练习环境： https://www.katacoda.com/courses/kubernetes/playground
CKAD考试大纲：
- Core Concepts (13%)
- Multi-Container Pods (10%)
- Pod Design (20%)
- State Persistence (8%)
- Configuration (18%)
- Observability (18%)
- Services and Networking (13%)
Core Concepts (13%)
Practice questions based on these concepts
- Understand Kubernetes API Primitives
- Create and Configure Basic Pods
1.List all the namespaces in the cluster
kubectl get namespaces kubectl get ns
2. List all the pods in all namespaces
kubectl get po --all-namespaces
3. List all the pods in the particular namespace
kubectl get po -n <namespace name>
4. List all the services in the particular namespace
kubectl get svc -n <namespace name>
5. List all the pods showing name and namespace with a json path expression
kubectl get pods -o=jsonpath="{.items[*]['metadata.name', 'metadata.namespace']}"
6. Create an nginx pod in a default namespace and verify the pod running
// creating a pod kubectl run nginx --image=nginx --restart=Never// List the pod kubectl get po
7. Create the same 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
8. Output the yaml file of the pod you just created
kubectl get po nginx -o yaml
9. Output the yaml file of the pod you just created without the cluster-specific information
kubectl get po nginx -o yaml --export
10. Get the complete details of the pod you just created
kubectl describe pod nginx
11. Delete the pod you just created
kubectl delete po nginx
kubectl delete -f nginx-pod.yaml
12. Delete the pod you just created without any delay (force delete)
kubectl delete po nginx --grace-period=0 --force
13. 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
14. 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
15. 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
16. Check the Image version without the describe command
kubectl get po nginx -o jsonpath='{.spec.containers[].image}{" "}'
17. 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
18. Get the IP Address of the pod you just created
kubectl get po nginx -o wide
19. 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
20. If pod crashed check the previous logs of the pod
kubectl logs busybox -p
21. Create a busybox pod with command sleep 3600
kubectl run busybox --image=busybox --restart=Never -- /bin/sh -c "sleep 3600"
22. 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>
23. 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
24. 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"
25. 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
26. 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"
27. List all the pods sorted by name
kubectl get pods --sort-by=.metadata.name
28. List all the pods sorted by created timestamp
kubectl get pods--sort-by=.metadata.creationTimestamp
Multi-Container Pods (10%)
Practice questions based on these concepts
- Understand multi-container pod design patterns (eg: ambassador, adaptor, sidecar)
29. Create a Pod with three busy box containers with commands “ls; sleep 3600;”, “echo Hello World; sleep 3600;” and “echo this is the third container; sleep 3600” respectively and check the status
// first create single container pod with dry run flag kubectl run busybox --image=busybox --restart=Never --dry-run -o yaml -- bin/sh -c "sleep 3600; ls" > multi-container.yaml// edit the pod to following yaml and create it kubectl create -f multi-container.yaml
kubectl get po busybox
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: busybox name: busybox spec: containers: - args: - bin/sh - -c - ls; sleep 3600 image: busybox name: busybox1 resources: {} - args: - bin/sh - -c - echo Hello world; sleep 3600 image: busybox name: busybox2 resources: {} - args: - bin/sh - -c - echo this is third container; sleep 3600 image: busybox name: busybox3 resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
30. Check the logs of each container that you just created
kubectl logs busybox -c busybox1 kubectl logs busybox -c busybox2 kubectl logs busybox -c busybox3
31. Check the previous logs of the second container busybox2 if any
kubectl logs busybox -c busybox2 --previous
32. Run command ls in the third container busybox3 of the above pod
kubectl exec busybox -c busybox3 -- ls
33. Show metrics of the above pod containers and puts them into the file.log and verify
kubectl top pod busybox --containers// putting them into file kubectl top pod busybox --containers > file.log cat file.log
34. Create a Pod with main container busybox and which executes this “while true; do echo ‘Hi I am from Main container’ >> /var/log/index.html; sleep 5; done” and with sidecar container with nginx image which exposes on port 80. Use emptyDir Volume and mount this volume on path /var/log for busybox and on path /usr/share/nginx/html for nginx container. Verify both containers are running.
// create an initial yaml file with this kubectl run multi-cont-pod --image=busbox --restart=Never --dry-run -o yaml > multi-container.yaml// edit the yml as below and create it kubectl create -f multi-container.yaml
kubectl get po multi-cont-pod
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: multi-cont-pod name: multi-cont-pod spec: volumes: - name: var-logs emptyDir: {} containers: - image: busybox command: ["/bin/sh"] args: ["-c", "while true; do echo 'Hi I am from Main container' >> /var/log/index.html; sleep 5;done"] name: main-container resources: {} volumeMounts: - name: var-logs mountPath: /var/log - image: nginx name: sidecar-container resources: {} ports: - containerPort: 80 volumeMounts: - name: var-logs mountPath: /usr/share/nginx/html dnsPolicy: ClusterFirst restartPolicy: Never status: {}
35. Exec into both containers and verify that main.txt exist and query the main.txt from sidecar container with curl localhost
// exec into main container kubectl exec -it multi-cont-pod -c main-container -- sh cat /var/log/main.txt// exec into sidecar container kubectl exec -it multi-cont-pod -c sidecar-container -- sh cat /usr/share/nginx/html/index.html// install curl and get default page kubectl exec -it multi-cont-pod -c sidecar-container -- sh # apt-get update && apt-get install -y curl # curl localhost
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
36. Get the pods with label information
kubectl get pods --show-labels
37. 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=devkubectl run nginx-prod1 --image=nginx --restart=Never --labels=env=prod kubectl run nginx-prod2 --image=nginx --restart=Never --labels=env=prod
38. Verify all the pods are created with correct labels
kubeclt get pods --show-labels
39. Get the pods with label env=dev
kubectl get pods -l env=dev
40. Get the pods with label env=dev and also output the labels
kubectl get pods -l env=dev --show-labels
41. Get the pods with label env=prod
kubectl get pods -l env=prod
42. Get the pods with label env=prod and also output the labels
kubectl get pods -l env=prod --show-labels
43. Get the pods with label env
kubectl get pods -L env
44. Get the pods with labels env=dev and env=prod
kubectl get pods -l 'env in (dev,prod)'
45. 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
46. 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
47. 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
48. 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
49. Get all the nodes with labels (if using minikube you would get only master node)
kubectl get nodes --show-labels
50. Label the node (minikube if you are using) nodeName=nginxnode
kubectl label node minikube nodeName=nginxnode
51. 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 kubectl create -f pod.yaml
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: {}
52. Verify the pod that it is scheduled with the node selector
kubectl describe po nginx | grep Node-Selectors
53. Verify the pod nginx that we just created has this label
kubectl describe po nginx | grep Labels
54. Annotate the pods with name=webapp
kubectl annotate pod nginx-dev{1..3} name=webapp
kubectl annotate pod nginx-prod{1..2} name=webapp
55. 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
56. 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
57. Remove all the pods that we created so far
kubectl delete po --all
58. 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 kubectl create -f webapp.yaml
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: {}
59. Get the deployment you just created with labels
kubectl get deploy webapp --show-labels
60. Output the yaml file of the deployment you just created
kubectl get deploy webapp -o yaml
61. 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
62. Scale the deployment from 5 replicas to 20 replicas and verify
kubectl scale deploy webapp --replicas=20
kubectl get po -l app=webapp
63. Get the deployment rollout status
kubectl rollout status deploy webapp
64. Get the replicaset that created with this deployment
kubectl get rs -l app=webapp
65. 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
66. 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
67. 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 kubectl create -f webapp.yaml// verify kubectl describe deploy webapp | grep Image
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: {}
68. 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
69. 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
70. 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
71. 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
72. 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 Imagekubectl rollout status deploy webapp
73. 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)
74. Undo the deployment with the previous version and verify everything is Ok
kubectl rollout undo deploy webapp kubectl rollout status deploy webappkubectl get pods
75. Check the history of the specific revision of that deployment
kubectl rollout history deploy webapp --revision=7
76. Pause the rollout of the deployment
kubectl rollout pause deploy webapp
77. 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)
78. Resume the rollout of the deployment
kubectl rollout resume deploy webapp
79. Check the rollout history and verify it has the new version
kubectl rollout history deploy webapp
kubectl rollout history deploy webapp --revision=9
80. 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 hpakubectl get pod -l app=webapp
81. Clean the cluster by deleting deployment and hpa you just created
kubectl delete deploy webapp
kubectl delete hpa webapp
82. 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 -vkubectl get job -w kubectl get pod
83. Get the logs of the job just created
kubectl logs <pod name> // created from the job
84.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"
85. 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
86. Verify the job and the associated pod is created and check the logs as well
kubectl get job kubectl get pokubectl logs hello-job-*
87. Delete the job we just created
kubectl delete job hello-job
88. 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 kubectl create -f hello-job.yaml
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: {}
89. 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 pokubectl delete job hello-job
90. 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 kubectl create -f hello-job.yaml
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: {}
91. 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 pokubectl delete job hello-job
92. 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"
93. Output the YAML file of the above cronjob
kubectl get cj date-job -o yaml
94. 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 pokubectl logs date-job-<jobid>-<pod>
95. 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
State Persistence (8%)
Practice questions based on these concepts
- Understand PersistentVolumeClaims for Storage
96. List Persistent Volumes in the cluster
kubectl get pv
97. Create a hostPath PersistentVolume named task-pv-volume with storage 10Gi, access modes ReadWriteOnce, storageClassName manual, and volume at /mnt/data and verify
kubectl create -f task-pv-volume.yaml kubectl get pv
apiVersion: v1 kind: PersistentVolume metadata: name: task-pv-volume labels: type: local spec: storageClassName: manual capacity: storage: 10Gi accessModes: - ReadWriteOnce hostPath: path: "/mnt/data"
98. Create a PersistentVolumeClaim of at least 3Gi storage and access mode ReadWriteOnce and verify status is Bound
kubectl create -f task-pv-claim.yaml
kubectl get pvc
apiVersion: v1 kind: PersistentVolumeClaim metadata: name: task-pv-claim spec: storageClassName: manual accessModes: - ReadWriteOnce resources: requests: storage: 3Gi
99. Delete persistent volume and PersistentVolumeClaim we just created
kubectl delete pvc task-pv-claim
kubectl delete pv task-pv-volume
100. Create a Pod with an image Redis and configure a volume that lasts for the lifetime of the Pod
// emptyDir is the volume that lasts for the life of the pod
kubectl create -f redis-storage.yaml
redis-storage.yaml
apiVersion: v1 kind: Pod metadata: name: redis spec: containers: - name: redis image: redis volumeMounts: - name: redis-storage mountPath: /data/redis volumes: - name: redis-storage emptyDir: {}
101. Exec into the above pod and create a file named file.txt with the text ‘This is called the file’ in the path /data/redis and open another tab and exec again with the same pod and verifies file exist in the same path.
// first terminal kubectl exec -it redis-storage /bin/sh cd /data/redis echo 'This is called the file' > file.txt//open another tab kubectl exec -it redis-storage /bin/sh cat /data/redis/file.txt
102. Delete the above pod and create again from the same yaml file and verifies there is no file.txt in the path /data/redis
kubectl delete pod rediskubectl create -f redis-storage.yaml kubectl exec -it redis-storage /bin/sh cat /data/redis/file.txt // file doesn't exist
103. Create PersistentVolume named task-pv-volume with storage 10Gi, access modes ReadWriteOnce, storageClassName manual, and volume at /mnt/data and Create a PersistentVolumeClaim of at least 3Gi storage and access mode ReadWriteOnce and verify status is Bound
kubectl create -f task-pv-volume.yaml kubectl create -f task-pv-claim.yaml
kubectl get pv kubectl get pvc
104. Create an nginx pod with containerPort 80 and with a PersistentVolumeClaim task-pv-claim and has a mouth path "/usr/share/nginx/html"
kubectl create -f task-pv-pod.yaml
apiVersion: v1 kind: Pod metadata: name: task-pv-pod spec: volumes: - name: task-pv-storage persistentVolumeClaim: claimName: task-pv-claim containers: - name: task-pv-container image: nginx ports: - containerPort: 80 name: "http-server" volumeMounts: - mountPath: "/usr/share/nginx/html" name: task-pv-storage
Configuration (18%)
Practice questions based on these concepts
- Understand ConfigMaps
- Understand SecurityContexts
- Define an application’s resource requirements
- Create & Consume Secrets
- Understand ServiceAccounts
105. List all the configmaps in the cluster
kubectl get cm or kubectl get configmap
106. Create a configmap called myconfigmap with literal value appname=myapp
kubectl create cm myconfigmap --from-literal=appname=myapp
107. Verify the configmap we just created has this data
// you will see under data kubectl get cm -o yaml or kubectl describe cm
108. delete the configmap myconfigmap we just created
kubectl delete cm myconfigmap
109. Create a file called config.txt with two values key1=value1 and key2=value2 and verify the file
cat >> config.txt << EOF key1=value1 key2=value2 EOFcat config.txt
110. Create a configmap named keyvalcfgmap and read data from the file config.txt and verify that configmap is created correctly
kubectl create cm keyvalcfgmap --from-file=config.txt
kubectl get cm keyvalcfgmap -o yaml
111. Create an nginx pod and load environment values from the above configmap keyvalcfgmap and exec into the pod and verify the environment variables and delete the pod
// first run this command to save the pod yml kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx-pod.yml// edit the yml to below file and create kubectl create -f nginx-pod.yml// verify kubectl exec -it nginx -- env
kubectl delete po nginx
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx resources: {} envFrom: - configMapRef: name: keyvalcfgmap dnsPolicy: ClusterFirst restartPolicy: Never status: {}
112. Create an env file file.env with var1=val1 and create a configmap envcfgmap from this env file and verify the configmap
echo var1=val1 > file.env cat file.envkubectl create cm envcfgmap --from-env-file=file.env kubectl get cm envcfgmap -o yaml --export
113. Create an nginx pod and load environment values from the above configmap envcfgmap and exec into the pod and verify the environment variables and delete the pod
// first run this command to save the pod yml kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx-pod.yml// edit the yml to below file and create kubectl create -f nginx-pod.yml// verify kubectl exec -it nginx -- env
kubectl delete po nginx
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx resources: {} env: - name: ENVIRONMENT valueFrom: configMapKeyRef: name: envcfgmap key: var1 dnsPolicy: ClusterFirst restartPolicy: Never status: {}
114. Create a configmap called cfgvolume with values var1=val1, var2=val2 and create an nginx pod with volume nginx-volume which reads data from this configmap cfgvolume and put it on the path /etc/cfg
// first create a configmap cfgvolume kubectl create cm cfgvolume --from-literal=var1=val1 --from-literal=var2=val2// verify the configmap kubectl describe cm cfgvolume// create the config map kubectl create -f nginx-volume.yml// exec into the pod kubectl exec -it nginx -- /bin/sh// check the path cd /etc/cfg ls
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: volumes: - name: nginx-volume configMap: name: cfgvolume containers: - image: nginx name: nginx resources: {} volumeMounts: - name: nginx-volume mountPath: /etc/cfg dnsPolicy: ClusterFirst restartPolicy: Never status: {}
115. Create a pod called secbusybox with the image busybox which executes command sleep 3600 and makes sure any Containers in the Pod, all processes run with user ID 1000 and with group id 2000 and verify.
// create yml file with dry-run kubectl run secbusybox --image=busybox --restart=Never --dry-run -o yaml -- /bin/sh -c "sleep 3600;" > busybox.yml// edit the pod like below and create kubectl create -f busybox.yml// verify kubectl exec -it secbusybox -- sh id // it will show the id and group
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: secbusybox name: secbusybox spec: securityContext: # add security context runAsUser: 1000 runAsGroup: 2000 containers: - args: - /bin/sh - -c - sleep 3600; image: busybox name: secbusybox resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
116. Create the same pod as above this time set the securityContext for the container as well and verify that the securityContext of container overrides the Pod level securityContext.
// create yml file with dry-run kubectl run secbusybox --image=busybox --restart=Never --dry-run -o yaml -- /bin/sh -c "sleep 3600;" > busybox.yml// edit the pod like below and create kubectl create -f busybox.yml// verify kubectl exec -it secbusybox -- sh id // you can see container securityContext overides the Pod level
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: secbusybox name: secbusybox spec: securityContext: runAsUser: 1000 containers: - args: - /bin/sh - -c - sleep 3600; image: busybox securityContext: runAsUser: 2000 name: secbusybox resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
117. Create pod with an nginx image and configure the pod with capabilities NET_ADMIN and SYS_TIME verify the capabilities
// create the yaml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// edit as below and create pod kubectl create -f nginx.yml// exec and verify kubectl exec -it nginx -- sh cd /proc/1 cat status// you should see these values CapPrm: 00000000aa0435fb CapEff: 00000000aa0435fb
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx securityContext: capabilities: add: ["SYS_TIME", "NET_ADMIN"] name: nginx resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
118. Create a Pod nginx and specify a memory request and a memory limit of 100Mi and 200Mi respectively.
// create a yml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// add the resources section and create kubectl create -f nginx.yml// verify kubectl top pod
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx resources: requests: memory: "100Mi" limits: memory: "200Mi" dnsPolicy: ClusterFirst restartPolicy: Never status: {}
119. Create a Pod nginx and specify a CPU request and a CPU limit of 0.5 and 1 respectively.
// create a yml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// add the resources section and create kubectl create -f nginx.yml// verify kubectl top pod
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx resources: requests: cpu: "0.5" limits: cpu: "1" dnsPolicy: ClusterFirst restartPolicy: Never status: {}
120. Create a Pod nginx and specify both CPU, memory requests and limits together and verify.
// create a yml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// add the resources section and create kubectl create -f nginx.yml// verify kubectl top pod
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx resources: requests: memory: "100Mi" cpu: "0.5" limits: memory: "200Mi" cpu: "1" dnsPolicy: ClusterFirst restartPolicy: Never status: {}
121. Create a Pod nginx and specify a memory request and a memory limit of 100Gi and 200Gi respectively which is too big for the nodes and verify pod fails to start because of insufficient memory
// create a yml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// add the resources section and create kubectl create -f nginx.yml// verify kubectl describe po nginx // you can see pending state
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx resources: requests: memory: "100Gi" cpu: "0.5" limits: memory: "200Gi" cpu: "1" dnsPolicy: ClusterFirst restartPolicy: Never status: {}
122. Create a secret mysecret with values user=myuser and password=mypassword
kubectl create secret generic my-secret --from-literal=username=user --from-literal=password=mypassword
123. List the secrets in all namespaces
kubectl get secret --all-namespaces
124. Output the yaml of the secret created above
kubectl get secret my-secret -o yaml
125. Create an nginx pod which reads username as the environment variable
// create a yml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// add env section below and create kubectl create -f nginx.yml//verify kubectl exec -it nginx -- env
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx env: - name: USER_NAME valueFrom: secretKeyRef: name: my-secret key: username resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
126. Create an nginx pod which loads the secret as environment variables
// create a yml file kubectl run nginx --image=nginx --restart=Never --dry-run -o yaml > nginx.yml// add env section below and create kubectl create -f nginx.yml//verify kubectl exec -it nginx -- env
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx envFrom: - secretRef: name: my-secret resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
127. List all the service accounts in the default namespace
kubectl get sa
128. List all the service accounts in all namespaces
kubectl get sa --all-namespaces
129. Create a service account called admin
kubectl create sa admin
130. Output the YAML file for the service account we just created
kubectl get sa admin -o yaml
131. Create a busybox pod which executes this command sleep 3600 with the service account admin and verify
kubectl run busybox --image=busybox --restart=Never --dry-run -o yaml -- /bin/sh -c "sleep 3600" > busybox.ymlkubectl create -f busybox.yml// verify kubectl describe po busybox
apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: busybox name: busybox spec: serviceAccountName: admin containers: - args: - /bin/sh - -c - sleep 3600 image: busybox name: busybox resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
Observability (18%)
Practice questions based on these concepts
- Understand LivenessProbes and ReadinessProbes
- Understand Container Logging
- Understand how to monitor applications in kubernetes
- Understand Debugging in Kubernetes
132. Create an nginx pod with containerPort 80 and it should only receive traffic only it checks the endpoint / on port 80 and verify and delete the pod.
nginx-pod.yamlapiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx ports: - containerPort: 80 readinessProbe: httpGet: path: / port: 80 resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
kubectl run nginx --image=nginx --restart=Never --port=80 --dry-run -o yaml > nginx-pod.yaml// add the readinessProbe section and create kubectl create -f nginx-pod.yaml// verify kubectl describe pod nginx | grep -i readiness
kubectl delete po nginx
133. Create an nginx pod with containerPort 80 and it should check the pod running at endpoint / healthz on port 80 and verify and delete the pod.
nginx-pod.yamlapiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx ports: - containerPort: 80 livenessProbe: httpGet: path: /healthz port: 80 resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
kubectl run nginx --image=nginx --restart=Never --port=80 --dry-run -o yaml > nginx-pod.yaml// add the livenessProbe section and create kubectl create -f nginx-pod.yaml// verify kubectl describe pod nginx | grep -i readiness
kubectl delete po nginx
134. Create an nginx pod with containerPort 80 and it should check the pod running at endpoint /healthz on port 80 and it should only receive traffic only it checks the endpoint / on port 80. verify the pod.
nginx-pod.yamlapiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx ports: - containerPort: 80 livenessProbe: httpGet: path: /healthz port: 80 readinessProbe: httpGet: path: / port: 80 resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
kubectl run nginx --image=nginx --restart=Never --port=80 --dry-run -o yaml > nginx-pod.yaml// add the livenessProbe and readiness section and create kubectl create -f nginx-pod.yaml// verify kubectl describe pod nginx | grep -i readiness kubectl describe pod nginx | grep -i liveness
135. Check what all are the options that we can configure with readiness and liveness probes
kubectl explain Pod.spec.containers.livenessProbe
kubectl explain Pod.spec.containers.readinessProbe
136. Create the pod nginx with the above liveness and readiness probes so that it should wait for 20 seconds before it checks liveness and readiness probes and it should check every 25 seconds.
nginx-pod.yamlapiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: nginx name: nginx spec: containers: - image: nginx name: nginx ports: - containerPort: 80 livenessProbe: initialDelaySeconds: 20 periodSeconds: 25 httpGet: path: /healthz port: 80 readinessProbe: initialDelaySeconds: 20 periodSeconds: 25 httpGet: path: / port: 80 resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
kubectl create -f nginx-pod.yaml
137. Create a busybox pod with this command “echo I am from busybox pod; sleep 3600;” and verify the logs.
kubectl run busybox --image=busybox --restart=Never -- /bin/sh -c "echo I am from busybox pod; sleep 3600;"
kubectl logs busybox
138. copy the logs of the above pod to the busybox-logs.txt and verify
kubectl logs busybox > busybox-logs.txt
cat busybox-logs.txt
139. List all the events sorted by timestamp and put them into file.log and verify
kubectl get events --sort-by=.metadata.creationTimestamp// putting them into file.log kubectl get events --sort-by=.metadata.creationTimestamp > file.logcat file.log
140. Create a pod with an image alpine which executes this command ”while true; do echo ‘Hi I am from alpine’; sleep 5; done” and verify and follow the logs of the pod.
// create the pod kubectl run hello --image=alpine --restart=Never -- /bin/sh -c "while true; do echo 'Hi I am from Alpine'; sleep 5;done"// verify and follow the logs kubectl logs --follow hello
141. Create the pod with this kubectl create -f https://gist.githubusercontent.com/bbachi/212168375b39e36e2e2984c097167b00/raw/1fd63509c3ae3a3d3da844640fb4cca744543c1c/not-running.yml. The pod is not in the running state. Debug it.
// create the pod kubectl create -f https://gist.githubusercontent.com/bbachi/212168375b39e36e2e2984c097167b00/raw/1fd63509c3ae3a3d3da844640fb4cca744543c1c/not-running.yml// get the pod kubectl get pod not-running kubectl describe po not-running// it clearly says ImagePullBackOff something wrong with image kubectl edit pod not-running // it will open vim editor or kubectl set image pod/not-running not-running=nginx
142. This following yaml creates 4 namespaces and 4 pods. One of the pod in one of the namespaces are not in the running state. Debug and fix it. https://gist.githubusercontent.com/bbachi/1f001f10337234d46806929d12245397/raw/84b7295fb077f15de979fec5b3f7a13fc69c6d83/problem-pod.yaml.
kubectl create -f https://gist.githubusercontent.com/bbachi/1f001f10337234d46806929d12245397/raw/84b7295fb077f15de979fec5b3f7a13fc69c6d83/problem-pod.yaml// get all the pods in all namespaces kubectl get po --all-namespaces// find out which pod is not running kubectl get po -n namespace2// update the image kubectl set image pod/pod2 pod2=nginx -n namespace2// verify again kubectl get po -n namespace2
143. Get the memory and CPU usage of all the pods and find out top 3 pods which have the highest usage and put them into the cpu-usage.txt file
// get the top 3 hungry pods kubectl top pod --all-namespaces | sort --reverse --key 3 --numeric | head -3// putting into file kubectl top pod --all-namespaces | sort --reverse --key 3 --numeric | head -3 > cpu-usage.txt// verify cat cpu-usage.txt
Services and Networking (13%)
Practice questions based on these concepts
- Understand Services
- Demonstrate a basic understanding of NetworkPolicies
144. Create an nginx pod with a yaml file with label my-nginx and expose the port 80
nginx.yaml:apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: app: my-nginx name: nginx spec: containers: - image: nginx name: nginx ports: - containerPort: 80 resources: {} dnsPolicy: ClusterFirst restartPolicy: Never status: {}
kubectl run nginx --image=nginx --restart=Never --port=80 --dry-run -o yaml > nginx.yaml// edit the label app: my-nginx and create the pod kubectl create -f nginx.yaml
145. Create the service for this nginx pod with the pod selector app: my-nginx
nginx-svc.yaml:
apiVersion: v1 kind: Service metadata: name: my-service spec: selector: app: my-nginx ports: - protocol: TCP port: 80 targetPort: 9376
// create the below service kubectl create -f nginx-svc.yaml
146. Find out the label of the pod and verify the service has the same label
// get the pod with labels kubectl get po nginx --show-labels// get the service and chekc the selector column kubectl get svc my-service -o wide
147. Delete the service and create the service with kubectl expose command and verify the label
// delete the service kubectl delete svc my-service// create the service again kubectl expose po nginx --port=80 --target-port=9376// verify the label kubectl get svc -l app=my-nginx
148. Delete the service and create the service again with type NodePort
// delete the service kubectl delete svc nginx// create service with expose command kubectl expose po nginx --port=80 --type=NodePort
149. Create the temporary busybox pod and hit the service. Verify the service that it should return the nginx page index.html.
// get the clusterIP from this command kubectl get svc nginx -o wide// create temporary busybox to check the nodeport kubectl run busybox --image=busybox --restart=Never -it --rm -- wget -o- <Cluster IP>:80
150. Create a NetworkPolicy which denies all ingress traffic
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: default-deny spec: podSelector: {} policyTypes: - Ingress
Conclusion
CKAD is a performance-based exam and it’s all about completing 19 questions within 2 hours. We need a lot of practice for it. These 150 questions give you enough practice for the exam. The more you practice the more comfortable you feel during the exam. Practice. Practice. Practice.