Fix “error: Metrics API not available” in Kubernetes

Are you encountering the “error: Metrics API not available” after setting up Metrics Server in your Kubernetes cluster? Metrics Server is used in Kubernetes to collect resource usage data from pods and nodes in the cluster. The metrics collected are accessed centrally via the Kubernetes API, and this allows other cluster components and users to query resource usage in the cluster. The use case can be Horizontal Pod Autoscaling.

To resolve “error: Metrics API not available” in Kubernetes, let’s first uninstall Metrics server if you have it modified.

kubectl delete -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

Fix by patching the deployment

Install Metrics server by running the following commands:

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

Check metrics server deployment in yaml output:

kubectl -n kube-system get deployment metrics-server -o yaml        

We will patch the deployment to have the following settings:

• Add --kubelet-insecure-tls argument to containers args - used to skip verifying Kubelet CA certificates.
• Change the container port from 10250 to port 4443
• Add hostNetwork: true

Execute the commands to patch the deployment.

kubectl patch deployment metrics-server -n kube-system --type='json' -p='[{"op": "add","path": "/spec/template/spec/hostNetwork","value": true},{"op": "replace","path": "/spec/template/spec/containers/0/args","value": ["--cert-dir=/tmp","--secure-port=4443","--kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname","--kubelet-use-node-status-port","--metric-resolution=15s","--kubelet-insecure-tls"]},{"op": "replace","path": "/spec/template/spec/containers/0/ports/0/containerPort","value": 4443}]'

After some seconds the pod status should be running and active:

$ kubectl -n kube-system get pods -l k8s-app=metrics-server
NAME                              READY   STATUS    RESTARTS   AGE
metrics-server-58fb664478-n4rdj   1/1     Running   0          1m        

Check the metrics API status:

$ kubectl get apiservices -l k8s-app=metrics-server
NAME                     SERVICE                      AVAILABLE   AGE
v1beta1.metrics.k8s.io   kube-system/metrics-server   True        2m        

Test if the metrics server is running by checking your kubernetes nodes utilization

$ kubectl top nodes
NAME                 CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%
k8smas01.novalocal   183m         2%     2231Mi          16%
k8smas02.novalocal   376m         4%     1974Mi          14%
k8smas03.novalocal   289m         3%     1872Mi          13%