[FIXED] Problem with dockercompose connection to MySQL container

Issue

I'm having trouble connecting my spring application with the MySQL database. In particular, I report the code of the docker compose, the docker file, application.yml and the error log.

docker-compose:

version: '3.3'
services:
  my-sql-db:
    image: mysql:latest
 
    environment:
      - MYSQL_ROOT_PASSWORD=user
      - MYSQL_USER=user
      - MYSQL_DATABASE=spring-app
    ports:
      - "3306:3306"

  customerservice:

    image: customer-service
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "8080:8080"

    depends_on:
      - my-sql-db
    environment:
      SPRING_PROFILES_ACTIVE: MySQLdocker

Dockerfile:

FROM maven:3.6.3-jdk-8

COPY ./ ./

RUN mvn clean package

EXPOSE 8080

CMD ["java", "-jar", "target/my-spring-project-0.0.1-SNAPSHOT.jar"]

Application.yml:

spring:
  jpa:
    open-in-view: false #per levare warnig OpenSessionInView
    properties:
      hibernate:
        jdbc:
          time_zone: CET
        dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    hibernate:
      ddl-auto: none
  datasource:
    url: jdbc:mysql://my-sql-db:3306/spring-app?createDatabaseIfNotExist=true
    username: user
    password: user
  config:
    activate:
      on-profile: MySQLdocker

Executing the command "docker-compose up -d" the output error is:

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.27.jar!/:8.0.27] at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.27.jar!/:8.0.27]

Solution

I'm not seeing MYSQL_PASSWORD defined in your docker-compose file. Generally, the error suggests the app cannot connect to MySQL at all. When you have such a problem that could be caused by many things, you should try and narrow it down. Check if the DB is up and running. If yes, then try to connect to it from some MySQL client. And so on, until you figure out what exactly went wrong or at least come up with a more specific question.

Answered By - at54321