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CKA Exam notes

Important notes for CKA Exam:​

  • Don't forget to set context before each task
  • Copy + Paste is important (ctrl + shift + v | Shift + Insert)
  • Important Linux commands
    • kubectl logs >pod-name> | grep "abc" > /tmp/access-failed.txt
    • vim: "set paste" command

Possible Tasks​

Storage​

  • Create a StorageClass
  • Create a PersistentVolume
  • Create a PersistentVolumeClaim

Scheduling​

  • Applying affinity to pods
  • Applying taints to nodes
  • Applying tolerations to pods
  • Configuring and using autoscaling (VPA/HPA)

Security​

  • Enforce restricted pod security standard

Things to remember​

Dynamic env values​

spec:
  volumes:
    - name: shared-volume
      emptyDir: {}
  containers:
    - image: nginx:1-alpine
      name: mc-pod-1
      env:
        - name: NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName

Install a local package​

apt install ./cri-docker_0.3.16.3-0.debian.deb or dpkg -i ./cri-docker_0.3.16.3-0.debian.deb

Start service: systemctl start cri-docker
Start on boot: systemctl enable cri-docker

Upgrade existing helm chart​

  • List helm charts: helm list -n <namespace-name>
  • Update repos: helm repo update
  • Search repos: helm search repo <search-term>
  • Add repo: helm add repo <repo-name>
  • Upgrade repo: helm upgrade <release-name> <chart-name> --version <version-name> (Chart name is those from repo search)

Number of replicas wrong​

If after adjusting resource quota a deployment still has not the wanted number of replicas => Delete the associated replicaset

Create PersistentVolume on a specific node​

nodeAffinity has to be used to place the pv on a specific node

Enforce pod security standard​

Just follow the docs: Kubernetes Docs