Im trying to append a system environment in to a database connection string.

I got a kubernetes cluster running with minikube, where a pod is running with mysql image and has a service with ClusterIP, and another pod running my backend java application using a service with LoadBalancer.
I want to refer to the environment variable that is being made for the service by kubernetes, and im not sure if im doing it properly. When i refer to the environment variable SERVICENAME_SERVICE_HOST in my spring application, i get the ip address. However it seems to fail to set the jdbc url in my application.yaml . Im suspecting that i am not concatinating the environment variable properly as it worked fine when i used localhost instead of environment variable when both pods used LoadBalancer and shared the same service in kubernetes.

Please excuse me if the problem is poorly explained. il provide more files/snippets if required

My application.yaml file:

 spring:
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  datasource:
    url: "jdbc:mysql://${SQL_SERVICE_SERVICE_HOST}:3306/peopledb?createDatabaseIfNotExist=true"
    username: root
    password: "${MYSQL_ROOT_PASSWORD}"
    driver-class-name: com.mysql.cj.jdbc.Driver

deployment/service for kubernetes:

apiVersion: v1
kind: Service
metadata:
  name: backend-service
spec:
  selector:
    app: backend
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 8080
    name: backend
  type: LoadBalancer
---
apiVersion: v1
kind: Service
metadata:
  name: sql-service
spec:
  selector:
    app: mysql
  ports:
  - port: 3306
    targetPort: 3306
    name: mysql
  type: ClusterIP
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: backend-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: backend
  template:
    metadata:
      labels:
        app: backend
    spec:
      containers:
      - name: backend
        image: <imagelink redacted>
        ports:
        - containerPort: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:latest
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "mysecret"