Minikube Kubernetes, Postgres, Spring Boot Cluster - Postgres connection refused

so I have a basic minikube cluster configuration for K8s cluster with only 2 pods for Postgres DB and my Spring app. However, I can't get my app to connect to my DB. I know that in Docker such issue could be solved with networking but after a lot of research I can't seem to find the problem and the solution to my issue.

Currently, given my configuration I get a Connection refused error by postgres whenever my Spring App tries to start:

Caused by: org.postgresql.util.PSQLException: Connection to postgres-service:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

So my spring-app is a basic REST API with some open endpoints where I query for some data. The app works completely fine and here is my application.properties:

spring.datasource.driverClassName=org.postgresql.Driver
spring.datasource.url=jdbc:postgresql://${POSTGRES_HOST}:${POSTGRES_PORT}/${POSTGRES_DB}
spring.datasource.username=${POSTGRES_USER}
spring.datasource.password=${POSTGRES_PASSWORD}
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect
spring.jpa.hibernate.ddl-auto=update

The way I create my Postgres component is by creating a ConfigMap, a Secret and finally a Deployment with it's Service inside. They look like so:

postgres-config.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: postgres-config
data:
  postgres-url: postgres-service
  postgres-port: "5432"
  postgres-db: "test"

postgres-secret.yaml

apiVersion: v1
kind: Secret
metadata:
  name: postgres-secret
type: Opaque
data:
  postgres_user: cm9vdA== #already encoded in base64
  postgres_password: cm9vdA== #already encoded in base64

postgres.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres-deployment
  labels:
    app: postgres
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
        - name: postgresdb
          image: postgres
          ports:
            - containerPort: 5432
          env:
            - name: POSTGRES_USER
              valueFrom:
                secretKeyRef:
                  name: postgres-secret
                  key: postgres_user
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: postgres-secret
                  key: postgres_password
            - name: POSTGRES_DB
              valueFrom:
                configMapKeyRef:
                  name: postgres-config
                  key: postgres-db
---
apiVersion: v1
kind: Service
metadata:
  name: postgres-service
spec:
  selector:
    app.kubernetes.io/name: postgres
  ports:
    - protocol: TCP
      port: 5432
      targetPort: 5432

and finally here's my Deployment with it's Service for my spring app

spring-app.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: spring-app-deployment
  labels:
    app: spring-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: spring-app
  template:
    metadata:
      labels:
        app: spring-app
    spec:
      containers:
        - name: spring-app
          image: app #image is pulled from my docker hub
          ports:
            - containerPort: 8080
          env:
            - name: POSTGRES_USER
              valueFrom:
                secretKeyRef:
                  name: postgres-secret
                  key: postgres_user
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: postgres-secret
                  key: postgres_password
            - name: POSTGRES_HOST
              valueFrom:
                configMapKeyRef:
                  name: postgres-config
                  key: postgres-url
            - name: POSTGRES_PORT
              valueFrom:
                configMapKeyRef:
                  name: postgres-config
                  key: postgres-port
            - name: POSTGRES_DB
              valueFrom:
                configMapKeyRef:
                  name: postgres-config
                  key: postgres-db
---
apiVersion: v1
kind: Service
metadata:
  name: spring-app-service
spec:
  type: NodePort
  selector:
    app.kubernetes.io/name: spring-app
  ports:
    - protocol: TCP
      port: 8080
      targetPort: 8080
      nodePort: 30001