application springboot does not connect with mysql in the Docker environment

Question

I’m starting in the container world, and when trying to upload an application developed in Springboot with mysql integration in Docker in an aws ec2, the application does not connect to mysql.

Mistakes:

...
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
...
Caused by: java.net.UnknownHostException: mysql_server

Docker-Compose.yaml:

version: '3.8'

networks:
  api-network:
    driver: bridge

volumes:
  mysql-vol:

services:
  mysql_server:
    image: mysql:5.6
    volumes: 
      - mysql-vol:/var/lib/mysql
    ports:
      - "3306:3306"
    environment:
      - MYSQL_DATABASE=ecommerce
      - MYSQL_USER=root
      - MYSQL_ALLOW_EMPTY_PASSWORD=yes
    networks:
      - api-network

  api_ecommerce:
    build:
    context: .
    dockerfile: Dockerfile
    ports:
      - "8080:8080"
    networks:
      - api-network
    depends_on:
      - mysql_server

application properties:

server.port=8080
spring.datasource.url=jdbc:mysql://mysql_server:3306/ecommerce
spring.datasource.username=root
spring.datasource.password=
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

mysql in pom.xml:

   <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>

Answer 1

No depends_on api_commerce, put like this:

depends_on:
      mysql_server:
        condition: service_healthy

In mysql_server, put:

       healthcheck:
            test: ["CMD", "mysqladmin" ,"ping", "-h", "localhost"]
            timeout: 20s
            retries: 10

That way, you’re saying: api_commerce depends on service_healthy return ok from mysql_server.

The okay mysql_server will come from that healthcheck that responds positively if the service has already gone up.

_{If it goes wrong comment that I play on my machine until I get the solution.}