StatefulSet Manifest Validation

StatefulSet Configuration

StatefulSets manage stateful applications that need stable network identities and persistent storage. They have specific requirements beyond standard Deployments.

Example StatefulSet

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgres
  labels:
    app: postgres
spec:
  serviceName: postgres-headless
  replicas: 3
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      securityContext:
        runAsNonRoot: true
        runAsUser: 999
        fsGroup: 999
      containers:
        - name: postgres
          image: postgres:16.1
          ports:
            - containerPort: 5432
              name: postgres
          resources:
            requests:
              cpu: 500m
              memory: 1Gi
            limits:
              cpu: 2000m
              memory: 2Gi
          livenessProbe:
            exec:
              command: ["pg_isready", "-U", "postgres"]
            initialDelaySeconds: 30
            periodSeconds: 10
          readinessProbe:
            exec:
              command: ["pg_isready", "-U", "postgres"]
            initialDelaySeconds: 5
            periodSeconds: 5
          volumeMounts:
            - name: data
              mountPath: /var/lib/postgresql/data
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: ["ReadWriteOnce"]
        resources:
          requests:
            storage: 10Gi

StatefulSet Specifics

Field	Purpose	Important Because
serviceName	Headless Service for DNS	Required for stable network IDs
volumeClaimTemplates	Per-pod PVC creation	Data persists across restarts
podManagementPolicy	OrderedReady or Parallel	Controls rollout order
updateStrategy	RollingUpdate or OnDelete	Controls update behavior

Key Differences from Deployments

• Pods get stable hostnames: <name>-0, <name>-1, etc.
• Pods are created and deleted in order (by default)
• PVCs are not deleted when StatefulSet is deleted
• A headless Service (clusterIP: None) is needed for DNS records

The validator checks StatefulSet containers just like Deployment containers — resource limits, probes, security context, and image tags all apply equally.