Linux Foundation CKA Exam Dumps

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solution

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

solution

Task Summary

You are managing a WordPress Deployment in namespace relative-fawn.

Deployment has 3 replicas.

Pods are not starting due to high resource requests.

Your job: Adjust CPU and memory requests so that all 3 pods evenly split the node's capacity.

Step-by-Step Solution

1 SSH into the correct host

bash

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ssh cka000058

Skipping this will result in a zero score.

2 Check node resource capacity

You need to know the node's CPU and memory resources.

bash

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kubectl describe node | grep -A5 'Capacity'

Example output:

yaml

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Capacity:

cpu: 3

memory: 3Gi

Let's assume the node has:

3 CPUs

3Gi memory

So for 3 pods, divide evenly:

CPU request per pod: 1

Memory request per pod: 1Gi

In the actual exam, check real values and divide accordingly. If the node has 4 CPUs and 8Gi, you'd allocate ~1.33 CPUs and ~2.66Gi RAM per pod (rounded reasonably).

3 Edit the Deployment

Edit the WordPress deployment in the relative-fawn namespace:

kubectl edit deployment wordpress -n relative-fawn

Look for the resources section under spec.template.spec.containers like this:

resources:

requests:

cpu: '1'

memory: '1Gi'

If the section doesn't exist, add it manually.

Save and exit the editor (:wq if using vi).

4 Confirm changes

Wait a few seconds, then check:

kubectl get pods -n relative-fawn

Ensure all 3 pods are in Running state.

You can also describe a pod to confirm resource requests are set:

kubectl describe pod -n relative-fawn | grep -A5 'Containers'

ssh cka000058

kubectl describe node | grep -A5 'Capacity'

kubectl edit deployment wordpress -n relative-fawn

# Set CPU: 1, Memory: 1Gi (or according to node capacity)

kubectl get pods -n relative-fawn

Task Summary

You need to:

SSH into the correct node: cka000055

Use kubectl to list all cert-manager CRDs, and save that list to ~/resources.yaml

Do not use any output format flags like -o yaml

Extract the documentation for the spec.subject field of the Certificate custom resource and save it to ~/subject.yaml

Step-by-Step Instructions

Step 1: SSH into the node

ssh cka000055

Step 2: List cert-manager CRDs and save to a file

First, identify all cert-manager CRDs:

kubectl get crds | grep cert-manager

Then extract them without specifying an output format:

kubectl get crds | grep cert-manager | awk '{print $1}' | xargs kubectl get crd > ~/resources.yaml

This saves the default kubectl get output to the required file without formatting flags.

Step 3: Get documentation for spec.subject in the Certificate CRD

Run the following command:

kubectl explain certificate.spec.subject > ~/subject.yaml

This extracts the field documentation and saves it to the specified file.

If you're not sure of the resource, verify it exists:

kubectl get crd certificates.cert-manager.io

Final Command Summary

ssh cka000055

kubectl get crds | grep cert-manager | awk '{print $1}' | xargs kubectl get crd > ~/resources.yaml

kubectl explain certificate.spec.subject > ~/subject.yaml