StatefulSet Basics

StatefulSet is built for databases and queues. The key idea is stable identity plus stable storage.

Typical features

• Fixed Pod names (like mysql-0)
• One PVC per Pod
• Ordered startup and rolling updates

Core snippet

spec:
  serviceName: mysql
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: ["ReadWriteOnce"]
        resources:
          requests:
            storage: 10Gi

Tips

• Pair with a Headless Service
• Validate with a single replica before scaling

Practical notes

• Start with a quick inventory: kubectl get nodes, kubectl get pods -A, and kubectl get events -A.
• Compare desired vs. observed state; kubectl describe usually explains drift or failed controllers.
• Keep names, labels, and selectors consistent so Services and controllers can find Pods.

Quick checklist

• The resource matches the intent you described in YAML.
• Namespaces, RBAC, and images are correct for the target environment.
• Health checks and logs are in place before promotion.

References

• StatefulSets
• Stateful Applications