on port 9131. See prometheus_varnish_exporter -h for available options.

To test that varnishstat is found on the host machine and to preview all exported metrics run

prometheus_varnish_exporter -test

Troubleshooting

Could not get hold of varnishd, is it running?

2020/12/18 20:22:33 [FATAL] Startup test: varnishstat scrape failed: exit status 1

The user running the exporter is missing permissions to access varnish services. To avoid using sudo see #62.

Docker

Scraping metrics from Varnish running in a docker container is possible since 1.4.1. Resolve your Varnish container name with docker ps and run the following. This will use docker exec <container-name> to execute varnishstat inside the specified container.

prometheus_varnish_exporter -docker-container-name <container_name>

I still don't have an easy, clear and user-friendly way of running this exporter in a docker container. For community efforts and solutions see this issue.

Images

Container images are built and published to our GHCR registry as part of the release process. Images are built for multiple architectures (amd64, arm64) and for the latest major Varnish/Vinyl versions.

The image tags are in the format <version>-varnish-<varnish-version>. For example 1.7.0-varnish-8.0.0.

ghcr.io/otto-de/prometheus-varnish-exporter

Grafana dashboards

The example dashboard is available in JSON format. Feel free to send PRs for additional dashboards or improvements to existing ones.

Varnish 4 and VCL UUIDs

Starting with version 1.2 backend and server labels are always set. For backend-related metrics and Varnish 4 the server tag will be set to the VCL UUIDs for that backend. Note that there might be multiple VCLs loaded at the same time and the server tag might not be meaningful in that case.

To aggregate all loaded VCLs into per-backend metric the following Prometheus recording rules are recommended:

backend:varnish_backend_bereq_bodybytes:sum = sum(varnish_backend_bereq_bodybytes) without (server)
backend:varnish_backend_bereq_hdrbytes:sum = sum(varnish_backend_bereq_hdrbytes) without (server)
backend:varnish_backend_beresp_bodybytes:sum = sum(varnish_backend_beresp_bodybytes) without (server)
backend:varnish_backend_beresp_hdrbytes:sum = sum(varnish_backend_beresp_hdrbytes) without (server)
backend:varnish_backend_conn:sum = sum(varnish_backend_conn) without (server)
backend:varnish_backend_happy:sum = sum(varnish_backend_happy) without (server)
backend:varnish_backend_pipe_hdrbytes:sum = sum(varnish_backend_pipe) without (server)
backend:varnish_backend_pipe_in:sum = sum(varnish_backend_pipe_in) without (server)
backend:varnish_backend_pipe_out:sum = sum(varnish_backend_pipe_out) without (server)
backend:varnish_backend_req:sum = sum(varnish_backend_req) without (server)

Build

One time setup

This repository uses Golang with go modules. The minimum required version is defined in go.mod, later version are supported as well. To install go, follow the upstream recommendations or use the Golang package provided by your distribution.

Development

# clone
git clone git@github.com:otto-de/prometheus_varnish_exporter.git
cd prometheus_varnish_exporter

# build binary to current directory
go build

# draft local release with cross compilation
goreleaser release --snapshot --clean

Release

Releases are done with goreleaser. Make sure you have it installed or use the GitHub Action for releases.

To create a new release via the GitHub Action workflow you will have to create a new git tag with is a valid semantic version.

1. Update CHANGELOG.md with the changes for the new version and commit the changes.
2. Create and push a new git tag:

   [!NOTE] Replace v1.7.0 with your desired version number.

   git tag v1.7.0
   git push origin v1.7.0

3. Check the Actions tab on GitHub for the release workflow to complete.

This will trigger the release workflow that will build and publish binaries to the GitHub releases and also build and publish docker images to the GHCR registry.