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.

daemonsets.yaml

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

Resource Requirements and Limits Job