WordPress + MySQL deployed in Kubernetes – MySQL Connection Error

Solution:

After testing different images for Mysql and WordPress and reading useful links on hub.docker.com mysql & wordpress i got the web application stack working.

The configuration:

MySQL:

apiVersion: v1
kind: Service
metadata:
name: wordpress-mysql
  labels:
    app: wordpress
spec:
  ports:
    - port: 3306
  selector:
    app: wordpress
    tier: mysql
  clusterIP: None

---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: local-storage
  resources:
    requests:
      storage: 1Gi

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: wordpress-mysql
  labels:
    app: wordpress
spec:
  selector:
    matchLabels:
      app: wordpress
      tier: mysql
  replicas: 1
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: wordpress
        tier: mysql
    spec:
      containers:
      - image: mysql:5.7
        imagePullPolicy: IfNotPresent
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: root-pass
              key: password

        - name: MYSQL_DATABASE
          value: mysql

        - name: MYSQL_USER
          value: mysql

        - name: MYSQL_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-pass
              key: password

        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      nodeSelector:
        storage: local
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: mysql-pv-claim

WordPress:

apiVersion: v1
kind: Service
metadata:
  name: wordpress
  labels:
    app: wordpress
spec:
  ports:
    - port: 80
  selector:
    app: wordpress
    tier: frontend
  type: LoadBalancer
  externalIPs:
  - 192.168.1.83

---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: wp-pv-claim
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: local-storage
  resources:
    requests:
      storage: 1Gi

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: wordpress
  labels:
    app: wordpress
spec:
  selector:
    matchLabels:
      app: wordpress
      tier: frontend
  replicas: 1
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: wordpress
        tier: frontend
    spec:
      containers:
      - image: wordpress
        name: wordpress
        imagePullPolicy: IfNotPresent

        env:
        - name: WORDPRESS_DB_HOST
          value: wordpress-mysql

        - name: WORDPRESS_DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-pass
              key: password

        - name: WORDPRESS_DB_USER
          value: mysql

        - name: WORDPRESS_DB_NAME
          value: mysql

        ports:
        - containerPort: 80
          name: wordpress
        volumeMounts:
        - name: wordpress-persistent-storage
          mountPath: /var/www/html
      nodeSelector:
        storage: local
      volumes:
      - name: wordpress-persistent-storage
        persistentVolumeClaim:
          claimName: wp-pv-claim

Output PersitentVolume:

NAME             STATUS   VOLUME                        CAPACITY   ACCESS MODES   STORAGECLASS    
mysql-pv-claim   Bound    persistent-volume-mysql       4Gi        RWO            local-storage   
wp-pv-claim      Bound    persistent-volume-wordpress   2Gi        RWO            local-storage   

Secrets:

apiVersion: v1
kind: Secret
metadata:
  name: root-pass
  namespace: default
data:
  password: cGFzc3dvcmQ=
type: Opaque

---

apiVersion: v1
kind: Secret
metadata:
  name: mysql-pass
  namespace: default
data:
  password: cGFzc3dvcmQ=
type: Opaque

Notes for my example configuration:

• on node1 created directory /mysql/data & /wordpress/data (mount point for mysql and wordpress containers).
• image used for mysql -> mysql:5.7
• image used for wordpress -> wordpress
• added environment variables according to the documentation of mysql and wordpress.