Varnish

This document describes how to configure your Google Kubernetes Engine deployment so that you can use Google Cloud Managed Service for Prometheus to collect metrics from Varnish. This document shows you how to do the following:

Set up the exporter for Varnish to report metrics.
Access a dashboard in Cloud Monitoring to view the metrics.
Configure alerting rules to monitor the metrics.

These instructions apply only if you are using managed collection with Managed Service for Prometheus. If you are using self-deployed collection, then see the source repository for the Varnish exporter for installation information.

These instructions are provided as an example and are expected to work in most Kubernetes environments. If you are having trouble installing an application or exporter due to restrictive security or organizational policies, then we recommend you consult open-source documentation for support.

For information about Varnish, see Varnish .

Prerequisites

To collect metrics from Varnish by using Managed Service for Prometheus and managed collection, your deployment must meet the following requirements:

Your cluster must be running Google Kubernetes Engine version 1.28.15-gke.2475000 or later.
You must be running Managed Service for Prometheus with managed collection enabled. For more information, see Get started with managed collection .
To use dashboards available in Cloud Monitoring for the Varnish integration, you must use prometheus_varnish_exporter version "1.6.1" or later.
For more information about available dashboards, see View dashboards .

The Varnish exporter scrapes the output of the varnishstat command. It requires process namespace sharing and access to the Varnish container's /var/lib/varnish directory.

The Varnish exporter is not published as a container image; you must build your own. The following example demonstrates how to build an exporter container image that contains the exporter and the varnishstat command.

  # Copyright 2024 Google LLC 
 # 
 # Licensed under the Apache License, Version 2.0 (the "License"); 
 # you may not use this file except in compliance with the License. 
 # You may obtain a copy of the License at 
 # 
 #     http://www.apache.org/licenses/LICENSE-2.0 
 # 
 # Unless required by applicable law or agreed to in writing, software 
 # distributed under the License is distributed on an "AS IS" BASIS, 
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 # See the License for the specific language governing permissions and 
 # limitations under the License. 
 FROM 
  
 debian:stable-slim 
  
 AS 
  
 stage 
 WORKDIR 
  
 /exporter 
 ADD 
  
https://github.com/jonnenauha/prometheus_varnish_exporter/releases/download/1.6.1/prometheus_varnish_exporter-1.6.1.linux-amd64.tar.gz  
/exporter/exporter.tar.gz RUN 
  
tar  
-xvf  
exporter.tar.gz RUN 
  
chmod  
+x  
/exporter/prometheus_varnish_exporter-1.6.1.linux-amd64/prometheus_varnish_exporter FROM 
  
 varnish:7.2.0 
 COPY 
  
--from = 
stage  
/exporter/prometheus_varnish_exporter-1.6.1.linux-amd64/prometheus_varnish_exporter  
/prometheus_varnish_exporter ENTRYPOINT 
  
 [ 
  
 "/prometheus_varnish_exporter" 
  
 ]

Install the Varnish exporter

We recommend that you install the Varnish exporter, prometheus_varnish_exporter , as a sidecar to your Varnish workload. For information about using sidecars, see Extended applications on Kubernetes with multi-container pods .

To install prometheus_varnish_exporter as a sidecar to Varnish, modify your Varnish configuration as shown in the following example:

  # Copyright 2023 Google LLC 
 # 
 # Licensed under the Apache License, Version 2.0 (the "License"); 
 # you may not use this file except in compliance with the License. 
 # You may obtain a copy of the License at 
 # 
 #     https://www.apache.org/licenses/LICENSE-2.0 
 # 
 # Unless required by applicable law or agreed to in writing, software 
 # distributed under the License is distributed on an "AS IS" BASIS, 
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 # See the License for the specific language governing permissions and 
 # limitations under the License. 
 apiVersion 
 : 
  
 apps 
 / 
 v1 
 kind 
 : 
  
 Deployment 
 metadata 
 : 
  
 name 
 : 
  
 varnish 
 spec 
 : 
  
 selector 
 : 
  
 matchLabels 
 : 
 + 
  
 app 
 . 
 kubernetes 
 . 
 io 
 / 
 name 
 : 
  
 varnish 
  
 template 
 : 
  
 metadata 
 : 
  
 name 
 : 
  
 varnish 
  
 labels 
 : 
 + 
  
 app 
 . 
 kubernetes 
 . 
 io 
 / 
 name 
 : 
  
 varnish 
  
 spec 
 : 
  
 containers 
 : 
  
 - 
  
 name 
 : 
  
 varnish 
  
 image 
 : 
  
 varnish 
 : 
 7.2 
 . 
 0 
 + 
  
 volumeMounts 
 : 
 + 
  
 - 
  
 name 
 : 
  
 shared 
 - 
 data 
 + 
  
 mountPath 
 : 
  
 / 
 var 
 / 
 lib 
 / 
 varnish 
 + 
  
 env 
 : 
 + 
  
 - 
  
 name 
 : 
  
 VARNISH_HTTP_PORT 
 + 
  
 value 
 : 
  
 "8080" 
 + 
  
 - 
  
 name 
 : 
  
 exporter 
 + 
  
 image 
 : 
  
< custom 
 - 
 docker 
 - 
 image 
> + 
  
 volumeMounts 
 : 
 + 
  
 - 
  
 name 
 : 
  
 shared 
 - 
 data 
 + 
  
 mountPath 
 : 
  
 / 
 var 
 / 
 lib 
 / 
 varnish 
 + 
  
 readOnly 
 : 
  
 true 
 + 
  
 ports 
 : 
 + 
  
 - 
  
 containerPort 
 : 
  
 9131 
 + 
  
 name 
 : 
  
 prometheus 
 + 
  
 volumes 
 : 
 + 
  
 - 
  
 name 
 : 
  
 shared 
 - 
 data 
 + 
  
 emptyDir 
 : 
  
 {} 
 + 
  
 shareProcessNamespace 
 : 
  
 true

You must add any lines preceded by the + symbol to your configuration.

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME 
-f FILE_NAME

You can also use Terraform to manage your configurations.

Define a PodMonitoring resource

For target discovery, the Managed Service for Prometheus Operator requires a PodMonitoring resource that corresponds to the Varnish exporter in the same namespace.

You can use the following PodMonitoring configuration:

  # Copyright 2023 Google LLC 
 # 
 # Licensed under the Apache License, Version 2.0 (the "License"); 
 # you may not use this file except in compliance with the License. 
 # You may obtain a copy of the License at 
 # 
 #     https://www.apache.org/licenses/LICENSE-2.0 
 # 
 # Unless required by applicable law or agreed to in writing, software 
 # distributed under the License is distributed on an "AS IS" BASIS, 
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 # See the License for the specific language governing permissions and 
 # limitations under the License. 
 apiVersion 
 : 
  
 monitoring.googleapis.com/v1 
 kind 
 : 
  
 PodMonitoring 
 metadata 
 : 
  
 name 
 : 
  
 varnish 
  
 labels 
 : 
  
 app.kubernetes.io/name 
 : 
  
 varnish 
  
 app.kubernetes.io/part-of 
 : 
  
 google-cloud-managed-prometheus 
 spec 
 : 
  
 endpoints 
 : 
  
 - 
  
 port 
 : 
  
 prometheus 
  
 scheme 
 : 
  
 http 
  
 interval 
 : 
  
 30s 
  
 path 
 : 
  
 /metrics 
  
 selector 
 : 
  
 matchLabels 
 : 
  
 app.kubernetes.io/name 
 : 
  
 varnish

Ensure that the label selectors and the port match the selectors and port used in Install the Varnish exporter .

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME 
-f FILE_NAME

You can also use Terraform to manage your configurations.

Define rules and alerts

You can use the following Rules configuration to define alerts on your Varnish metrics:

  # Copyright 2023 Google LLC 
 # 
 # Licensed under the Apache License, Version 2.0 (the "License"); 
 # you may not use this file except in compliance with the License. 
 # You may obtain a copy of the License at 
 # 
 #     https://www.apache.org/licenses/LICENSE-2.0 
 # 
 # Unless required by applicable law or agreed to in writing, software 
 # distributed under the License is distributed on an "AS IS" BASIS, 
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 # See the License for the specific language governing permissions and 
 # limitations under the License. 
 apiVersion 
 : 
  
 monitoring.googleapis.com/v1 
 kind 
 : 
  
 Rules 
 metadata 
 : 
  
 name 
 : 
  
 varnish-rules 
  
 labels 
 : 
  
 app.kubernetes.io/component 
 : 
  
 rules 
  
 app.kubernetes.io/name 
 : 
  
 varnish-rules 
  
 app.kubernetes.io/part-of 
 : 
  
 google-cloud-managed-prometheus 
 spec 
 : 
  
 groups 
 : 
  
 - 
  
 name 
 : 
  
 varnish 
  
 interval 
 : 
  
 30s 
  
 rules 
 : 
  
 - 
  
 alert 
 : 
  
 VarnishBackendConnectionFailure 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Varnish backend connection failure 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Varnish backend connection failure (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 varnish_backend_fail > 0 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 critical 
  
 - 
  
 alert 
 : 
  
 VarnishHighCacheEvictions 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Varnish high cache evictions 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Varnish high cache evictions (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 rate(varnish_main_n_obj_purged[5m]) >= 10 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 warning 
  
 - 
  
 alert 
 : 
  
 VarnishHighServerLimit 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Varnish high server limit 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Varnish high server limit (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 varnish_main_threads_failed > 0 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 critical 
  
 - 
  
 alert 
 : 
  
 VarnishSessionsDropped 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Varnish sessions dropped 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Varnish sessions dropped (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 varnish_main_sessions{type="dropped"} > 0 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 critical

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME 
-f FILE_NAME

You can also use Terraform to manage your configurations.

For more information about applying rules to your cluster, see Managed rule evaluation and alerting .

You can adjust the alert thresholds to suit your application.

Verify the configuration

You can use Metrics Explorer to verify that you correctly configured the Varnish exporter. It might take one or two minutes for Cloud Monitoring to ingest your metrics.

To verify the metrics are ingested, do the following:

In the Google Cloud console, go to the Metrics explorer page:

Go to Metrics explorer

If you use the search bar to find this page, then select the result whose subheading is Monitoring .
In the toolbar of the query-builder pane, select the button whose name is either MQL or PromQL .
Verify that PromQL is selected in the Language toggle. The language toggle is in the same toolbar that lets you format your query.

Enter and run the following query:

up{job="varnish", cluster=" CLUSTER_NAME 
", namespace=" NAMESPACE_NAME 
"}

View dashboards

The Cloud Monitoring integration includes the Varnish Prometheus Overview dashboard. Dashboards are automatically installed when you configure the integration. You can also view static previews of dashboards without installing the integration.

To view an installed dashboard, do the following:

In the Google Cloud console, go to the Dashboards page:

Go to Dashboards

If you use the search bar to find this page, then select the result whose subheading is Monitoring .
Select the Dashboard List tab.
Choose the Integrations category.
Click the name of the dashboard, for example, Varnish Prometheus Overview .

To view a static preview of the dashboard, do the following:

In the Google Cloud console, go to the Integrations page:

Go to Integrations

If you use the search bar to find this page, then select the result whose subheading is Monitoring .
Click the Kubernetes Engine deployment-platform filter.
Locate the Varnish integration and click View Details .
Select the Dashboards tab.

Troubleshooting

For information about troubleshooting metric ingestion problems, see Problems with collection from exporters in Troubleshooting ingestion-side problems .

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Prerequisites

Install the Varnish exporter

Define a PodMonitoring resource

Define rules and alerts

Verify the configuration

View dashboards

Troubleshooting

Varnish