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Metrics server

Limited vCluster Tenancy Configuration Support

This feature is only available for the following:

Running the control plane as a container and the following worker node types:
  • Host Nodes

Install metrics server (inside vCluster)​

In case the above recommended method of getting metrics in vCluster using the metrics server proxy does not fulfill your requirements and you need a dedicated metrics server installation in the vCluster you can follow this section. Make sure the vCluster has access to the host clusters nodes.

Install the metrics server via the official method into the vCluster.

Wait until the metrics server has started. You should be now able to use kubectl top pods and kubectl top nodes within the vCluster:

kubectl top pods --all-namespaces
NAMESPACE     NAME                              CPU(cores)   MEMORY(bytes)
kube-system   coredns-854c77959c-q5878          3m           17Mi
kube-system   metrics-server-5fbdc54f8c-fgrqk   0m           6Mi

How does it work?​

By default, vCluster will create a service for each node that redirects incoming traffic from within the vCluster to the node kubelet to vCluster itself. This means that if workloads within the vCluster try to scrape node metrics the traffic reaches vCluster first. vCluster will redirect the incoming request to the host cluster, rewrite the response (pod names, pod namespaces etc) and return it to the requester.

Reuse host metrics server​

Create a vcluster.yaml with:

integrations:
  metricsServer:
    enabled: true
    nodes: true
    pods: true

Then create a vCluster with:

vcluster create host-metrics-vcluster -f vcluster.yaml

Then the metrics api should be available within the vCluster. This will obviously require a metrics server to be installed on the host cluster.

If your metrics server is not using the default kube-system/metrics-server service, you can also configure a custom one via:

integrations:
  metricsServer:
    enabled: true
    apiService:
      service:
        name: my-custom-metrics-server
        namespace: my-custom-namespace
        port: 443

If you are using network policies, you need to add the metrics server pod to the allowed rules that the control plane can communicate with:

policies:
  networkPolicy:
    extraControlPlaneRules:
      - to:
          - podSelector:
              matchLabels:
                k8s-app: metrics-server
            namespaceSelector:
              matchLabels:
                kubernetes.io/metadata.name: "my-metrics-server-namespace"

Config reference​

metricsServer required object ​

MetricsServer reuses the metrics server from the host cluster within the vCluster.

enabled required boolean false ​

Enabled signals the metrics server integration should be enabled.

apiService required object ​

APIService holds information about where to find the metrics-server service. Defaults to metrics-server/kube-system.

service required object ​

Service is a reference to the service for the API server.

name required string ​

Name is the name of the host service of the apiservice.

namespace required string ​

Namespace is the name of the host service of the apiservice.

port required integer ​

Port is the target port on the host service to connect to.

nodes required boolean true ​

Nodes defines if metrics-server nodes api should get proxied from host to virtual cluster.

pods required boolean true ​

Pods defines if metrics-server pods api should get proxied from host to virtual cluster.