CKAD field manual

k8s DaemonSet YAML example

A DaemonSet puts one Pod on every matching node. New node → new Pod. Gone node → Pod gone.

YAML then apply

kubectl create deploy agent --image=nginx:1.27 -o yaml --dry-run=client > ds.yaml
# kind: DaemonSet — delete replicas and strategy
kubectl apply -f ds.yaml

YAML

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: agent
  namespace: default
spec:
  selector:
    matchLabels:
      app: agent
  template:
    metadata:
      labels:
        app: agent
    spec:
      containers:
        - name: nginx
          image: nginx:1.27

Subset of nodes

spec:
  template:
    spec:
      nodeSelector:
        disk: ssd
      tolerations:
        - key: node-role.kubernetes.io/control-plane
          operator: Exists
          effect: NoSchedule
      containers:
        - name: shipper
          image: busybox:1.36
          command: ["sleep", "1d"]
          volumeMounts:
            - name: varlog
              mountPath: /var/log
      volumes:
        - name: varlog
          hostPath:
            path: /var/log

Rollout

kubectl set image ds/agent nginx=nginx:1.28
kubectl rollout status ds/agent
kubectl rollout history ds/agent
kubectl rollout undo ds/agent
kubectl get ds,po -l app=agent -o wide
kubectl drain node-1 --ignore-daemonsets --delete-emptydir-data

Fields

selector: Must match template.metadata.labels. Immutable after create.
template: The Pod. There is no replicas field — one per matching node.
nodeSelector: Only matching nodes get a Pod. Omit it for every Ready node.
tolerations: Tainted nodes (control-plane) stay empty without these.
updateStrategy: RollingUpdate is the default. OnDelete waits until you delete each Pod.
hostPath: The node filesystem. Typical for log agents. Path is on the node, not in the image.
replicas: Not a DaemonSet field. Delete it if you dry-run a Deployment.
kubectl create deploy: No DaemonSet generator. Dry-run a Deployment, then kind: DaemonSet and drop replicas.
kubectl rollout: Works on a DaemonSet the same as a Deployment.

Watch

No replicas field. One Pod per matching node. A new node gets a Pod; a gone node loses it.
selector.matchLabels and template.metadata.labels must match. The selector is immutable after create.
There is no kubectl create daemonset. Dry-run a Deployment, set kind: DaemonSet, delete replicas and strategy.

Official docs DaemonSets

Practice these objects on a live cluster →