ckad_questions_answers

==========================k8s questions ============================
https://medium.com/bb-tutorials-and-thoughts/practice-enough-with-these-questions-for-the-ckad-exam-2f42d1228552

=================================================================
				BASIC CORE CONCEPT Questions
=================================================================
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 nginxkubectl 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-alpinekubectl describe po nginx// another way it will open vi editor and change the version
kubeclt edit po nginxkubectl 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}{"\n"}'



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 -- lskubectl 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
====================================================================

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: {}



multi-container pod

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.yamlkubectl 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: {}

multi-container.yaml

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
============================================================

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=nginxkubectl 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=20kubectl 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 webappkubectl 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:1.17.4kubectl describe deploy webapp | grep Image

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

kubectl rollout history deploy webappkubectl 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 webappkubectl 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:1.16.1kubectl describe deploy webapp | grep Imagekubectl 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=3kubectl 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:1.100kubectl 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:latestkubectl 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 webappkubectl 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=85kubectl get hpakubectl get pod -l app=webapp

81. Clean the cluster by deleting deployment and hpa you just created

kubectl delete deploy webappkubectl 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.yamlkubectl 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
==========================================================

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.yamlkubectl 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.yamlkubectl 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 podkubectl create -f 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.yamlkubectl 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
============================================================

    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 datakubectl 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.txtkubectl 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 -- envkubectl 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 -- envkubectl 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
==================================================================

    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.

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 readinesskubectl delete po nginx

apiVersion: 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: {}


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.

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 readinesskubectl delete po nginx

apiVersion: 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: {}

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.

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

apiVersion: 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: {}


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.

kubectl create -f nginx-pod.yaml

apiVersion: 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: {}


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.txtcat 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
==============================================================
    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

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


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: {}


145. Create the service for this nginx pod with the pod selector app: my-nginx

// create the below service
kubectl create -f nginx-svc.yaml


apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9376
	  
	  
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
  
  
  
  
  
  ================================Container Design Patterns============================
  https://www.usenix.org/system/files/conference/hotcloud16/hotcloud16_burns.pdf
  
  https://medium.com/@karthi.net/8-container-design-patterns-that-you-should-know-970a1d6a594c