Cloud Intermediate

Kubernetes — Stateful Workloady v Praxi¶

KubernetesStatefulSetDatabasesStorage 6 min read

Provoz stateful aplikací na Kubernetes. Databáze, message brokery, storage classes a data persistence.

Stateful vs Stateless¶

• Stabilní hostname — mysql-0, mysql-1
• Ordered deployment — 0 → 1 → 2
• Stable storage — PVC per pod
• Headless Service — DNS per pod

PostgreSQL StatefulSet¶

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgresql
spec:
  serviceName: postgresql
  replicas: 3
  template:
    spec:
      containers:
        - name: postgres
          image: postgres:16-alpine
          ports:
            - containerPort: 5432
          env:
            - name: PGDATA
              value: /var/lib/postgresql/data/pgdata
          volumeMounts:
            - name: data
              mountPath: /var/lib/postgresql/data
          resources:
            requests:
              cpu: 500m
              memory: 1Gi
          livenessProbe:
            exec:
              command: ["pg_isready", "-U", "postgres"]
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: [ReadWriteOnce]
        storageClassName: fast-ssd
        resources:
          requests:
            storage: 100Gi

Doporučené Operátory¶

• CloudNativePG — PostgreSQL (CNCF sandbox)
• Percona Operators — MySQL, MongoDB, PostgreSQL
• Strimzi — Apache Kafka
• Redis Operator — Spotahome

Operátory řeší: failover, backup, restore, upgrades, connection pooling, monitoring.

Storage Best Practices¶

• reclaimPolicy: Retain pro data
• SSD StorageClass pro databáze
• CSI VolumeSnapshot pro point-in-time recovery
• Nepoužívejte ReadWriteMany pro databáze
• Testujte disaster recovery scénáře

Summary¶

Stateful workloady na K8s jsou production-ready. Preferujte operátory a vždy testujte failover a restore.

Need Help with Implementation?¶

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