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CKAD Exam Practice Exercise : Pod Design

vijaydaswani profile image Vijay Daswani ・8 min read

CKAD Exam : Practice Exercise (8 Part Series)

1) CKAD Exam : Practice Exercise 2) CKAD Exam Practice Exercise : Core Concepts 3 ... 6 3) CKAD Exam Practice Exercise : Multi Container Pods 4) CKAD Exam Practice Exercise : Pod Design 5) CKAD Exam Practice Exercise : State Persistence 6) CKAD Exam Practice Exercise : Configuration 7) CKAD Exam Practice Exercise : Observability 8) CKAD Exam Practice Exercise : Services and Networking

Pod Design (20%)

Practice questions based on these concepts

  • Understand how to use Labels, Selectors and Annotations
  • Understand Deployments and how to perform rolling updates
  • Understand Deployments and how to perform rollbacks
  • Understand Jobs and CronJobs

Questions

Get the pods with label information

kubectl get pods --show-labels

Create 5 nginx pods in which two of them is labeled env=prod and three of them is labeled env=dev

kubectl run nginx-dev1 --image=nginx --restart=Never --labels=env=dev
kubectl run nginx-dev2 --image=nginx --restart=Never --labels=env=dev
kubectl run nginx-dev3 --image=nginx --restart=Never --labels=env=dev
kubectl run nginx-prod1 --image=nginx --restart=Never --labels=env=prod
kubectl run nginx-prod2 --image=nginx --restart=Never --labels=env=prod

Verify all the pods are created with correct labels

kubeclt get pods --show-labels

Get the pods with label env=dev

kubectl get pods -l env=dev

Get the pods with label env=dev and also output the labels

kubectl get pods -l env=dev --show-labels

Get the pods with label env=prod

kubectl get pods -l env=prod

Get the pods with label env=prod and also output the labels

kubectl get pods -l env=prod --show-labels

Get the pods with label env

kubectl get pods -L env

Get the pods with labels env=dev and env=prod

kubectl get pods -l 'env in (dev,prod)'

Get the pods with labels env=dev and env=prod and output the labels as well

kubectl get pods -l 'env in (dev,prod)' --show-labels

Change the label for one of the pod to env=uat and list all the pods to verify

kubectl label pod/nginx-dev3 env=uat --overwrite

kubectl get pods --show-labels

Remove the labels for the pods that we created now and verify all the labels are removed

kubectl label pod nginx-dev{1..3} env-
kubectl label pod nginx-prod{1..2} env-

kubectl get po --show-labels

Let’s add the label app=nginx for all the pods and verify

kubectl label pod nginx-dev{1..3} app=nginx
kubectl label pod nginx-prod{1..2} app=nginx

kubectl get po --show-labels

Get all the nodes with labels (if using minikube you would get only master node)

kubectl get nodes --show-labels

Label the node (minikube if you are using) nodeName=nginxnode

kubectl label node minikube nodeName=nginxnode

Create a Pod that will be deployed on this node with the label nodeName=nginxnode

kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > pod.yaml

// add the nodeSelector like below and create the pod

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
spec:
  nodeSelector:
    nodeName: nginxnode
  containers:
  - image: nginx
    name: nginx
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

kubectl create -f pod.yaml

Verify the pod that it is scheduled with the node selector

kubectl describe po nginx | grep Node-Selectors

Verify the pod nginx that we just created has this label

kubectl describe po nginx | grep Labels

Annotate the pods with name=webapp

kubectl annotate pod nginx-dev{1..3} name=webapp
kubectl annotate pod nginx-prod{1..2} name=webapp

Verify the pods that have been annotated correctly

kubectl describe po nginx-dev{1..3} | grep -i annotations
kubectl describe po nginx-prod{1..2} | grep -i annotations

Remove the annotations on the pods and verify

kubectl annotate pod nginx-dev{1..3} name-
kubectl annotate pod nginx-prod{1..2} name-

kubectl describe po nginx-dev{1..3} | grep -i annotations
kubectl describe po nginx-prod{1..2} | grep -i annotations

Remove all the pods that we created so far

kubectl delete po --all

Create a deployment called webapp with image nginx with 5 replicas

kubectl create deploy webapp --image=nginx --dry-run -o yaml > webapp.yaml

// change the replicas to 5 in the yaml and create it

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: webapp
  name: webapp
spec:
  replicas: 5
  selector:
    matchLabels:
      app: webapp
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: webapp
    spec:
      containers:
      - image: nginx
        name: nginx
        resources: {}
status: {}

kubectl create -f webapp.yaml

Get the deployment you just created with labels

kubectl get deploy webapp --show-labels

Output the yaml file of the deployment you just created

kubectl get deploy webapp -o yaml

Get the pods of this deployment

// get the label of the deployment
kubectl get deploy --show-labels

// get the pods with that label
kubectl get pods -l app=webapp

Scale the deployment from 5 replicas to 20 replicas and verify

kubectl scale deploy webapp --replicas=20

kubectl get po -l app=webapp

Get the deployment rollout status

kubectl rollout status deploy webapp

Get the replicaset that created with this deployment

kubectl get rs -l app=webapp

Get the yaml of the replicaset and pods of this deployment

kubectl get rs -l app=webapp -o yaml

kubectl get po -l app=webapp -o yaml

Delete the deployment you just created and watch all the pods are also being deleted

kubectl delete deploy webapp

kubectl get po -l app=webapp -w

Create a deployment of webapp with image nginx:1.17.1 with container port 80 and verify the image version

kubectl create deploy webapp --image=nginx:1.17.1 --dry-run -o yaml > webapp.yaml

// add the port section and create the deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: webapp
  name: webapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: webapp
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: webapp
    spec:
      containers:
      - image: nginx:1.17.1
        name: nginx
        ports:
        - containerPort: 80
        resources: {}
status: {}

kubectl create -f webapp.yaml

// verify
kubectl describe deploy webapp | grep Image

Update the deployment with the image version 1.17.4 and verify

kubectl set image deploy/webapp nginx=nginx:1.17.4

kubectl describe deploy webapp | grep Image

Check the rollout history and make sure everything is ok after the update

kubectl rollout history deploy webapp

kubectl get deploy webapp --show-labels
kubectl get rs -l app=webapp
kubectl get po -l app=webapp

Undo the deployment to the previous version 1.17.1 and verify Image has the previous version

kubectl rollout undo deploy webapp

kubectl describe deploy webapp | grep Image

Update the deployment with the image version 1.16.1 and verify the image and also check the rollout history

kubectl set image deploy/webapp nginx=nginx:1.16.1

kubectl describe deploy webapp | grep Image

kubectl rollout history deploy webapp

Update the deployment to the Image 1.17.1 and verify everything is ok

kubectl rollout undo deploy webapp --to-revision=3

kubectl describe deploy webapp | grep Image

kubectl rollout status deploy webapp

Update the deployment with the wrong image version 1.100 and verify something is wrong with the deployment

kubectl set image deploy/webapp nginx=nginx:1.100

kubectl rollout status deploy webapp (still pending state)

kubectl get pods (ImagePullErr)

Undo the deployment with the previous version and verify everything is Ok

kubectl rollout undo deploy webapp
kubectl rollout status deploy webapp

kubectl get pods

Check the history of the specific revision of that deployment

kubectl rollout history deploy webapp --revision=7

Pause the rollout of the deployment

kubectl rollout pause deploy webapp

Update the deployment with the image version latest and check the history and verify nothing is going on

kubectl set image deploy/webapp nginx=nginx:latest

kubectl rollout history deploy webapp (No new revision)

Resume the rollout of the deployment

kubectl rollout resume deploy webapp

Check the rollout history and verify it has the new version

kubectl rollout history deploy webapp

kubectl rollout history deploy webapp --revision=9

Apply the autoscaling to this deployment with minimum 10 and maximum 20 replicas and target CPU of 85% and verify hpa is created and replicas are increased to 10 from 1

kubectl autoscale deploy webapp --min=10 --max=20 --cpu-percent=85

kubectl get hpa

kubectl get pod -l app=webapp

Clean the cluster by deleting deployment and hpa you just created

kubectl delete deploy webapp

kubectl delete hpa webapp

Create a Job with an image node which prints node version and also verifies there is a pod created for this job

kubectl create job nodeversion --image=node -- node -v

kubectl get job -w
kubectl get pod

Get the logs of the job just created

kubectl logs  // created from the job

Output the yaml file for the Job with the image busybox which echos “Hello I am from job”

kubectl create job hello-job --image=busybox --dry-run -o yaml -- echo "Hello I am from job"

Copy the above YAML file to hello-job.yaml file and create the job

kubectl create job hello-job --image=busybox --dry-run -o yaml -- echo "Hello I am from job" > hello-job.yaml

kubectl create -f hello-job.yaml

Verify the job and the associated pod is created and check the logs as well

kubectl get job
kubectl get po

kubectl logs hello-job-*

Delete the job we just created

kubectl delete job hello-job

Create the same job and make it run 10 times one after one

kubectl create job hello-job --image=busybox --dry-run -o yaml -- echo "Hello I am from job" > hello-job.yaml

// edit the yaml file to add completions: 10

apiVersion: batch/v1
kind: Job
metadata:
  creationTimestamp: null
  name: hello-job
spec:
  completions: 10
  template:
    metadata:
      creationTimestamp: null
    spec:
      containers:
      - command:
        - echo
        - Hello I am from job
        image: busybox
        name: hello-job
        resources: {}
      restartPolicy: Never
status: {}

kubectl create -f hello-job.yaml

Watch the job that runs 10 times one by one and verify 10 pods are created and delete those after it’s completed

kubectl get job -w
kubectl get po

kubectl delete job hello-job

Create the same job and make it run 10 times parallel

kubectl create job hello-job --image=busybox --dry-run -o yaml -- echo "Hello I am from job" > hello-job.yaml

// edit the yaml file to add parallelism: 10

apiVersion: batch/v1
kind: Job
metadata:
  creationTimestamp: null
  name: hello-job
spec:
  parallelism: 10
  template:
    metadata:
      creationTimestamp: null
    spec:
      containers:
      - command:
        - echo
        - Hello I am from job
        image: busybox
        name: hello-job
        resources: {}
      restartPolicy: Never
status: {}

kubectl create -f hello-job.yaml

Watch the job that runs 10 times parallelly and verify 10 pods are created and delete those after it’s completed

kubectl get job -w
kubectl get po

kubectl delete job hello-job

Create a Cronjob with busybox image that prints date and hello from kubernetes cluster message for every minute

kubectl create cronjob date-job --image=busybox --schedule="*/1 * * * *" -- bin/sh -c "date; echo Hello from kubernetes cluster"

Output the YAML file of the above cronjob

kubectl get cj date-job -o yaml

Verify that CronJob creating a separate job and pods for every minute to run and verify the logs of the pod

kubectl get job
kubectl get po

kubectl logs date-job--

Delete the CronJob and verify all the associated jobs and pods are also deleted

kubectl delete cj date-job

// verify pods and jobs
kubectl get po
kubectl get job

CKAD Exam : Practice Exercise (8 Part Series)

1) CKAD Exam : Practice Exercise 2) CKAD Exam Practice Exercise : Core Concepts 3 ... 6 3) CKAD Exam Practice Exercise : Multi Container Pods 4) CKAD Exam Practice Exercise : Pod Design 5) CKAD Exam Practice Exercise : State Persistence 6) CKAD Exam Practice Exercise : Configuration 7) CKAD Exam Practice Exercise : Observability 8) CKAD Exam Practice Exercise : Services and Networking

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Vijay Daswani

@vijaydaswani

Certified Kubernetes Application Developer, Certified Azure Solution Architect and Having 2+ years of experience in IT profession and product engineering.

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