Linux Foundation Kubernetes Administrator CKA Questions & Answers

• Question 21:

  SIMULATION

  Configure the kubelet systemd- managed service, on the node labelled with name=wk8s-node-1, to launch a pod containing a single container of Image httpd named webtool automatically. Any spec files required should be placed in the /etc/

  kubernetes/manifests directory on the node.

  You can ssh to the appropriate node using:

  [student@node-1] $ ssh wk8s-node-1

  You can assume elevated privileges on the node with the following command:

  [student@wk8s-node-1] $ | sudo -i

  Correct Answer: Check the answer in explanation.

  Solution

  

  

  

• Question 22:

  SIMULATION For this item, you will have to ssh to the nodes ik8s-master-0 and ik8s-node-0 and complete all tasks on these nodes. Ensure that you return to the base node (hostname: node-1) when you have completed this item. Context

  As an administrator of a small development team, you have been asked to set up a Kubernetes cluster to test the viability of a new application.

  Task

  You must use kubeadm to perform this task. Any kubeadm invocations will require the use of the -- ignore-preflight-errors=all option.

  Configure the node ik8s-master-O as a master node. .

  Join the node ik8s-node-o to the cluster.

  Correct Answer: Check the answer in explanation.

  Solution

  You must use the kubeadm configuration file located at /etc/kubeadm.conf when initializing your cluster.

  You may use any CNI plugin to complete this task, but if you don't have your favourite CNI plugin's manifest URL at hand, Calico is one popular option:

  https://docs.projectcalico.org/v3.14/manifests/calico.yaml Docker is already installed on both nodes and apt has been configured so that you can install the required tools.

• Question 23:

  SIMULATION

  Given a partially-functioning Kubernetes cluster, identify symptoms of failure on the cluster.

  Determine the node, the failing service, and take actions to bring up the failed service and restore the health of the cluster. Ensure that any changes are made permanently.

  You can ssh to the relevant I nodes (bk8s-master-0 or bk8s-node-0) using:

  [student@node-1] $ ssh

  You can assume elevated privileges on any node in the cluster with the following command:

  [student@nodename] $ | sudo -i

  Correct Answer: Check the answer in explanation.

  solution

  

  

• Question 24:

  SIMULATION

  Create a persistent volume with name app-data, of capacity 2Gi and access mode ReadWriteMany. The type of volume is hostPath and its location is /srv/app-data.

  Correct Answer: Check the answer in explanation.

  Persistent Volume A persistent volume is a piece of storage in a Kubernetes cluster. PersistentVolumes are a cluster- level resource like nodes, which don't belong to any namespace. It is provisioned by the administrator and has a particular file size. This way, a developer deploying their app on Kubernetes need not know the underlying infrastructure. When the developer needs a certain amount of persistent storage for their application, the system administrator configures the cluster so that they consume the PersistentVolume provisioned in an easy way. Creating Persistent Volume kind: PersistentVolume apiVersion: v1 metadata: name:app-data spec: capacity: # defines the capacity of PV we are creating storage: 2Gi #the amount of storage we are tying to claim accessModes: # defines the rights of the volume we are creating

  -ReadWriteMany

  hostPath:

  path: "/srv/app-data" # path to which we are creating the volume Challenge

  Create a Persistent Volume named app-data, with access mode ReadWriteMany, storage classname shared, 2Gi of storage capacity and the host path /srv/app-data.

  

  2.

  Save the file and create the persistent volume.

  3.

  View the persistent volume.

  

  

  Our persistent volume status is available meaning it is available and it has not been mounted yet. This status will change when we mount the persistentVolume to a persistentVolumeClaim. PersistentVolumeClaim In a real ecosystem, a system admin will create the PersistentVolume then a developer will create a PersistentVolumeClaim which will be referenced in a pod. A PersistentVolumeClaim is created by specifying the minimum size and the access mode they require from the persistentVolume. Challenge Create a Persistent Volume Claim that requests the Persistent Volume we had created above. The claim should request 2Gi. Ensure that the Persistent Volume Claim has the same storageClassName as the persistentVolume you had previously created. kind: PersistentVolume apiVersion: v1 metadata: name:app-data spec: accessModes:

  -ReadWriteMany resources: requests: storage: 2Gi storageClassName: shared

  2.

  Save and create the pvc njerry191@cloudshell:~ (extreme-clone-2654111)$ kubect1 create -f app-data.yaml persistentvolumeclaim/app-data created

  3.

  View the pvc

  4.

  Let's see what has changed in the pv we had initially created.

  

  

  Our status has now changed from available to bound.

  5. Create a new pod named myapp with image nginx that will be used to Mount the Persistent Volume Claim with the path /var/app/config. Mounting a Claim apiVersion: v1 kind: Pod metadata: creationTimestamp: null name: app-data spec: volumes:

  -name:congigpvc persistenVolumeClaim: claimName: app-data containers:

  -image: nginx name: app volumeMounts:

  -mountPath: "/srv/app-data " name: configpvc

• Question 25:

  Create a namespace called 'development' and a pod with image nginx called nginx on this namespace.

  Correct Answer: Check the answer in explanation.

  kubectl create namespace development kubectl run nginx --image=nginx --restart=Never -n development

• Question 26:

  Create a nginx pod with label env=test in engineering namespace .

  Correct Answer: Check the answer in explanation.

  kubectl run nginx --image=nginx --restart=Never --labels=env=test --namespace=engineering --dry- run -o yaml > nginx-pod.yaml kubectl run nginx --image=nginx --restart=Never --labels=env=test --namespace=engineering --dry- run -o yaml | kubectl create -n engineering -f YAML File:

  apiVersion: v1 kind: Pod metadata: name: nginx namespace: engineering labels: env: test spec: containers:

  -name: nginx image: nginx imagePullPolicy: IfNotPresent restartPolicy: Never

  kubectl create -f nginx-pod.yaml

• Question 27:

  Get list of all pods in all namespaces and write it to file "/opt/pods-list.yaml"

  Correct Answer: Check the answer in explanation.

  kubectl get po -all-namespaces > /opt/pods-list.yaml

• Question 28:

  Create a pod with image nginx called nginx and allow traffic on port 80

  Correct Answer: Check the answer in explanation.

  kubectl run nginx --image=nginx --restart=Never --port=80

• Question 29:

  Create a busybox pod that runs the command "env" and save the output to "envpod" file

  Correct Answer: Check the answer in explanation.

  Solution

  kubectl run busybox --image=busybox --restart=Never -rm -it -- env>; envpod.yaml

• Question 30:

  List pod logs named "frontend" and search for the pattern "started" and write it to a file "/opt/error- logs"

  Correct Answer: Check the answer in explanation.

  Kubectl logs frontend | grep -i "started" > /opt/error-logs