CKAD Exercises - Part 1

5-minute read
kubernetes • ckad • certification
Table of Contents

Core Concepts

Namespaces

Exercise 1

List all namespaces.

Show Solution

kubectl get namespaces

Exercise 2

Create a new namespace mynamespace.

Show Solution

kubectl create namespace mynamespace

Exercise 3

List all pods in a namespace.

Show Solution

kubectl get pods --namespace mynamespace

Exercise 4

List all pods in all namespaces.

Show Solution

kubectl get pods --all-namespaces

Exercise 5

List all deployments and services in all namespaces.

Show Solution

kubectl get deployments --all-namespaces
kubectl get services --all-namespaces

Pod Basics

Exercise 6

Create a new pod nginx-webapp in a namespace of your choice other than default. Confirm that the pod has started successfully.

Show Solution

kubectl run nginx-webapp --image=nginx --restart=Never --namespace mynamespace
kubectl get pod nginx-webapp --namespace mynamespace
## Make sure the pod is in STATUS = Running
## Example:
## NAME        READY   STATUS    RESTARTS   AGE
## nginx-web   1/1     Running   0          2m6s

NOTE: Note that we added --restart=Never to make sure that only a pod is created. If we would omit this, a deployment would be created that would spin up our pod. See here for more information.

Exercise 7

Create a pod nginx with image nginx:1.18-alpine using a YAML file.

Show Solution

kubectl run nginx --image=nginx:1.18-alpine --restart=Never -o yaml --dry-run=client > pod.yaml
kubectl create -f pod.yaml

Exercise 8

Get the pod specification for an existing pod in YAML format.

Show Solution

kubectl get pod nginx -o yaml

Exercise 9

Get the pod specification for an existing pod in JSON format.

Show Solution

kubectl get pod nginx -o json

Exercise 10

Get the details for an existing pod (such as pod status, recent events, related resources, etc.).

Show Solution

kubectl describe pod nginx

Exercise 11

Delete a pod.

Show Solution

kubectl delete pod nginx

Exercise 12

Create a pod busybox that executes the shell command sleep 3600 and then stops.

Show Solution

kubectl run busybox --image=busybox --restart=Never -- sh -c "sleep 3600"

Exercise 13

Create a pod with image busybox that only prints ‘Hi!’ and then stops. Open the pod logs and check if there is any output.

Show Solution

kubectl run my-busybox-pod --image=busybox --restart=Never -- sh -c "echo Hi!" 
kubectl logs my-busybox-pod

Exercise 14

Connect to a pod and print all environment variables.

Show Solution

kubectl exec nginx -- sh -c env
## or connect to it in interactive mode
kubectl exec nginx -it sh
## print all environment variables using the 'env' command

Exercise 15

Create a pod nginx with image nginx:1.18-alpine. When the pod was created, change its image to nginx:1.19-alpine. Convince yourself that the pod has been successfully updated.

Show Solution

kubectl run nginx --image=nginx:1.18-alpine --restart=Never 
kubectl set image pod/nginx nginx=nginx:1.19-alpine
kubectl describe pod nginx
## 1: Inspect the output and make sure that the Image attribute has been updated to 
## nginx:1.19-alpine (see attribute "Containers" > "nginx" > "Image")
## 2: The event log should contain information about a successful image pull and pod restart.

Exercise 16

Show the logs of a previously crashed pod.

Show Solution

kubectl logs my-busybox-pod -p

TIP: This command does not show logs for already terminated pods!

Exercise 17

Show a pods logs from the last hour.

Show Solution

kubectl logs --since=1h nginx

Exercise 18

  1. Create a pod nginx-server with image nginx and expose it on port 80.
  2. Create another pod nginx-checker with image busybox that fetches the index HTML page from nginx-server and prints it to standard output.
  3. Check the logs of nginx-checker to see the HTML content.
Show Solution

kubectl run nginx-server --image=nginx --restart=Never --port 80
kubectl describe pod nginx-server
## Read the IP of the nginx-server pod from the `describe` command output above.
kubectl run nginx-checker --image=busybox --restart=Never -- sh -c "wget -O- <IP>"
kubectl logs nginx-checker

Multi-Container Pods

Multi-Container Pod Basics

Exercise 19

Create a multi-container pod named multibox with two busybox containers that execute the command sleep 3600. Check that both containers are running.

Show Solution

# Create a single-container pod as usual and pipe the YAML output into a file
kubectl run multibox --image=busybox --restart=Never --dry-run=client -o yaml -- sh -c "sleep 3600" > multi-container.yaml

Add a second container to the pod specification file we just created.

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: multibox
  name: multibox
spec:
  containers:
  - image: busybox
    name: busybox1
    args:
    - sh
    - -c
    - sleep 3600
  - image: busybox
    name: busybox2
    args:
    - sh
    - -c
    - sleep 3600
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

Create the pod:

kubectl create -f multi-container.yaml
kubectl get pod multibox
# The READY column in the command output should show 2/2 containers in STATUS = Running.

Exercise 20

Check the logs of one of the containers from a multi-container pod.

Show Solution

# Show the logs of container "multibox" of the multi-container pod named "multibox".
kubectl logs multibox -c multibox1

Exercise 21

Show the metrics for all pods.

Show Solution

kubectl top pods

Exercise 22

Show the metrics for all nodes.

Show Solution

kubectl top nodes

Exercise 23

  1. Create a pod that shares a volume with two containers nginx and busybox.
  2. Mount a volume to path /usr/share/nginx/html/ in both containers.
  3. Let the busybox container write the current time into file /usr/share/nginx/html/index.html every 5 seconds.
  4. Start the pod, connect to the nginx container and verify that the time is being updated every 5 seconds.

TIP: Use kubectl exec to connecto to a pod container.

TIP: To write the current time into the file, use the shell command sh -c "while true; do $(date) > /usr/share/nginx/html/index.html; sleep 5; done

Show Solution

kubectl run multi-container --image=nginx --restart=Never --dry-run=client -o yaml > multi-container.yaml

Add the second container to the multi-container.yaml file we just created:

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: multi-container
  name: multi-container
spec:
  volumes:
  - name: html-volume
    emptyDir: {}
  containers:
  - image: nginx
    name: nginx
    resources: {}
    volumeMounts:
    - mountPath: /usr/share/nginx/html/
      name: html-volume
  - image: busybox
    name: busybox
    resources: {}
    volumeMounts:
    - mountPath: /usr/share/nginx/html/
      name: html-volume
    args:
      - sh
      - -c
      - 'while true; do echo "$(date)" > /usr/share/nginx/html/index.html; sleep 5; done'
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

# Verify that the pod started successfully.
kubectl describe pod multi-container 
# Exec into the "nginx" container of the "multi-container" pod .
kubectl exec multi-container -c nginx -it -- sh

Once you’re connected to the container, execute the following command to show the file content:

cat /usr/share/nginx/html/index.html