Kubernetes CKA sample exam question 57 with answer

Question
SSH into master node with ssh cluster2-master1. Temporary stop the kube-scheduler, this means in a way you can start it again afterwards.
Create a single pod name manual-schedule of image httpd:2.4-alpine, confirm it's created, but not scheduled on any node.
Now, you're the scheduler and have all its power, manually schedule that pod on a node cluster2-master1. Make sure it's running.
Start the kube-scheduler again and confirm that it's running correctly by creating a pod named manual-schedule2 of image httpd:2.4-alpine and check if it's running on cluster2-worker1.

Answer
SSH to master node:

ssh cluster2-master1

Check the pods in kube-system namespace:

kubectl -n kube-system get po

Can be noticed kube-scheduler running as static pod. Move it's manifest to other location:

cd /etc/kubernetes/manifests
mv kube-scheduler.yaml /etc/kubernetes

And check again the pods. Now the kube-scheduler pod shouldn't be running:

kubectl -n kube-system get po

Run first pod:

kubectl run manual-schedule --image=httpd:2.4-alpine

Check the pod status:

kubectl get po manual-schedule

it should be in Pending state, because there is no scheduler to place it on a node
Edit the manifest:

kubectl edit po manual-schedule

And manually schedule the pod by adding nodeName under spec:

...
spec:
  nodeName: cluster2-master1
...

Replace the current pod:

kubectl replace --force -f /tmp/kubectl-123456789.yaml

And check:

kubectl get po manual-schedule -o wide

now it should be running on cluster2-master1.
Start again the kube-scheduler static pod:

mv /etc/kubernetes/kube-scheduler.yaml /etc/kubernetes/manifests

Check the status and wait until it is running:

kubectl -n kube-system get po -w

Run second pod:

kubectl run manual-schedule2 --image=httpd:2.4-alpine

And check:

kubectl get po manual-schedule2 -o wide

it should be running on cluster2-worker1 node