StatefulSets for stateful applications in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a StatefulSet in Kubernetes?

A StatefulSet is a Kubernetes resource used to manage stateful applications. It ensures that pods have stable, unique network IDs and persistent storage, keeping their state across restarts.

intermediate

How does a StatefulSet differ from a Deployment?

Unlike Deployments, StatefulSets provide stable pod identities and persistent storage. Deployments are for stateless apps where pods are interchangeable, but StatefulSets keep pods ordered and unique.

beginner

What is the role of PersistentVolumeClaims (PVCs) in StatefulSets?

Each pod in a StatefulSet gets its own PersistentVolumeClaim, which provides stable storage that remains even if the pod is deleted or rescheduled. This keeps the pod's data safe.

intermediate

Explain the importance of stable network identities in StatefulSets.

Stable network IDs let each pod keep the same hostname and network identity even after restarts. This is important for apps like databases that need to recognize each other consistently.

intermediate

What happens when you scale down a StatefulSet?

When scaling down, pods are terminated in reverse order (highest ordinal first). Their storage remains, so if scaled back up, pods keep their data and identity.

Which Kubernetes resource is best for managing stateful applications?

A ReplicaSet

B Deployment

C DaemonSet

D StatefulSet

StatefulSet is designed for stateful apps needing stable identities and storage.

What does a StatefulSet guarantee for its pods?

A Random pod names and ephemeral storage

B Stable network IDs and persistent storage

C No storage and no network identity

D Pods are always scheduled on the same node

StatefulSets give pods stable network IDs and persistent storage.

How are pods terminated when scaling down a StatefulSet?

A In reverse ordinal order (highest number first)

B Random order

C In creation order (lowest number first)

D All at once

Pods are terminated starting from the highest ordinal number.

What is the purpose of PersistentVolumeClaims in StatefulSets?

A To provide stable storage for each pod

B To assign IP addresses

C To schedule pods on nodes

D To manage pod replicas

PVCs provide persistent storage that stays with each pod.

Which feature is NOT provided by StatefulSets?

A Stable pod hostnames

B Persistent storage

C Automatic load balancing

D Ordered pod deployment

Load balancing is handled by Services, not StatefulSets.

Describe how StatefulSets manage pod identity and storage for stateful applications.

Think about what makes stateful apps different from stateless ones.

Explain the difference between a Deployment and a StatefulSet in Kubernetes.

Focus on pod identity and storage.