Solution:1
You need to add targetPort on the mysql service yaml definition.
apiVersion: v1
kind: Service
metadata:
name: db
labels:
name: db-service
app: demo-wordpress-app
spec:
ports:
– port: 3306
targetPort: 3306
selector:
name: mysql-app-label
Solution:2
include below line in mysql service YAML
targetPort: 3306