These questions were collected and used to prepare for CKA exam.
- Upgrade the current version of kubernetes from 1.20 to 1.21.0 exactly using the kubeadm utility. Make sure that the upgrade is carried out one node at a time starting with the master node. To minimize downtime, the deployment nginx-deploy should be rescheduled on an alternate node before upgrading each node. Upgrade master node first and drain node worker01 before upgrading it. Pods for nginx-deploy should run on the master node subsequently.
show
On the master node:
root@master:~# kubectl drain master --ignore-daemonsets
root@master:~# apt update
root@master:~# apt-get install -y kubeadm=1.21.0-00
root@master:~# kubeadm upgrade plan v1.21.0
root@master:~# kubeadm upgrade apply v1.21.0
root@master:~# apt-get install -y kubelet=1.21.0-00
root@master:~# kubectl uncordon master
root@master:~# kubectl drain worker01 --ignore-daemonsets
On the worker01 node:
apt update
apt-get install -y kubeadm=1.21.0-00
kubeadm upgrade node --kubelet-version v1.21.0
apt-get install -y kubelet=1.21.0-00
Back on the master node:
root@master:~# kubectl uncordon worker01
root@master:~# kubectl get pods -o wide | grep nginx (make sure this is scheduled on node)
DEPLOYMENT CONTAINER_IMAGE READY_REPLICAS NAMESPACE
<deployment name> <container image> <ready replica count> <namespace>
DEPLOYMENT CONTAINER_IMAGE READY_REPLICAS NAMESPACE
deploy0 nginx:alpine 1 admin
show
Run the below command to get the correct output:
$ kubectl -n admin get deployment -o custom-columns=DEPLOYMENT:.metadata.name,CONTAINER_IMAGE:.spec.template.spec.containers[].image,READY_REPLICAS:.status.readyReplicas,NAMESPACE:.metadata.namespace --sort-by=.metadata.name > /opt/admin_data
- A kubeconfig file called admin.kubeconfig has been created in /root. There is something wrong with the configuration. Troubleshoot and fix it.
show
Make sure the port for the kube-apiserver is correct. Check if the port is 6443. Run the below command to know the cluster information:
$ kubectl cluster-info --kubeconfig /root/admin.kubeconfig
- Create a new deployment called nginx-deploy, with image nginx:1.16 and 1 replica. Next upgrade the deployment to version 1.17 using rolling update. Make sure that the version upgrade is recorded in the resource annotation.
show
Make use of the kubectl create command to create the deployment and explore the --record option while upgrading the deployment image. Run the below command to create a deployment nginx-deploy:
$ kubectl create deployment nginx-deploy --image=nginx:1.16
Run the below command to update the new image for nginx-deploy deployment and to record the version:
$ kubectl set image deployment/nginx-deploy nginx=nginx:1.17 --record
- A new deployment called alpha-deploy has been deployed in the alpha namespace. However, the pods are not running. Troubleshoot and fix the issue. The deployment should make use of the persistent volume alpha-pv to be mounted at /var/lib/mysql and should use the environment variable MYSQL_ALLOW_EMPTY_PASSWORD=1 to make use of an empty root password. Important: Do not alter the persistent volume.
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Use the command kubectl describe and try to fix the issue. Get the data of the PV alpha-pv and create appropriate PVC in namespace alpha. Solution manifest file to create a pvc called alpha-pvc as follows:
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: alpha-pvc
namespace: alpha
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: slow
show
Take a help of command etcdctl snapshot save --help options. Use documentaion which provide exact example.
export ETCDCTL_API=3
etcdctl snapshot save --cacert=/etc/kubernetes/pki/etcd/ca.crt --cert=/etc/kubernetes/pki/etcd/server.crt --key=/etc/kubernetes/pki/etcd/server.key --endpoints=127.0.0.1:2379 /opt/etcd-backup.db
- Create a pod called secret-1401 in the admin1401 namespace using the busybox image. The container within the pod should be called secret-admin and should sleep for 4800 seconds. The container should mount a read-only secret volume called secret-volume at the path /etc/secret-volume. The secret being mounted has already been created for you and is called dotfile-secret.
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Use the command kubectl run to create a pod definition file. Add secret volume and update container name in it. Alternatively, run the command:
kubectl run secret-1401 --image=busybox --dry-run=client -oyaml --command -- sleep 4800 > admin.yaml
Add the secret volume and mount path to create a pod called secret-1401 in the admin1401 namespace as follows:
---
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: secret-1401
name: secret-1401
namespace: admin1401
spec:
volumes:
- name: secret-volume
# secret volume
secret:
secretName: dotfile-secret
containers:
- command:
- sleep
args:
- "4800"
image: busybox
name: secret-admin
# volumes' mount path
volumeMounts:
- name: secret-volume
readOnly: true
mountPath: "/etc/secret-volume"
The same example is given in documentation, just copy/paste POD definition file
show
Use the command:
kubectl run nginx-pod --image=nginx:alpine
show
Use the command:
kubectl run messaging --image=redis:alpine -l tier=msg
show
Run the command:
kubectl create ns apx-1234
show
Run the command:
kubectl get nodes -o json > /opt/outputs/nodes.json
- Create a service messaging-service to expose the messaging application within the cluster on port 6379. Use imperative commands.
show
Run the command:
kubectl expose pod messaging --port=6379 --name messaging-service
show
Run the command:
kubectl create deployment web-app --image=nginx --replicas=2
- Create a static pod named static-box on the master node that uses the busybox image and the command sleep 1000.
show
Create a pod definition file in the manifests directory. For that use command
kubectl run --restart=Never --image=busybox static-box --dry-run=client -o yaml --command -- sleep 1000 > /etc/kubernetes/manifests/static.yaml
show
Run the command:
kubectl run temp-bus --image=redis:alpine --namespace=admin --restart=Never
- Expose the web-app as service web-app-service application on port 30082 on the nodes on the cluster. The web application listens on port 8080.
show
Run the command:
kubectl expose deployment web-app --type=NodePort --port=8080 --name=web-app-service --dry-run=client -o yaml > web-app-service.yaml
to generate a service definition file. Now, in generated service definition file add the nodePort field with the given port number under the ports section and create a service.
- Use JSON PATH query to retrieve the osImages of all the nodes and store it in a file /opt/outputs/nodes_os.txt. The osImages are under the nodeInfo section under status of each node.
show
Run the command:
kubectl get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}' > /opt/outputs/nodes_os.txt
* Volume Name: pv-test
* Storage: 100Mi
* Access modes: ReadWriteMany
* Host Path: /pv/data-test
show
Solution manifest file to create a persistent volume pv-test as follows:
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv-test
spec:
capacity:
storage: 100Mi
volumeMode: Filesystem
accessModes:
- ReadWriteMany
hostPath:
path: /pv/data-test
- Create a Pod called redis-storage with image redis:alpine with a Volume of type emptyDir that lasts for the life of the Pod. Spec sare:
* Pod named 'redis-storage' created
* Pod 'redis-storage' uses Volume type of emptyDir
* Pod 'redis-storage' uses volumeMount with mountPath = /data/redis
show
Use the command kubectl run and create a pod definition file for redis-storage pod and add volume. Alternatively, run the command:
kubectl run redis-storage --image=redis:alpine --dry-run=client -oyaml > redis-storage.yaml
and add volume emptyDir in it. Solution manifest file to create a pod redis-storage as follows:
---
apiVersion: v1
kind: Pod
metadata:
labels:
run: redis-storage
name: redis-storage
spec:
containers:
- image: redis:alpine
name: redis-storage
volumeMounts:
- mountPath: /data/redis
name: temp-volume
volumes:
- name: temp-volume
emptyDir: {}
- Create a new pod called super-user with image busybox. Allow the pod to be able to set system_time. The container should sleep for 4800 seconds.
show
Solution manifest file to create a pod super-user-pod as follows:
---
apiVersion: v1
kind: Pod
metadata:
labels:
run: super-user
name: super-user
spec:
containers:
- command:
- sleep
- "4800"
image: busybox
name: super-user
securityContext:
capabilities:
add: ["SYS_TIME"]
dnsPolicy: ClusterFirst
restartPolicy: Always
- A pod definition file is created at /root/use-pv.yaml. Make use of this manifest file and mount the persistent volume called pv-1. Ensure the pod is running and the PV is bound. Specs are:
mountPath: /data
persistentVolumeClaim Name: my-pvc
Add a persistentVolumeClaim definition to pod definition file.
show
Solution manifest file to create a pvc my-pvc as follows:
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: my-pvc
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Mi
And then, update the pod definition file as follows:
---
apiVersion: v1
kind: Pod
metadata:
labels:
run: use-pv
name: use-pv
spec:
containers:
- image: nginx
name: use-pv
volumeMounts:
- mountPath: "/data"
name: mypd
volumes:
- name: mypd
persistentVolumeClaim:
claimName: my-pvc
Finally, create the pod by running: kubectl create -f /root/use-pv.yaml
- Create a new user called john. Grant him access to the cluster. John should have permission to create, list, get, update and delete pods in the development namespace . The private key exists in the location: /root/john.key and csr at /root/john.csr. Important Note: As of kubernetes 1.19, the CertificateSigningRequest object expects a signerName.
show
Solution manifest file to create a CSR as follows:
---
apiVersion: certificates.k8s.io/v1
kind: CertificateSigningRequest
metadata:
name: john-developer
spec:
signerName: kubernetes.io/kube-apiserver-client
request: <create a requested data using cmd 'cat <csr file_name> | base64 | tr -d "\n"'
usages:
- digital signature
- key encipherment
- client auth
groups:
- system:authenticated
To approve this certificate, run:
kubectl certificate approve john-developer
Next, create a role developer and rolebinding developer-role-binding, run the command:
kubectl create role developer --resource=pods --verb=create,list,get,update,delete --namespace=development
kubectl create rolebinding developer-role-binding --role=developer --user=john --namespace=development
To verify the permission from kubectl utility tool:
kubectl auth can-i update pods --as=john --namespace=development
- Create a nginx pod called nginx-resolver using image nginx, expose it internally with a service called nginx-resolver-service. Test that you are able to look up the service and pod names from within the cluster. Use the image busybox for dns lookup. Record results in /root/nginx.svc and /root/nginx.pod.
show
Use the command kubectl run and create a nginx pod and busybox pod. Resolve it, nginx service and its pod name from busybox pod. To create a pod nginx-resolver and expose it internally:
kubectl run nginx-resolver --image=nginx
kubectl expose pod nginx-resolver --name=nginx-resolver-service --port=80 --target-port=80 --type=ClusterIP
Then create a pod test-nslookup. Test that you are able to look up the service and pod names from within the cluster:
kubectl run test-nslookup --image=busybox --rm -it --restart=Never -- nslookup nginx-resolver-service
kubectl run test-nslookup --image=busybox --rm -it --restart=Never -- nslookup nginx-resolver-service > /root/nginx.svc
Get the IP of the nginx-resolver pod and replace the dots(.) with hyphon(-) which will be used below.
kubectl get pod nginx-resolver -o wide
kubectl run test-nslookup --image=busybox --rm -it --restart=Never -- nslookup <P-O-D-I-P.default.pod> > /root/nginx.pod
- Create a static pod on worker01 called nginx-critical with image nginx and make sure that it is recreated/restarted automatically in case of a failure.
show
Use /etc/kubernetes/manifests as the Static Pod path for example To create a static pod called nginx-critical by using below command:
kubectl run nginx-critical --image=nginx --dry-run=client -o yaml > static.yaml
Copy the contents of this file or use scp command to transfer this file from master to worker01 node.
root@master:~# scp static.yaml worker01:/root/
To know the IP Address of the worker01 node:
root@master:~# kubectl get nodes -o wide
To rerform SSH:
root@master:~# ssh worker01
OR
root@master:~# ssh <IP of worker01>
On worker01 node: Check if static pod directory is present which is /etc/kubernetes/manifests, if it's not present then create it.
root@worker01:~# mkdir -p /etc/kubernetes/manifests
Add that complete path to the staticPodPath field in the kubelet config.yaml file.
root@worker01:~# vi /var/lib/kubelet/config.yaml
Now, move/copy the static.yaml to path /etc/kubernetes/manifests/.
root@worker01:~# cp /root/static.yaml /etc/kubernetes/manifests/
Go back to the master node and check the status of static pod:
root@worker01:~# exit
logout
root@master:~# kubectl get pods -o wide
- Create a new service account with the name pvviewer. Grant this Service account access to list all PersistentVolumes in the cluster by creating an appropriate cluster role called pvviewer-role and ClusterRoleBinding called pvviewer-role-binding. Next, create a pod called pvviewer with the image redis and serviceAccount: pvviewer in the default namespace.
show
Create a service account pvviewer:
kubectl create serviceaccount pvviewer
To create a clusterrole:
kubectl create clusterrole pvviewer-role --resource=persistentvolumes --verb=list
To create a clusterrolebinding:
kubectl create clusterrolebinding pvviewer-role-binding --clusterrole=pvviewer-role --serviceaccount=default:pvviewer
Solution manifest file to create a new pod called pvviewer as follows:
---
apiVersion: v1
kind: Pod
metadata:
labels:
run: pvviewer
name: pvviewer
spec:
containers:
- image: redis
name: pvviewer
# Add service account name
serviceAccountName: pvviewer
- List the InternalIP of all nodes of the cluster. Save the result to a file /root/node_ips. Answer should be in the format: InternalIP of master<space>InternalIP of worker01 (in a single line).
show
Explore the JSON PATH
kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="InternalIP")].address}' > /root/node_ips
Container 1, name: alpha, image: nginx
Container 2: name: beta, image: busybox, command: sleep 4800
Environment Variables:
container 1:
name: alpha
Container 2:
name: beta
show
Solution is:
---
apiVersion: v1
kind: Pod
metadata:
name: multi-pod
spec:
containers:
- image: nginx
name: alpha
env:
- name: name
value: alpha
- image: busybox
name: beta
command: ["sleep", "4800"]
env:
- name: name
value: beta
Specs are:
runAsUser: 1000
fsGroup: 2000
show
Solution manifest file to create a pod called non-root-pod as follows:
---
apiVersion: v1
kind: Pod
metadata:
name: non-root-pod
spec:
securityContext:
runAsUser: 1000
fsGroup: 2000
containers:
- name: non-root-pod
image: redis:alpine
Verify the user and group IDs by using below command:
kubectl exec -it non-root-pod -- id
- We have deployed a new pod called np-test and a service called np-test-service. Incoming connections to this service are not working. Troubleshoot and fix it. Create NetworkPolicy, by the name ingress-to-nptest that allows incoming connections to the service over port 80. Important: Don't delete any current objects deployed.
show
Solution manifest file to create a network policy ingress-to-nptest as follows:
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: ingress-to-nptest
namespace: default
spec:
podSelector:
matchLabels:
run: np-test
policyTypes:
- Ingress
ingress:
- ports:
- protocol: TCP
port: 80
- Taint the worker node worker01 to be Unschedulable. Once done, create a pod called dev-redis, image redis:alpine, to ensure workloads are not scheduled to this worker node. Finally, create a new pod called prod-redis and image redis:alpine with toleration to be scheduled on worker01.
key: env_type, value: production, operator: Equal and effect: NoSchedule
show
To add taints on the worker01 worker node:
kubectl taint node worker01 env_type=production:NoSchedule
Now, deploy dev-redis pod and to ensure that workloads are not scheduled to this worker01 worker node.
kubectl run dev-redis --image=redis:alpine
To view the node name of recently deployed pod:
kubectl get pods -o wide
Solution manifest file to deploy new pod called prod-redis with toleration to be scheduled on worker01 worker node.
---
apiVersion: v1
kind: Pod
metadata:
name: prod-redis
spec:
containers:
- name: prod-redis
image: redis:alpine
tolerations:
- effect: NoSchedule
key: env_type
operator: Equal
value: production
To view only prod-redis pod with less details:
kubectl get pods -o wide | grep prod-redis
- Create a pod called hr-pod in hr namespace belonging to the production environment and frontend tier, image redis:alpine. Use appropriate labels and create all the required objects if it does not exist in the system already. Create a namespace if it doesn't exist:
show
kubectl create namespace hr
and then create a hr-pod with given details:
kubectl run hr-pod --image=redis:alpine --namespace=hr --labels=environment=production,tier=frontend
- We have created a new deployment called nginx-deploy. Scale the deployment to 3 replicas. Has the replica's increased? Troubleshoot the issue and fix it.
show
Use the command kubectl scale to increase the replica count to 3.
kubectl scale deploy nginx-deploy --replicas=3
The controller-manager is responsible for scaling up pods of a replicaset. If you inspect the control plane components in the kube-system namespace, you will see that the controller-manager is not running.
kubectl get pods -n kube-system
The command running inside the controller-manager pod is incorrect. That's 'added' error. After fix all the values in the file and wait for controller-manager pod to restart. At last, inspect the deployment by using below command:
kubectl get deploy
- Create a job that calculates pi to 2000 decimal points using the container with the image named perl and the following commands issued to the container: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]. Once the job has completed, check the logs to and export the result to pi-result.txt.
show
kubectl job pi2000 --image=perl -o yaml --dry-run > pi2000.yaml
Then edit the file, edit the name, remove any ID references and include the command argument under container spec.
command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
So the manifest looks like:
apiVersion: batch/v1
kind: Job
metadata:
name: pi2000
spec:
template:
metadata:
creationTimestamp: null
spec:
containers:
- image: perl
name: pi2000
command: ["perl", "-Mbignum=bpi", "-wle", "print bpi(2000)"]
resources: {}
restartPolicy: Never
Then crate an object:
kubectl -f pi2000.yaml
And get the output from the logs and export them to text file
kubectl logs pi2000 > pi-result.txt
- Create a yaml file called nginx-deploy.yaml for a deployment of three replicas of nginx, listening on the container's port 80. They should have the labels role=webserver and app=nginx. The deployment should be named nginx-deploy. Expose the deployment with a load balancer and use a curl statement on the IP address of the load balancer
to export the output to a file titled output.txt.
show
kubectl run nginx-deploy --labels="role=webserver,app=nginx" --image=nginx --replicas=3 --port=80 -o yaml > nginx-deployment.yaml
Expose the deployment with a loadbalancer type, call it nginx-service
kubectl expose deployment nginx-deploy --type=LoadBalancer --name=nginx-service
Use a curl statement that connects to the IP endpoint of the nginx-service and save the output to a file called output.txt
curl IP > output.txt
show
kubectl scale deployment nginx-deploy --replicas=2
- Create a pod called haz-docs with an nginx image listening on port 80. Attach the pod to emptyDir storage, mounted to /tmp in the container. Connect to the pod and create a file with zero bytes in the /tmp directory called my-doc.txt.
show
---
apiVersion: apps/v1beta1
kind: Deployment
metadata:
labels:
run: haz-docs
name: haz-docs
spec:
replicas: 1
selector:
matchLabels:
run: haz-docs
strategy: {}
template:
metadata:
labels:
run: haz-docs
spec:
containers:
- image: nginx
name: haz-docs
volumeMounts:
- mountPath: /tmp
name: tmpvolume
ports:
- containerPort: 80
resources: {}
volumes:
- name: tmpvolume
emptyDir: {}
kubectl exec -it haz-docs-5b49cb4d87-2lm5g /bin/bash
root@haz-docs-5b49cb4d87-2lm5g:/# cd /tmp/
root@haz-docs-5b49cb4d87-2lm5g:/tmp# touch my-doc.txt
root@haz-docs-5b49cb4d87-2lm5g:/tmp# ls
my-doc.txt
show
kubectl label node worker01 rack=qa
apiVersion: v1
kind: Pod
metadata:
name: counter
spec:
containers:
- name: count
image: busybox
args: [/bin/sh, -c, 'i=0; while true; do echo "$i: $(date)"; i=$((i+1)); sleep 1; done']
- Start this pod. Once its logs exceed a count of 20 (no need to be precise — any time after it has reached 20 is fine), save the logs into a file in your home directory called count.result.txt.
show
kubectl apply -f counter.yaml
kubectl logs counter > count.result.txt
- Create a deployment with two replicas of nginx. The container listens on port 80. It should be named web-dep and be labeled with tier=frontend with an annotation of AppVersion=3.4. The containers must be running with the UID of 1000.
show
kubectl run web-dep --labels="tier=frontend" --image=nginx --replicas=2 --port=80 -o yaml > web-dep.yaml
Edit the file to add the annotation in the metadata section:
apiVersion: apps/v1beta1
kind: Deployment
metadata:
annotations:
AppVersion: "3.4"
creationTimestamp: 2019-03-02T18:17:19Z
generation: 1
labels:
tier: frontend
Create the deployment with kubectl apply command.
Output the description of the deployment to the file web-dep-description.txt
kubectl describe deploy/web-dep > web-dep-description.txt
show
kubectl --record deployment/web-dep set image deployment/web-dep nginx=nginx:1.9
- Roll the image in use by the web-dep deployment to the previous version. Do not set the version number of the image explicitly for this command.
show
kubectl rollout history deployment/web-dep
kubectl rollout undo deployment/web-dep
show
kubectl expose deployment/web-dep --type=NodePort
show
kubectl run testds --image=k8s.gcr.io/pause:2.0 -o yaml > testds.yaml
Then edited it as Daemonset to get it running, you don't do replicas in a daemonset, it runs on all nodes
show
apiVersion: v1
kind: ConfigMap
metadata:
name: kube-dns
namespace: kube-system
data:
stubDomains: |
{"acme.local": ["1.2.3.4"]}
upstreamNameservers: |
["8.8.8.8", "8.8.4.4"]
- An app inside a container needs the IP address of the web-dep endpoint to be passed to it as an environment variable called ULTIMA. Save the yaml as env-ultima.yaml.
show
Get the IP address of the web-dep service
kubectl get svc
Create a mainfest file:
---
apiVersion: apps/v1beta2
kind: Deployment
metadata:
name: ultima-dep
namespace: default
spec:
selector:
matchLabels:
app: ultima-app
template:
metadata:
labels:
app: ultima-app
spec:
containers:
- name: pause-pod
image: k8s.gcr.io/pause:2.0
env:
- name: ULTIMA
value: 55.55.58.23
Finally, create a deployment
kubectl -f env-ultima.yaml
- Figure out a way to create a pod with 3 replicas using the the nginx container that can have pods deployed on a worker node and the master node if needed.
show
kubectl get nodes
kubectl describe node MASTERNODE
Notice the taint on the master node:
Taints: node-role.kubernetes.io/master:NoSchedule
Add the toleration to the yaml file:
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx
namespace: default
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx
tolerations:
- key: "node-role.kubernetes.io/master"
operator: "Equal"
effect: "NoSchedule"
- Create a yaml file called db-secret.yaml for a secret called db-user-pass. The secret should have two fields: a username and password. The username should be superadmin and the password should be imamazing.
show
echo -n 'superadmin' > ./username.txt
echo -n 'imamazing' > ./password.txt
kubectl create secret generic db-user-pass --from-file=./username.txt --from-file=./password.txt -o yaml > db-secret.yaml
apiVersion: v1 data: password.txt: aWhlYXJ0a2l0dGVucw== username.txt: YWRtaW4= kind: Secret metadata: creationTimestamp: 2019-03-03T00:21:16Z name: db-user-pass namespace: default resourceVersion: "30182" selfLink: /api/v1/namespaces/default/secrets/db-user-pass uid: 42b979da-3d4a-11e9-8f41-06f514f6b3f0 type: Opaque
</p>
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