DaemonSet — how does it work?

A DaemonSet in Kubernetes ensures that a copy of a pod runs on each (or selected) node in the cluster. Its working logic is as follows:

• When a DaemonSet is created, Kubernetes guarantees that one instance of the pod will be running on each node.
• If a new node is added to the cluster, the DaemonSet automatically creates a pod on it.
• If a node is removed, the corresponding pod is also removed.
• This is useful for running system agents, monitoring, logging, and other services that need to operate on all nodes.

Example of a DaemonSet manifest:

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: example-daemonset
spec:
  selector:
    matchLabels:
      name: example
  template:
    metadata:
      labels:
        name: example
    spec:
      containers:
      - name: example-container
        image: busybox
        command: ["sleep", "3600"]

Thus, the DaemonSet ensures the continuous presence of pods on all nodes, which is important for system tasks.