Cluster Components

K8s does not offer monitoring out of the box for its components. Multiple solutions like Prometheus, datadog, etc can be integrated.

`metrics-server`

Altough not a part of the cluster by default, K8s provides to option to create a limited resource metrics pipeline/

This pipeline provides a limited set of metrics related to cluster components such as the HorizontalPodAutoscaler controller, as well as the kubectl top utility. These metrics are collected by the lightweight, short-term, in-memory metrics-server.

metrics-server discovers all nodes on the cluster and queries each node’s kubelet for CPU and memory usage. The agent then pulls the information either from the underlying OS or using something like cAdvisor to pull pod (container specific metrics)

The metrics-server is a set of K8s components (Deployment, Service, etc) that can be directly installed with:

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

By then, usage statistics can be seen with

kubectl top node
kubectl top pod

Attention

Metrics Server is meant only for autoscaling purposes. For example, don’t use it to forward metrics to monitoring solutions, or as a source of monitoring solution metrics. In such cases one can collect metrics from Kubelet /metrics/resource endpoint directly.