Docker, Springboot and Mysql : com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

Question

I try to run a Springboot app with mysql connection on Docker. Without docker, it works well. But when I try to deploy on a container, I have com.mysql.cj.exceptions.CJCom

Answer 1

there is a difference between networks and links. use links like the one below

version: '2'
services:
    web:
        build: . 
        links: 
            - "db:database"
    db:
        image: postgres

this switch will add ID and IP address of one docker container in another on. in this way they can connect to each other. for more info check following link.

Answer 2

As your Spring Boot application is also launched in a docker image, you can't used the port exposed by docker, but instead you need to use the original port of the image.

In application.properties you need to use:

spring.datasource.url = jdbc:mysql://mysql:3306/db