Solution

2 minutes read

Create a Deployment named web-app with 6 replicas using nginx:1.26 image

kubectl create deployment web-app --image=nginx:1.26 --replicas=6

Create a DaemonSet named monitoring using nginx:alpine image

kubectl create -f - <<EOF
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: monitoring
spec:
  selector:
    matchLabels:
      app: monitoring
  template:
    metadata:
      labels:
        app: monitoring
    spec:
      containers:
      - name: monitoring
        image: nginx:alpine
        ports:
        - containerPort: 80
EOF

Check how Pods are distributed across all Nodes

kubectl get pods -o wide

You should see Pods are distributed across worker Nodes, and one monitoring Pod per Node.

You need to perform maintenance on worker1. First, cordonthis Node to prevent new Pods from being scheduled on it

kubectl cordon worker1

Verify that worker1 is cordoned, but existing Pods are still running

worker1 should show as Ready,SchedulingDisabled

kubectl get nodes

existing Pods on worker1 should still be running

kubectl get pods -o wide

Drain worker1 to move all Pods to other nodes

kubectl drain worker1 --ignore-daemonsets --delete-emptydir-data --force

--ignore-daemonsets flag is needed because DaemonSet Pods cannot be moved
--delete-emptydir-data flag ensures that Pods with emptydir volumes can be deleted
--force flag ensures Pods that are not managed by a controller can be destroyed

Verify all web-app Pods have been moved out of worker1, while DaemonSet Pods are still running

kubectl get pods -o wide

Make worker1 available for scheduling again

kubectl uncordon worker1

Force the restart of the web-app deployment and verify some Pods are scheduled on worker1

kubectl rollout restart deployment/web-app
kubectl get pods -o wide

You should notice that some Pods are scheduled on worker1.

Clean up all resources

kubectl delete deployment web-app
kubectl delete daemonset monitoring