I got a web server in spring boot tries to connect to mysql database, both of which is running in minikube local machine. The application and database configuration should be alright, because it is working in local machine with localhost url.

The pod is able to reach the database pod with curl in shell, but the jdbc is not able to find database.

the jdbc error message:
Caused by: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

# curl -v $DB_HOST
*   Trying 10.109.201.118:3306...
* Connected to mysql-svc (10.109.201.118) port 3306 (#0)
> GET / HTTP/1.1
> Host: mysql-svc:3306
> User-Agent: curl/7.81.0
> Accept: */*
> 
* Received HTTP/0.9 when not allowed
* Closing connection 0
curl: (1) Received HTTP/0.9 when not allowed

application.yaml
---
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://${DB_HOST}/${DB_NAME}?useSSL=false
    username: ${DB_USERNAME}
    password: ${DB_PASSWORD}
    hikari:
      initialization-fail-timeout: 0
  jpa:
    database-platform: org.hibernate.dialect.MySQLDialect
    generate-ddl: true
    show-sql: true
    hibernate:
      ddl-auto: update

db-deploy.yaml
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv-volume # name of PV essential for identifying the storage data
  labels:
    app: mysql
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce   #This specifies the mode of the claim that we are trying to create.
  hostPath:
    path: "/var/lib/mysql"

---
# Define a 'Persistent Volume Claim'(PVC) for Mysql Storage, dynamically provisioned by cluster
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim # name of PVC essential for identifying the storage data
  labels:
    app: mysql
    tier: database
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce   #This specifies the mode of the claim that we are trying to create.
  resources:
    requests:
      storage: 5Gi    #This will tell kubernetes about the amount of space we are trying to claim.
---
# Configure 'Deployment' of mysql server
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-deploy
  labels:
    app: mysql
    tier: database
spec:
  selector: # mysql Pod Should contain same labels
    matchLabels:
      app: mysql
      tier: database
  strategy:
    type: Recreate
  template:
    metadata:
      labels: # Must match 'Service' and 'Deployment' selectors
        app: mysql
        tier: database
    spec:
      containers:
        - image: mysql:8.4 # image from docker-hub
#          args:
#            - "--ignore-db-dir=lost+found" # Workaround for https://github.com/docker-library/mysql/issues/186
          name: mysql
          env:
            - name: MYSQL_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-secret
                  key: password

          ports:
            - containerPort: 3306
              name: mysql
          volumeMounts:        # Mounting volume obtained from Persistent Volume Claim
            - name: mysql-persistent-storage
              mountPath: /var/lib/mysql #This is the path in the container on which the mounting will take place.
      volumes:
        - name: mysql-persistent-storage # Obtaining 'volume' from PVC
          persistentVolumeClaim:
            claimName: mysql-pv-claim
---
# Define a 'Service' To Expose mysql to Other Services
apiVersion: v1
kind: Service
metadata:
  name: mysql-svc  # DNS name
  labels: # mysql Pod Should contain same labels
    app: mysql
    tier: database
spec:
  ports:
    - protocol: TCP
      port: 3306
      targetPort: 3306
  selector:
    app: mysql
    tier: database
  clusterIP: None  # We Use DNS, Thus ClusterIP is not relevant
#  type: NodePort
#  type: ExternalName
#  externalName: my.database.host

app-deploy.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: onlineshopping-deploy
  labels:
    app: onlineshopping
spec:
  selector:
    matchLabels:
      app: onlineshopping
  replicas: 3
  template:
    metadata:
      labels:
        app: onlineshopping
    spec:
      containers:
        - name: onlineshopping-container
          image: tank73/onlineshopping:h1.0  # amazon/onlineshopping:1.0
          ports:
            - containerPort: 9000
          env:   # Setting Enviornmental Variables
            - name: DB_HOST   # Setting Database host address from configMap
              value : mysql-svc:3306
#              value : my.database.host:3306
            - name: DB_NAME  # Setting Database name from configMap
              value : onlineshopping
            - name: DB_USERNAME  # Setting Database username from Secret
              value : root
            - name: DB_PASSWORD # Setting Database password from Secret
              valueFrom:
                secretKeyRef:
                  name: mysql-secret
                  key: password

---
apiVersion: v1 # Kubernetes API version
kind: Service # Kubernetes resource kind we are creating
metadata: # Metadata of the resource kind we are creating
  name: onlineshopping-svc
spec:
  selector:
    app: onlineshopping
  ports:
    - protocol: TCP
      port: 9000 # The port that the service is running on in the cluster
      targetPort: 9000 # The port exposed by the service
  type: LoadBalancer # type of the service.

This is the link of my repository, you are welcome to take a look at my code and provide any suggestions.
https://github.com/Alex-Lin5/Amazon-Spring-Application