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FAQ.md

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Vertical Pod Autoscaler FAQ

  1. VPA restarts my pods but does not modify CPU or memory settings. Why?

First check that VPA admission controller is running correctly:

$ kubectl get pod -n kube-system | grep vpa-admission-controller

vpa-admission-controller-69645795dc-sm88s 1/1 Running 0 1m

Check the logs of admission controller:

$ kubectl logs -n kube-system vpa-admission-controller-69645795dc-sm88s

If the admission controller is up and running, but there is no indication of it actually processing created pods or VPA objects in the logs, the webhook is not registered correctly.

Check the output of:

$ kubectl describe mutatingWebhookConfiguration vpa-webhook-config

This should be correctly configured to point to VPA admission webhook service. Example:

Name:         vpa-webhook-config
Namespace:
Labels:       <none>
Annotations:  <none>
API Version:  admissionregistration.k8s.io/v1beta1
Kind:         MutatingWebhookConfiguration
Metadata:
  Creation Timestamp:  2019-01-18T15:44:42Z
  Generation:          1
  Resource Version:    1250
  Self Link:           /apis/admissionregistration.k8s.io/v1beta1/mutatingwebhookconfigurations/vpa-webhook-config
  UID:                 f8ccd13d-1b37-11e9-8906-42010a84002f
Webhooks:
  Client Config:
    Ca Bundle: <redacted>
    Service:
      Name:        vpa-webhook
      Namespace:   kube-system
  Failure Policy:  Ignore
  Name:            vpa.k8s.io
  Namespace Selector:
  Rules:
    API Groups:

    API Versions:
      v1
    Operations:
      CREATE
    Resources:
      pods
    API Groups:
      autoscaling.k8s.io
    API Versions:
      v1beta1
    Operations:
      CREATE
      UPDATE
    Resources:
      verticalpodautoscalers

If the webhook config doesn't exist, something got wrong with webhook registration for admission controller. Check the logs for more info.

From the above config following part defines the webhook service:

Service:
      Name:        vpa-webhook
      Namespace:   kube-system

Check that the service actually exists:

$ kubectl describe -n kube-system service vpa-webhook

Name:              vpa-webhook
Namespace:         kube-system
Labels:            <none>
Annotations:       <none>
Selector:          app=vpa-admission-controller
Type:              ClusterIP
IP:                <some_ip>
Port:              <unset>  443/TCP
TargetPort:        8000/TCP
Endpoints:         <some_endpoint>
Session Affinity:  None
Events:            <none>

You can also curl the service's endpoint from within the cluster to make sure it is serving.

Note: the commands will differ if you deploy VPA in a different namespace.

  1. How can I use Prometheus as a history provider for the VPA recommender?

Configure your prometheus to get metrics from cadvisor. Make sure that the metrics from the cadvisor have the label job=kubernetes-cadvisor

Set the flags --storage=prometheus and --prometheus-address=<your-prometheus-address> in the deployment for the VPA recommender. The args for the container should look something like this:

spec:
  containers:
  - args:
    - --v=4
    - --storage=prometheus
    - --prometheus-address=http://prometheus.default.svc.cluster.local:9090

In this example, prometheus is running in the default namespace.

Now deploy the VPA recommender and check the logs.

$ kubectl logs -n kube-system vpa-recommender-bb655b4b9-wk5x2

Here you should see the flags that you set for the VPA recommender and you should see: Initializing VPA from history provider

This means that the VPA recommender is now using prometheus as the history provider.