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#certification #certification-exam #cka #ckad #cncf #exam #exam-objectives #k8s #kubernetes #kubernetes-certified-administrator #kubernetes-cluster #kubernetes-native

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README

Kubernetes Certified Administration

Online resources that will help you prepare for taking the Kubernetes Certified Administrator Certification exam.

Disclaimer: This is not likely a comprehensive list as the exam will be a moving target with the fast pace of k8s development - please make a pull request if there something wrong, should be added, or updated.

I tried to restrict the cross references of resources to kubernetes.io. Youtube videos and other blog resources are optional; however, I still found them useful in my k8s learning journey.

Ensure you have the right version of Kubernetes documentation selected (e.g. v1.31 as of Oct 2024 exam) especially for API objects and annotations.

LDR: practice practice practice

Other CK exams:

CKA 2023 Exam Objectives

These are the exam objectives you review and understand in order to pass the test.

CNCF Exam Curriculum repository

Cluster Architecture, Installation, and Configuration 25%

Manage role based access control

- Lab: RBAC with Kubernetes in Minikube

Use kubeadm to install a basic cluster

- Lab: Install Kubernetes On Ubuntu

Manage a highly available Kubernetes cluster

- Options for Highly Available topology

Kubecon Europe 2020: Kubeadm deep dive

sample commands used during backup/restore/update of nodes

#etcd backup and restore brief export ETCDCTL_API=3 # needed to specify etcd api versions, not sure if it is needed anylonger with k8s 1.19+ etcdctl snapshot save -h #find save options etcdctl snapshot restore -h #find restore options ## possible example of save, options will change depending on cluster context, as TLS is used need to give ca,crt, and key paths etcdctl snapshot save /backup/snapshot.db --cert=/etc/kubernetes/pki/etcd/server.crt --key=/etc/kubernetes/pki/etcd/server.key -- cacert=/etc/kubernetes/pki/etcd/ca.crt # evicting pods/nodes and bringing back node back to cluster kubectl drain <node># to drain a node kubectl uncordon <node> # to return a node after updates back to the cluster from unscheduled state to Ready kubectl cordon <node> # to not schedule new pods on a node #backup/restore the cluster (e.g. the state of the cluster in etcd) # upgrade kubernetes worker node kubectl drain <node> apt-get upgrade -y kubeadm=<k8s-version-to-upgrade> apt-get upgrade -y kubelet=<k8s-version-to-upgrade> kubeadm upgrade node config --kubelet-version <k8s-version-to-upgrade> systemctl restart kubelet kubectl uncordon <node>

#kubeadm upgrade steps kubeadm upgrade plan kubeadm upgrade apply

Workloads & Scheduling – 15%

Understand deployments and how to perform rolling update and rollbacks
Use ConfigMaps and Secrets to configure applications

- configure a pod with a configmap - configure a pod with a secret

Know how to scale applications

- scaling a statefulset - scaling a replicaset

Understand the primitives used to create robust, self-healing, application deployments

- Replicaset - Deployments - Statefulsets - Daemonset

Understand how resource limits can affect Pod scheduling
Awareness of manifest management and common templating tools

* Kustomize - Kustomize Blog * manage kubernetes objects * Install service catalog using helm - Non-k8s.io resource: CNCF Kubecon video: An introduction to Helm - Bridget Kromhout, Microsoft & Marc Khouzam, City of Montreal - Non-k8s.io resource: External resource: templating-yaml-with-code

Services & Networking – 20%

Understand host networking configuration on the cluster nodes
Understand connectivity between Pods

- The concept of Pods networking

Understand ClusterIP, NodePort, LoadBalancer service types and endpoints

- service

Know how to use Ingress controllers and Ingress resources

- Ingress concepts)

- Kubernetes Networking Intro and Deep-Dive - Bowei Du & Tim Hockin, Google - Kubernetes and Networks: why is this so dang hard? - Kubecon Eu 2020 Tutorial: Communication Is Key - Understanding Kubernetes Networking - Jeff Poole, Vivint Smart Home

Storage – 10%

Understand storage classes, persistent volumes
Understand volume mode, access modes and reclaim policies for volumes
Understand persistent volume claims primitive
Know how to configure applications with persistent storage

StorageClass, PersistentVolume, and PersitentVolumeClaim examples

#### Storage Class example # #### Persistent Volume Claim example # kind: PersistentVolumeClaim apiVersion: v1 metadata: name: local-pvc spec: accessModes: - ReadWriteOnce storageClassName: local-storage-sc resources: requests: storage: 100Mi

## Persistent Volume example # apiVersion: v1 kind: PersistentVolume metadata: name: local-pv spec: accessModes: - ReadWriteOnce capacity: storage: 200Mi local: path: /data/pv/disk021 persistentVolumeReclaimPolicy: Retain storageClassName: local-storage-sc volumeMode: Filesystem ### Pod using the pvc # apiVersion: v1 kind: Pod metadata: name: nginx labels: name: nginx spec: containers: - name: nginx image: nginx volumeMounts: - name: local-persistent-storage mountPath: /var/www/html volumes: - name: local-persistent-storage persistentVolumeClaim: claimName: local-pvc

Troubleshooting – 30%

- Pending or termintated pods

- DNS troubleshooting

Tips:

practice practice practice

Get familiar with:

Familiarize yourself with the documentation, initially concepts and mostly tasks, kubectl explain command, kubectl cheatsheet, and kubectl commands reference

- https://kubernetes.io/docs/concepts/ - https://kubernetes.io/docs/tasks/ - https://kubernetes.io/docs/user-guide/kubectl-cheatsheet/ - https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands

kubectl api-versions and kubectl api-resources wih grep for a specific resoruce e.g. pv, pvc, deployment, storageclass, ..etc can help figure out the apiVersion, and kind combined with explain below will help in constructing the yaml manifest
kubectl explain --recursive to construct out any yaml manifest you need and find its specd and details

When using kubectl for investigations and troubleshooting utilize the wide output it gives your more details

$kubectl get pods -o wide  --show-labels  --all-namespaces      or      $kubectl get pods -o wide  --show-labels  -A     # -A is quicker than --all-namespaces

In kubectl utilize --all-namespaces or better -A to ensure deployments, pods, objects are on the right name space, and right desired state

for events and troubleshooting utilize kubectl describe if its pod/resource related and logs if it is application issue related

$kubectl describe pods <PODID>   # for pod, deployment, other k8s resource issues/events      $kubectl logs <PODID>            # for container/application issues like crash loops

fast with kubectl e.g. the '-o yaml' in conjuction with --dry-run=client allows you to create a manifest template from an imperative spec, combined with --edit it allows you to modify the object before creation

kubectl create service clusterip my-svc -o yaml --dry-run=client > /tmp/srv.yaml
kubectl create --edit -f /tmp/srv.yaml

use kubectl aliases to speed up and reduce typo errors, practice these alaises early at your work and study for the exam. some example aliases:

alias k='kubectl' alias kg='kubectl get' alias kgpo='kubectl get pod' alias kcpyd='kubectl create pod -o yaml --dry-run=client' alias ksysgpo='kubectl --namespace=kube-system get pod' alias kd='kubectl delete' alias kdf='kubectl delete -f' for quick deletes you can add --force --grace-period=0 Not sure if it is a good idea if you are in a production cluster alias krmgf='kubectl delete --grace-period 0 --force' alias kgsvcoyaml='kubectl get service -o=yaml' alias kgsvcwn='watch kubectl get service --namespace' alias kgsvcslwn='watch kubectl get service --show-labels --namespace'

#example usage of aliases krmgf nginx-8jk71 # kill pod nginx-8jk71 using grace period 0 and force

Enable kubectl autocomplete. Autocomplete is the life saviour in any timebound exam as well as our day to day work (e.g. If autocomplete enabled k -n [Press Tab] will suggest available namespaces). Example command to enable autocomplete is available at official kubectl Cheat Sheet page, you don't have to remember anything.

source <(kubectl completion bash) # setup autocomplete in bash into the current shell, bash-completion package should be installed first. echo "source <(kubectl completion bash)" >> ~/.bashrc # add autocomplete permanently to your bash shell.
alias k=kubectl complete -F _startkubectl k