StatefulSets
StatefulSets are used for managing stateful applications that require stable network identities and persistent storage. They:
- Provide guarantees about the ordering and uniqueness of Pods Maintain a sticky identity for each Pod
- Offer stable, persistent storage
- Support ordered, graceful deployment and scaling
Use cases: Databases, distributed systems like Cassandra or Elasticsearch
DaemonSets
DaemonSets ensure that all (or some) nodes run a copy of a Pod. As nodes are added to the cluster, Pods are added to them. They are used for:
- Running a cluster storage daemon on every node
- Running a logs collection daemon on every node
- Running a node monitoring daemon on every node
Use cases: Node-level operations, cluster-wide services like log collection or monitoring
ReplicaSets (RS)
ReplicaSets maintain a stable set of replica Pods running at any given time. They:
- Ensure a specified number of Pod replicas are running
- Provide high availability by creating and deleting Pods as needed
- Allow easy scaling of applications
Note: While ReplicaSets can be used directly, it’s generally recommended to use Deployments, which manage ReplicaSets and provide declarative updates to Pods. Use cases: Stateless applications, web servers, microservices