Listen to this Post
Kubernetes DaemonSets ensure that a specific pod runs on every node (or selected nodes) in the cluster. They are ideal for deploying node-level agents like log collectors, monitoring agents, or network plugins.
Read the full article here: Kubernetes DaemonSets – Run on Every Node
You Should Know:
1. Creating a DaemonSet
A basic DaemonSet YAML configuration:
apiVersion: apps/v1 kind: DaemonSet metadata: name: fluentd-logging namespace: kube-system labels: k8s-app: fluentd-logging spec: selector: matchLabels: name: fluentd-logging template: metadata: labels: name: fluentd-logging spec: tolerations: - key: node-role.kubernetes.io/master effect: NoSchedule containers: - name: fluentd image: fluent/fluentd-kubernetes-daemonset:v1-debian-elasticsearch resources: limits: memory: 200Mi requests: cpu: 100m memory: 200Mi volumeMounts: - name: varlog mountPath: /var/log terminationGracePeriodSeconds: 30 volumes: - name: varlog hostPath: path: /var/log
2. Verifying DaemonSet Deployment
Check DaemonSet status:
kubectl get daemonset -n kube-system
View pods running on each node:
kubectl get pods -n kube-system -o wide
3. Updating a DaemonSet
Rolling update for a DaemonSet:
kubectl rollout restart daemonset <daemonset-name> -n <namespace>
4. Deleting a DaemonSet
Remove a DaemonSet:
kubectl delete daemonset <daemonset-name> -n <namespace>
5. Node Selectors & Taints/Tolerations
To restrict DaemonSets to specific nodes:
nodeSelector: disktype: ssd
For tainted nodes (e.g., master nodes):
tolerations: - key: "node-role.kubernetes.io/master" operator: "Exists" effect: "NoSchedule"
6. Monitoring DaemonSets
Check DaemonSet events:
kubectl describe daemonset <daemonset-name> -n <namespace>
What Undercode Say:
DaemonSets are crucial for cluster-level operations, ensuring essential services like logging (fluentd), monitoring (Prometheus Node Exporter), or networking (Calico) run on every node. Use `kubectl` commands to manage them efficiently, and leverage `nodeSelector` and `tolerations` for granular control. Always verify deployments and monitor resource usage to avoid node congestion.
Expected Output:
$ kubectl get daemonset -n kube-system NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE fluentd-logging 3 3 3 3 3 <none> 2d
For further reading:
References:
Reported By: Sandip Das – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
