Spring Boot + MySQL + Docker Compose - Cannot make Spring Boot connect to MySQL - mysql

Question

I've been trying to set up a connection between a backend (runs on Spring Boot) container and a pre-built MySQL container. However, I cannot get it to connect. My docker compose file is:
version: '3.7'
services:
test-mysql:
image: mysql
restart: always
volumes:
- db_data:/var/lib/mysql
environment:
MYSQL_DATABASE: testdb
MYSQL_USER: test
MYSQL_PASSWORD: test
MYSQL_ROOT_PASSWORD: root
backend:
depends_on:
- test-mysql
build:
context: backend
dockerfile: Dockerfile
ports:
- "8080:8080"
restart: always
volumes:
db_data: {}
my application.properties:
spring.jpa.hibernate.ddl-auto=update
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect
spring.datasource.url=jdbc:mysql://test-mysql:3306/testdb?autoReconnect=true&failOverReadOnly=false&maxReconnects=10
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=test
spring.datasource.password=test
When I use docker-compose up, Spring Boot is not able to recognize the container name test-mysql. It throws: java.net.UnknownHostException
When I change it to an IP, it says connection refused. I have been looking everywhere and couldn't come with a fix. I hope anyone can help me out. Thank you!

Answer 1

You have to mention the backend mysql properties in the composer file like below,
backend:
depends_on:
- test-mysql
build:
context: backend
dockerfile: Dockerfile
ports:
- "8080:8080"
restart: always
environment:
SPRING_DATASOURCE_URL: jdbc:mysql://test-
mysql:3306/testdbautoReconnect=true&failOverReadOnly=false&maxReconnects=10
SPRING_DATASOURCE_USERNAME: test
SPRING_DATASOURCE_PASSWORD: test
links:
- test-mysql:test-mysql
If this wouldn't work try to create a common docker network and add it to your composer file like below,
backend:
depends_on:
- test-mysql
build:
context: backend
dockerfile: Dockerfile
ports:
- "8080:8080"
restart: always
environment:
SPRING_DATASOURCE_URL: jdbc:mysql://test-
mysql:3306/testdbautoReconnect=true&failOverReadOnly=false&maxReconnects=10
SPRING_DATASOURCE_USERNAME: test
SPRING_DATASOURCE_PASSWORD: test
networks:
-common-network
test-mysql:
image: mysql
restart: always
volumes:
- db_data:/var/lib/mysql
environment:
MYSQL_DATABASE: testdb
MYSQL_USER: test
MYSQL_PASSWORD: test
MYSQL_ROOT_PASSWORD: root
networks:
-common-network
#Docker Networks
networks:
common-network:
driver: bridge
#Volumes
volumes:
dbdata:
driver: local

Answer 2

You can define a common network on which both the application server and the database can connect. Please check the file (docker-compose.yml) below where I have defined a common network: backend
# Docker Compose file Reference (https://docs.docker.com/compose/compose-file/)
version: '3.7'
# Define services
services:
# App backend service
app-server:
# Configuration for building the docker image for the backend service
build:
context: . # Use an image built from the specified dockerfile in the `springboot-app-server` directory.
dockerfile: Dockerfile
ports:
- "8080:8080" # Forward the exposed port 4000 on the container to port 4000 on the host machine
restart: always
depends_on:
- db # This service depends on mysql. Start that first.
environment: # Pass environment variables to the service
SPRING_DATASOURCE_URL: jdbc:mysql://test-mysql:3306/testdb?useSSL=false&serverTimezone=UTC&useLegacyDatetimeCode=false
SPRING_DATASOURCE_USERNAME: test
SPRING_DATASOURCE_PASSWORD: test
networks: # Networks to join (Services on the same network can communicate with each other using their name)
- backend
# Database Service (Mysql)
db:
image: mysql:5.7
ports:
- "3306:3306"
restart: always
environment:
MYSQL_DATABASE: testdb
MYSQL_USER: test
MYSQL_PASSWORD: test
MYSQL_ROOT_PASSWORD: root
volumes:
- db-data:/var/lib/mysql
networks:
- backend
# Volumes
volumes:
db-data:
# Networks to be created to facilitate communication between containers
networks:
backend:
I have written a blog and a simple working Spring Boot MySQL application on GitHub which tells about using Docker Compose. Please check: http://softwaredevelopercentral.blogspot.com/2020/10/spring-boot-mysql-docker-compose-example.html

Answer 3

If you would like to use this test-mysql in your spring config
spring.datasource.url=jdbc:mysql://test-mysql:3306/testdb?autoReconnect=true&failOverReadOnly=false&maxReconnects=10
Then add the hostname attribute at service test-mysql
version: '3.7'
services:
test-mysql:
image: mysql
hostname: test-mysql
...

Answer 4

I hope this has been already solved but in case it hasn't yet, the problem lies in mysql docker container lagging behind the start up.
Another problem is that you might need to build the jar file and then copy it the container. That's a big problem because when you build the jar file, the database with db as hostname is unavailable. So when you are building the jar file, skip the test.
This is bash script i created but you can run command one by one:
#!/bin/bash
cd storage-service
rm -rf target/
mvn clean compile package -Dmaven.test.skip=true
cd ..
docker-compose up
In case you want to initialize db in the container. That file is in the folder env where i have a file database.env
-- create the databases
CREATE DATABASE IF NOT EXISTS model_storage;
-- create the users for each database
CREATE USER 'arsene'#'localhost' IDENTIFIED BY 'arsene';
GRANT CREATE, ALTER, INDEX, LOCK TABLES, REFERENCES, UPDATE, DELETE, DROP, SELECT, INSERT ON `model_storage`.* TO 'arsene'#'localhost';
FLUSH PRIVILEGES;
The backend service Dockerfile looks like this:
FROM adoptopenjdk/openjdk11
COPY target/*.jar storage.jar
ENV JAVA_OPTS=""
ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar /storage.jar" ]
EXPOSE 8089
The database env file looks like this:
MYSQL_ROOT_PASSWORD=arsene
MYSQL_DATABASE=model_storage
MYSQL_USER=arsene
MYSQL_PASSWORD=arsene
DATABASE_HOST=model_storage
DATABASE_USER=arsene
DATABASE_PASSWORD=arsene
DATABASE_NAME=model_storage
DATABASE_PORT=3306
In case you intend to pass JAVA_OPTS env in the image. These can be used later as seen in docker-compose.yml below
Your backend (the service that depends on the mysql db) needs to restart until the docker-compose is able to resolve the the container name of mysql, in my case its name is db. And don't forget to include datasource connection properties in docker-compose backend service image as i did below. I am not an expert in spring boot and neither in docker but for now it works!
Below is the way mine is structured:
I am using docker version: "3.8"
Storage service
storage-service:
container_name: storage-service
restart: always
build:
context: storage-service
image: "service_storage_image"
depends_on:
- db
ports:
- "8089:8089"
links:
- db
env_file:
- env/database.env
environment:
WAIT_HOSTS: db:3306
SPRING_DATASOURCE_URL: jdbc:mysql://db:3306/model_storage?allowPublicKeyRetrieval=true&useSSL=false
SPRING_DATASOURCE_USERNAME: root
SPRING_DATASOURCE_PASSWORD: arsene
healthcheck:
test: "/usr/bin/mysql --user=arsene --password=arsene--execute \"SHOW DATABASES;\""
interval: 2s
timeout: 20s
retries: 10
environment:
- JAVA_OPTS=
-DEUREKA_SERVER=http://eureka-registry-server:7070/eureka
-DZIPKIN_SERVER=http://zipkin:9411/
networks:
- private-network-mms
My db in docker-compose is structured this way:
Mysql database
db:
hostname: db
container_name: db
image: "mysql:latest"
env_file:
- env/database.env
volumes:
- type: bind
source: ./env/setup.sql
target: /docker-entrypoint-initdb.d/setup.sql
- db_volume:/var/lib/mysql
ports:
- 3307:3306
networks:
- private-network-mms