What is a DaemonSet in Kubernetes?

A DaemonSet in Kubernetes is designed to ensure that a copy of a Pod runs on all nodes in a cluster or on a specific subset of nodes. This is particularly useful for running background processes or services on each node, such as log collection agents, monitoring agents, or network proxies, which need to be present on every node to perform their functions effectively.

By using a DaemonSet, Kubernetes simplifies the deployment and management of these types of applications. When new nodes are added to the cluster, the DaemonSet automatically schedules the Pods on those nodes, maintaining the desired state of having a Pod running on each node.

The other options do not accurately describe the function of a DaemonSet. For instance, while stateful applications might use StatefulSets for deployment, a DaemonSet is not focused on managing stateful applications. Additionally, scaling applications is typically the role of Deployments, not DaemonSets. Lastly, while a DaemonSet can run on master nodes, its purpose is not restricted to them, and it is not defined as an agent specifically for that role. Thus, the defining characteristic of a DaemonSet is ensuring a consistent presence of Pods across all or selected nodes in the cluster.