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Vijay Daswani
Vijay Daswani

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CKAD Exam Practice Exercise : Core Concepts

#kubernetes #developer #devops #cloud

Core Concepts (13%)

Practice questions based on these concepts

  • Understand Kubernetes API Primitives
  • Create and Configure Basic Pods

Exercise

List all the namespaces in the cluster


kubectl get namespaces

kubectl get ns
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List all the pods in all namespaces

kubectl get po --all-namespaces
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List all the pods in the particular namespace

kubectl get po -n <namespace name>
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List all the services in the particular namespace

kubectl get svc -n <namespace name>
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List all the pods showing name and namespace with a json path expression

kubectl get pods -o=jsonpath="{.items[*]['metadata.name', 'metadata.namespace']}"
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Create an rabbitmq pod in a default namespace and verify the pod running

// creating a pod
kubectl run rabbitmq --image=rabbitmq --restart=Never

// List the pod
kubectl get po
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Create the nginx pod with a yaml file

// get the yaml file with --dry-run flag
kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx-pod.yaml

// cat nginx-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

// create a pod 
kubectl create -f nginx-pod.yaml
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Output the yaml file of the pod you just created

kubectl get po nginx -o yaml
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Output the yaml file of the pod you just created without the cluster-specific information

kubectl get po nginx -o yaml --export
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Get the complete details of the pod you just created

kubectl describe pod nginx
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Delete the pod you just created

kubectl delete po nginx

kubectl delete -f nginx-pod.yaml
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Delete the pod you just created without any delay (force delete)

kubectl delete po nginx --grace-period=0 --force
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Create the nginx pod with version 1.17.4 and expose it on port 80

kubectl run nginx --image=nginx:1.17.4 --restart=Never --port=80
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Change the Image version to 1.15-alpine for the pod you just created and verify the image version is updated

kubectl set image pod/nginx nginx=nginx:1.15-alpine

kubectl describe po nginx

// another way it will open vi editor and change the version
kubeclt edit po nginx

kubectl describe po nginx
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Change the Image version back to 1.17.1 for the pod you just updated and observe the changes

kubectl set image pod/nginx nginx=nginx:1.17.1

kubectl describe po nginx

kubectl get po nginx -w # watch it
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Check the Image version without the describe command

kubectl get po nginx -o jsonpath='{.spec.containers[].image}{"\n"}'
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Create the nginx pod and execute the simple shell on the pod

// creating a pod
kubectl run nginx --image=nginx --restart=Never

// exec into the pod
kubectl exec -it nginx /bin/sh
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Get the IP Address of the pod you just created

kubectl get po nginx -o wide
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Create a busybox pod and run command ls while creating it and check the logs

kubectl run busybox --image=busybox --restart=Never -- ls

kubectl logs busybox
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If pod crashed check the previous logs of the pod

kubectl logs busybox -p
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Create a busybox pod with command sleep 3600

kubectl run busybox --image=busybox --restart=Never -- /bin/sh -c "sleep 3600"
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Check the connection of the nginx pod from the busybox pod

kubectl get po nginx -o wide

// check the connection
kubectl exec -it busybox -- wget -o- <IP Address>
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Create a busybox pod and echo message ‘How are you’ and delete it manually

kubectl run busybox --image=nginx --restart=Never -it -- echo "How are you"

kubectl delete po busybox
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Create a busybox pod and echo message ‘How are you’ and have it deleted immediately

// notice the --rm flag
kubectl run busybox --image=nginx --restart=Never -it --rm -- echo "How are you"
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Create an nginx pod and list the pod with different levels of verbosity

// create a pod
kubectl run nginx --image=nginx --restart=Never --port=80

// List the pod with different verbosity
kubectl get po nginx --v=7
kubectl get po nginx --v=8
kubectl get po nginx --v=9
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List the nginx pod with custom columns POD_NAME and POD_STATUS

kubectl get po -o=custom-columns="POD_NAME:.metadata.name, POD_STATUS:.status.containerStatuses[].state"
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List all the pods sorted by name

kubectl get pods --sort-by=.metadata.name
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List all the pods sorted by created timestamp

kubectl get pods--sort-by=.metadata.creationTimestamp
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Multi Container Pod Section based exercise to be continued in the next post.

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