Docker compose service not connecting to mysql container-CodePudding

I am trying to connect my service to MySQL docker container via docker-compose. The connection is refused. I tried to run MySQL docker image and connect my running service to it locally. the connection is established and everything is working fine. The problem is when I want to run both the service and MySQL container, the connection is refused. I created the custom network and tried many solutions but it has already taken me 2 days!

the docker compose configs are:

    version : '3.8'
services:
  healthcare:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "8080:8080"
    depends_on:
      - mysql
    restart: always
    environment:
      RDS_URL: mysql
    networks:
      - saman-network
    
  mysql:
    image: mysql:8-oracle
    container_name:
      mysql
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: hospital_db
      MYSQL_USER: saman
      MYSQL_PASSWORD: saman
    volumes:
      - myvolume:/var/lib/mysql
    ports:
      - "3308:3306"
    networks:
      - saman-network
volumes:
  myvolume:
  
networks:
  saman-network:

the application.properties configs are:

server.port=8080
spring.application.name=healthcare
spring.datasource.url=jdbc:mysql://${RDS_URL:localhost}:3308/hospital_db
spring.datasource.username=saman
spring.datasource.password=saman
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQLDialect
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=update
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

the error I am getting:

springboot-hospitalmng-sample-healthcare-1  |   ... 46 common frames omitted
springboot-hospitalmng-sample-healthcare-1  | Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

and

 springboot-hospitalmng-sample-healthcare-1  |   ... 59 common frames omitted
springboot-hospitalmng-sample-healthcare-1  | Caused by: java.net.ConnectException: Connection refused
springboot-hospitalmng-sample-healthcare-1  |   at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
springboot-hospitalmng-sample-healthcare-1  |   at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[na:na]
springboot-hospitalmng-sample-healthcare-1  |   at java.base/sun.nio.ch.NioSocketImpl.timedFinishConnect(NioSocketImpl.java:542) ~[na:an]


springboot-hospitalmng-sample-healthcare-1  | The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
springboot-hospitalmng-sample-healthcare-1  | 2023-01-05T14:20:37.165Z ERROR 1 --- [           main] j.LocalContainerEntityManagerFactoryBean : Failed to initialize JPA EntityManagerFactory: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to open JDBC Connection for DDL execution

CodePudding user response：

I think this is the problem. mysql runs on port 3306, you expose it on the host on 3308. But from the configuration you connect through the docker network using RDS_URL but port 3308, it should be 3306 instead