DaemonSets

A DaemonSet is another controller-backed Object that is similar to a ReplicaSet but aims at running exactly one templated Pod replica per node in the cluster (optionally matching selectors). The most common use cases for running a DaemonSet are as follows:

• Managing monitoring telemetry for a given cluster node, for example, running Prometheus Node Exporter
• Running a log collection daemon on each node, for example, fluentd or logstash
• Running troubleshooting Pods, for example, node-problem-detector (https://github.com/kubernetes/node-problem-detector)

One of the DaemonSets that may run on your cluster out of the box is kube-proxy. In a standard cluster deployment performed by kubeadm, kube-proxy is distributed to nodes as a DaemonSet. You can also verify this on your Katacoda playground:

master $ kubectl get daemonset --all-namespaces
NAMESPACE     NAME         DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
kube-system   kube-proxy   2         2         2       2            2           <none>          12m
kube-system   weave-net    2         2         2       2            2           <none>          12m

If you would like to find out more about DaemonSets, please refer to the official documentation: https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/.