Linux Foundation CKA - Certified Kubernetes Administrator (CKA) Program

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

Task Summary

Connect to host cka000056

Review existing frontend and backend Deployments

Choose one correct NetworkPolicy from the ~/netpol directory

The policy must:

Allow traffic only from the frontend Deployment to the backend Deployment

Avoid being overly permissive

Apply the correct NetworkPolicy without modifying any sample files

Step-by-Step Instructions

Step 1: SSH into the correct node

ssh cka000056

Step 2: Inspect the frontend Deployment

Check the labels used in the frontend Deployment:

kubectl get deployment -n frontend -o yaml

Look under metadata.labels or spec.template.metadata.labels. Note the app or similar label (e.g., app: frontend).

Step 3: Inspect the backend Deployment

kubectl get deployment -n backend -o yaml

Again, find the labels assigned to the pods (e.g., app: backend).

Step 4: List and review the provided NetworkPolicies

List the available files:

ls ~/netpol

Check the contents of each policy file:

cat ~/netpol/.yaml

Look for a policy that:

Has kind: NetworkPolicy

Applies to the backend namespace

Uses a podSelector that matches the backend pods

Includes an ingress.from rule that references the frontend namespace using a namespaceSelector (and optionally a podSelector)

Does not allow traffic from all namespaces or all pods

Here’s what to look for in a good match:

apiVersion: networking.k8s.io/v1

kind: NetworkPolicy

metadata:

name: allow-frontend-to-backend

namespace: backend

spec:

podSelector:

matchLabels:

app: backend

ingress:

- from:

- namespaceSelector:

matchLabels:

name: frontend

Even better if the policy includes:

- namespaceSelector:

matchLabels:

name: frontend

podSelector:

matchLabels:

app: frontend

This limits access to pods in the frontend namespace with a specific label.

Step 5: Apply the correct NetworkPolicy

Once you’ve identified the best match, apply it:

kubectl apply -f ~/netpol/.yaml

Apply only one file. Do not alter or delete any existing sample.

ssh cka000056

kubectl get deployment -n frontend -o yaml

kubectl get deployment -n backend -o yaml

ls ~/netpol

cat ~/netpol/*.yaml # Review carefully

kubectl apply -f ~/netpol/.yaml

Command Summary

ssh cka000056

kubectl get deployment -n frontend -o yaml

kubectl get deployment -n backend -o yaml

ls ~/netpol

cat ~/netpol/*.yaml # Review carefully

kubectl apply -f ~/netpol/.yaml

kubect1 get pods--sort-by=.metadata.creationTimestamp

image=nginx, image=redis, image=consul

Name nginx container as “nginx-container”

Name redis container as “redis-container”

Name consul container as “consul-container”

Create a pod manifest file for a container and append container

section for rest of the images

kubectl run multi-container --generator=run-pod/v1 --image=nginx --

dry-run -o yaml > multi-container.yaml

# then

vim multi-container.yaml

apiVersion: v1

kind: Pod

metadata:

labels:

run: multi-container

name: multi-container

spec:

containers:

- image: nginx

name: nginx-container

- image: redis

name: redis-container

- image: consul

name: consul-container

restartPolicy: Always