DaemonSet¶

Concept and Usage of DaemonSet¶

DaemonSet will ensure that all or some Nodes will run a copy of a Pod. Whenever a new Node is added to the cluster, a Pod is automatically added to that Node. When a Node is removed from the cluster, the Pod will be automatically removed as well. Remember, DaemonSet uses the default scheduler and node affinity rules to schedule the pods on the nodes.

Use cases;

• Running a logging agent (collector) on all nodes
• Running a monitoring agent on all nodes
• Setting up network services like firewall, load-balancer, network proxies, VPN on all nodes

For example, we know that kube-proxy is required on every node to provide network services. Therefore, kube-proxy component is actually deployed as a DaemonSet in Kubernetes.

flowchart TB
    subgraph Cluster
        direction TB
        N1[Node 1] --> P1(Pod)
        N2[Node 2] --> P2(Pod)
    end

    P1:::daemonset
    P2:::daemonset
    subgraph DaemonSet
      direction LR
      PDS(Pod Definition)
      PDS --> P1
      PDS --> P2
    end

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: sample-daemonset
spec:
  selector:
    matchLabels:
      app: sample-agent
  template:
    metadata:
      labels:
        app: sample-agent
    spec:
      containers:
        - name: sample-monitoring-agent
          image: sample-monitoring-agent-image

kubectl get daemonsets