metrics-server deployment tips

README.md

Using Geerlingguy's K8s cluster and trying to install the metrics-server has some little snowflakes, following is how they got solved for me.

Steps

• get the metrics server git clone https://github.com/kubernetes-sigs/metrics-server.git metrics-server
• label the nodes according to the metrics-server node affinity to ensure it works, original labelling was in my case beta.kubernetes.io/arch=amd64

kubectl label node master kubernetes.io/arch=amd64
kubectl label node node1  kubernetes.io/arch=amd64
kubectl label node node2  kubernetes.io/arch=amd64

• Fix the scrapping and allow inscecure tls by adding this the following command with the two options based on this answer and the ones above.

        command:
          - /metrics-server
          - --kubelet-insecure-tls
          - --kubelet-preferred-address-types=InternalIP,Hostname,InternalDNS,ExternalDNS,ExternalIP

just after those lines

      containers:
      - name: metrics-server
        image: k8s.gcr.io/metrics-server-amd64:v0.3.6

• Based on this answer, enable the hostnetwork by adding

      hostNetwork: true

just after those lines

    spec:
      serviceAccountName: metrics-server

Debugging

How I've done the debugging

• Inspect the nodes kubectl describe node node1
• Inspect the pod kubectl describe -n kube-system $(kubectl get po -n kube-system | grep metrics-server | \awk '{print $1;}') to get the affinity and the logs.
• Increase the logs by using max (10) verbosity, according to the README

        command:
          - /metrics-server
          - --v=10
          - --kubelet-insecure-tls
          - --kubelet-preferred-address-types=InternalIP,Hostname,InternalDNS,ExternalDNS,ExternalIP

• Run kubectl top pods or kubectl top nodes or kubectl get --raw /apis/metrics.k8s.io/v1beta1
• Run kubectl get apiservice v1beta1.metrics.k8s.io -o yaml to get further info about the APIService status, based on this answer.