container.training/slides/k8s/metrics-server.md

Checking pod and node resource usage

• Since Kubernetes 1.8, metrics are collected by the core metrics pipeline

• The core metrics pipeline is:

  • optional (Kubernetes can function without it)

  • necessary for some features (like the Horizontal Pod Autoscaler)

  • exposed through the Kubernetes API using the aggregation layer

  • usually implemented by the "metrics server"

---

How to know if the metrics server is running?

• The easiest way to know is to run kubectl top

.exercise[

• Check if the core metrics pipeline is available:

  kubectl top nodes
  

]

If it shows our nodes and their CPU and memory load, we're good!

---

Installing metrics server

• The metrics server doesn't have any particular requirements

  (it doesn't need persistence, as it doesn't store metrics)

• It has its own repository, kubernetes-incubator/metrics-server

• The repository comes with YAML files for deployment

• These files may not work on some clusters

  (e.g. if your node names are not in DNS)

• The container.training repository has a metrics-server.yaml file to help with that

  (we can kubectl apply -f that file if needed)

---

Showing container resource usage

• Once the metrics server is running, we can check container resource usage

.exercise[

• Show resource usage across all containers:

  kuebectl top pods --containers --all-namespaces
  

]

• We can also use selectors (-l app=...)