Spring Boot cannot connect to MySQLand exits in Docker/Docker compose

Question

Below is my application.properties file

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://loca         


        

Answer 1

Containers in compose services can connect to other containers by using name, e.g. try to ping database container from spring-boot container.

Check if you can ping database container

docker-compose exec spring-boot-jpa-docker-webapp /bin/bash

once you are in the shell (You may have to install ping in spring-boot container for testing only apt-get install iputils-ping or yum install depending on image container is based on)

ping docker-mysql

if ping is successful then it means you can connect to database

replace database url in application.properties with

spring.datasource.url=jdbc:mysql://docker-mysql:3306/test?autoReconnect=true

Minimal Example for Mysql

image: mysql:latest
command: --default-authentication-plugin=mysql_native_password
restart: always
environment:
  MYSQL_ROOT_PASSWORD: root
volumes:
  - "./volumes/database:/var/lib/mysql"

Try following docker-compose

version: "3.7"
services:
  docker-mysql:
    image: mysql:latest
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    ports:
      - "3306:3306"
    environment:
      - MYSQL_ROOT_PASSWORD=root
      - MYSQL_DATABASE=test
    volumes:
      - "./volumes/database:/var/lib/mysql"
    networks:
      - spring_net
  spring-boot-jpa-docker-webapp:
    image: springboot_docker
    ports:
      - "8080:8080"
    networks:
      - spring_net
networks:
  spring_net:

Answer 2

You are passing the DATABASE_HOST, DATABASE_PORT, DATABASE_NAME, DATABASE_USER and DATABASE_PASSWORD but you are not using it inside your app.

Update your properties like this. (Better if your create a profile so that you app runs outside of docker)

spring.datasource.url=jdbc:mysql://${DATABASE_HOST}:${DATABASE_PORT}/${DATABASE_NAME}?autoReconnect=true
spring.datasource.username=${DATABASE_USER}
spring.datasource.password=${DATABASE_PASSWORD}

---

If you really want to use localhost as your db_url. You can also use network_mode: "service:[service name]" property of docker compose. Only downside is that this property cannot be used with port property.

version: '3'

services: 
  docker-mysql:
    image: mysql:latest
    network_mode: "service:spring-boot-jpa-docker-webapp"
    environment:
      - MYSQL_ROOT_PASSWORD=root
      - MYSQL_DATABASE=test
      - MYSQL_PASSWORD=root
  spring-boot-jpa-docker-webapp:
    image: springboot_docker
    depends_on:
      - docker-mysql
    ports:
      - 8080:8080
      - 3306 #Add this only if you want to expose the mysql to outer world.
    environment:
      - DATABASE_USER=root
      - DATABASE_PASSWORD=root
      - DATABASE_NAME=test

And your properties file could look like

spring.datasource.url=jdbc:mysql://localhost:3306/${DATABASE_NAME}?autoReconnect=true
spring.datasource.username=${DATABASE_USER}
spring.datasource.password=${DATABASE_PASSWORD}