Pass the Linux Foundation Kubernetes Application Developer CKAD Questions and answers with CertsForce

Solution:

To have Kubernetes automatically restart a pod when an endpoint returns an HTTP 500 on the /healthz endpoint, you will need to configure liveness and readiness probes on the pod.

First, you will need to create a livenessProbe and a readinessProbe in the pod's definition yaml file. The livenessProbe will check the /healthz endpoint, and if it returns an HTTP 500, the pod will be restarted. The readinessProbe will check the /started endpoint, and if it returns an HTTP 500, the pod will not receive traffic.

Here's an example of how you can configure the liveness and readiness probes in the pod definition yaml file:

apiVersion: v1

kind: Pod

metadata:

name: probe-pod

spec:

containers:

- name: probe-pod

image:

ports:

- containerPort: 8080

livenessProbe:

httpGet:

path: /healthz

port: 8080

initialDelaySeconds: 15

periodSeconds: 10

failureThreshold: 3

readinessProbe:

httpGet:

path: /started

port: 8080

initialDelaySeconds: 15

periodSeconds: 10

failureThreshold: 3

The httpGet specifies the endpoint to check and the port to use. The initialDelaySeconds is the amount of time the pod will wait before starting the probe. periodSeconds is the amount of time between each probe check, and the failureThreshold is the number of failed probes before the pod is considered unresponsive.

You can use kubectl to create the pod by running the following command:

kubectl apply -f .yaml

Once the pod is created, Kubernetes will start monitoring it using the configured liveness and readiness probes. If the /healthz endpoint returns an HTTP 500, the pod will be restarted. If the /started endpoint returns an HTTP 500, the pod will not receive traffic.

Please note that if the failure threshold is set to 3, it means that if the probe fails 3 times consecutively it will be considered as a failure.

The above configuration assumes that the application is running on port 8080 and the endpoints are available on the same port.

Solution:

Solution:

Solution:

Solution:

To allow a pod to send and receive traffic only to and from specific pods, you can use network policies in Kubernetes.

First, you will need to create a network policy that defines the allowed traffic. You can create a network policy yaml file with the following rules:

apiVersion: networking.k8s.io/v1

kind: NetworkPolicy

metadata:

name: newpod-network-policy

namespace: default

spec:

podSelector:

matchLabels:

app: kdsn00201-newpod

ingress:

- from:

- podSelector:

matchLabels:

app: web

- podSelector:

matchLabels:

app: storage

This policy will only allow incoming traffic to the pod with the label app=kdsn00201-newpod from pods with the label app=web or app=storage. If you have different labels on your web and storage pods please update the matchLabels accordingly.

Once you have created the network policy, you can apply it to the cluster by running the following command:

kubectl apply -f .yaml

This will apply the network policy to the cluster, and the newpod will only be able to send and receive traffic to and from the web and storage pods.

Please note that, NetworkPolicy resource is not available by default, you need to enable the NetworkPolicy feature on your Kubernetes cluster. This feature is enabled by default on some clusters and must be explicitly enabled on others. You can check if NetworkPolicy is available by running the command kubectl api-versions | grep networking

Also, you need to ensure that the pods that you want to allow traffic to and from are running on the same namespace.

ssh ckad00043

You have two deliverables here:

Figure out what RBAC permissions the scraper Deployment needs (the logs will usually show “Forbidden” with the missing verb/resource).

Create a ServiceAccount named scraper in namespace cute-panda (and in practice, you then bind the needed permissions to it and use it in the Deployment so it actually works).

Below is the exact CKAD-style workflow.

1) Find the missing RBAC permissions (use logs + events)

1.1 Identify the pods for the Deployment

kubectl -n cute-panda get deploy scraper

kubectl -n cute-panda get pods -l app=scraper 2>/dev/null || kubectl -n cute-panda get pods

Pick one pod name and check logs:

kubectl -n cute-panda logs deploy/scraper --tail=100

If the pod is crashlooping and logs are short:

POD=$(kubectl -n cute-panda get pods -o jsonpath='{.items[0].metadata.name}')

kubectl -n cute-panda logs "$POD" --previous --tail=200

1.2 Look specifically for “Forbidden” lines

Most apps print errors like:

... is forbidden: User "system:serviceaccount:cute-panda:default" cannot list resource "pods" in API group "" in the namespace "cute-panda"

or cannot get resource "configmaps"...

or cannot watch ...

If you don’t see it in logs, check events:

kubectl -n cute-panda get events --sort-by=.lastTimestamp | tail -n 30

1.3 Extract verb/resource/apiGroup from the error

From a typical Kubernetes RBAC “forbidden” message, capture:

verb: get/list/watch/create/update/patch/delete

resource: pods, configmaps, secrets, deployments, etc.

apiGroup: "" (core), apps, batch, etc.

namespace: cute-panda (this is a namespaced permission if it’s a Role)

You may have multiple “cannot …” lines → you need to allow all of them.

2) Create the ServiceAccount scraper (required by the task)

kubectl -n cute-panda create serviceaccount scraper

kubectl -n cute-panda get sa scraper

3) Create the RBAC objects to grant the needed permissions

The task says “A Deployment needs specific RBAC permissions” — in CKAD, that usually means: Role + RoleBinding (namespaced) bound to your new ServiceAccount.

3.1 Create a Role (template you fill from the log output)

Create scraper-role.yaml:

cat <<'EOF' > scraper-role.yaml

apiVersion: rbac.authorization.k8s.io/v1

kind: Role

metadata:

name: scraper-role

namespace: cute-panda

rules:

# EXAMPLE ONLY: replace these rules with what your logs show

- apiGroups: [""]

resources: ["pods"]

verbs: ["get","list","watch"]

EOF

Apply it:

kubectl apply -f scraper-role.yaml

3.2 Bind the Role to the ServiceAccount

kubectl -n cute-panda create rolebinding scraper-rb \

--role=scraper-role \

--serviceaccount=cute-panda:scraper

Verify:

kubectl -n cute-panda get role scraper-role

kubectl -n cute-panda get rolebinding scraper-rb -o yaml

4) Update the Deployment to use the new ServiceAccount (so it actually works)

Check current SA (likely default):

kubectl -n cute-panda get deploy scraper -o jsonpath='{.spec.template.spec.serviceAccountName}{"\n"}'

Patch it to use scraper:

kubectl -n cute-panda patch deploy scraper -p '{"spec":{"template":{"spec":{"serviceAccountName":"scraper"}}}}'

Rollout:

kubectl -n cute-panda rollout status deploy scraper

Re-check logs to confirm RBAC errors are gone:

kubectl -n cute-panda logs deploy/scraper --tail=100

Solution:

Solution:

Below is an exam-style, step-by-step solution (commands + verification). Follow exactly on host ckad000.

0) Connect to the right host

ssh ckad000

(Optional but good sanity check)

kubectl config current-context

kubectl get ns

1) Inspect the existing Deployment (to know its labels/ports)

kubectl -n prod get deploy nginx-deployment

kubectl -n prod get deploy nginx-deployment -o wide

Check what labels the Pod template already has (important for the Service selector):

kubectl -n prod get deploy nginx-deployment -o jsonpath='{.spec.template.metadata.labels}{"\n"}'

Check container ports (so we expose the correct targetPort):

kubectl -n prod get deploy nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].ports}{"\n"}'

If ports output is empty, it’s still often nginx on 80, but the safest is to confirm by describing a pod later.

2) Update Deployment to 2 replicas

Fastest:

kubectl -n prod scale deploy nginx-deployment --replicas=2

Verify:

kubectl -n prod get deploy nginx-deployment

3) Add label role=webFrontEnd to the Pod (Pod template label)

You must add it under:

spec.template.metadata.labels

Use a patch (quick + safe):

kubectl -n prod patch deploy nginx-deployment \

-p '{"spec":{"template":{"metadata":{"labels":{"role":"webFrontEnd"}}}}}'

Verify the Deployment template now includes it:

kubectl -n prod get deploy nginx-deployment -o jsonpath='{.spec.template.metadata.labels}{"\n"}'

Now verify the running Pods have the label (important!):

kubectl -n prod get pods --show-labels

If the label doesn’t show on pods immediately, wait for rollout:

kubectl -n prod rollout status deploy nginx-deployment

kubectl -n prod get pods --show-labels

4) Create a NodePort Service rover exposing the Deployment’s Pods

4.1 Get a reliable target port

Try to read containerPort:

kubectl -n prod get deploy nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].ports[0].containerPort}{"\n"}'

If this prints a number (commonly 80), use it as --target-port.

If it prints nothing/empty, check a pod:

POD=$(kubectl -n prod get pod -l role=webFrontEnd -o jsonpath='{.items[0].metadata.name}')

kubectl -n prod describe pod "$POD" | sed -n '/Containers:/,/Conditions:/p' | sed -n '/Ports:/,/Environment:/p'

Assuming nginx is on 80 (most common), create the service:

kubectl -n prod expose deploy nginx-deployment \

--name=rover \

--type=NodePort \

--port=80 \

--target-port=80

If your nginx container port is different (e.g., 8080), change --target-port=8080 accordingly.

5) Verify Service + endpoints (critical)

kubectl -n prod get svc rover -o wide

kubectl -n prod describe svc rover

kubectl -n prod get endpoints rover -o wide

You should see 2 endpoints (matching 2 pods).

Also confirm the pods are Ready:

kubectl -n prod get pods -l role=webFrontEnd -o wide

Quick “CKAD checkpoints”

Deployment in prod has replicas=2

Pod template has label role=webFrontEnd

Service rover in prod is NodePort

Service endpoints point to the nginx pods