How to Run MySQL, PostgreSQL & MongoDB on Kubernetes: A Step‑by‑Step Guide

Key Concepts for Running Databases on Kubernetes

Databases are stateful workloads that require persistent storage, backup, high availability, and stable network identities. Kubernetes, originally designed for stateless apps, can run databases safely by using StatefulSets, PersistentVolumes (PV), PersistentVolumeClaims (PVC), and StorageClasses.

StatefulSets

StatefulSet is a Kubernetes resource for managing stateful applications such as databases. It ensures each pod has stable network identity and persistent storage.

Persistent storage: Uses PVs so each pod retains data after restarts.

Stable network identifiers: Each pod receives a unique, consistent name (e.g., mypod-0).

Tutorial: Create a Database on Kubernetes

Step 1: Create a StorageClass (if needed)

Define a StorageClass to provision volumes dynamically. Example for AWS EKS:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp3
reclaimPolicy: Retain

Apply with kubectl apply -f storage-class.yaml.

Step 2: Create a PersistentVolume (PV)

apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: standard
  hostPath:
    path: /mnt/data

Step 3: Create a PersistentVolumeClaim (PVC)

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: standard

Step 4: Deploy MySQL StatefulSet

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: "mysql"
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
        - name: mysql
          image: mysql:5.7
          ports:
            - containerPort: 3306
              name: mysql
          env:
            - name: MYSQL_ROOT_PASSWORD
              value: "your_password"
          volumeMounts:
            - name: mysql-storage
              mountPath: /var/lib/mysql
  volumeClaimTemplates:
    - metadata:
        name: mysql-storage
      spec:
        accessModes: [ "ReadWriteOnce" ]
        resources:
          requests:
            storage: 10Gi
        storageClassName: standard

Step 5: Create a Headless Service for MySQL

# Headless service
apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
spec:
  ports:
    - name: mysql
      port: 3306
  selector:
    app: mysql

Step 6: Ship MySQL Logs to Monitoring Tools

Configure MySQL to forward slow‑query, error, and general logs to systems such as Datadog, Grafana, Prometheus, or the ELK stack for performance analysis.

Step 7: Perform Regular Backups and Restores

Use tools like Velero to back up PVs and restore them, ensuring data durability. Velero provides cluster backup, disaster recovery, and scheduled backup capabilities.

Step 8: Configure Database Alerts

Set up alerting with Datadog, Nagios, Prometheus, or Grafana and integrate with Slack or PagerDuty to receive notifications on performance issues or failures.

Conclusion

Running databases on Kubernetes introduces challenges around state management, persistent storage, and network stability, but by leveraging PersistentVolumes, StorageClasses, StatefulSets, and PVCs, operators can ensure data integrity and high availability.