docker application not communicate with docker mysql container - spring-boot

Question

I just encountered a problem. I am dockerizing a springboot application with MySQL as a database it is perfectly working in a local setup. But when I try to dockerize the application using docker-compose, MySQL container is working fine and is accessible in my workbench but my application is not able to access it throwing the communication link failure.
This is the compose file I am using:
version: "3.8"
services:
mysqldb:
image: mysql:5.7
restart:unless-stopped
environment:
- MYSQL_ROOT_PASSWORD=root
- MYSQL_DATABASE=baskartest
ports:
- 3307:3306
volumes:
- db:/var/lib/mysql
app:
depends_on:
- mysqldb
build: ./bezkoder-app
restart:on-failure
env_file: ./.env
ports:
- 8084:8080
environment:
SPRING_APPLICATION_JSON: '{
"spring.datasource.url" : "jdbc:mysql://mysqldb:3306/baskartest?useSSL=false",
"spring.datasource.username" : "root",
"spring.datasource.password" : "root",
"spring.jpa.properties.hibernate.dialect" : "org.hibernate.dialect.MySQL5InnoDBDialect",
"spring.jpa.hibernate.ddl-auto" : "update"
}'
volumes:
- .m2:/root/.m2
stdin_open: true
tty: true
MySQL is working fine but my app in services is not able to communicate with it.
Here is what I see:
Any help would be appreciated!

Answer 1

I have done small changes in docker-compose.yml file, please use this one. It is working fine.
version: "3.8"
services:
mysqldb:
image: mysql:5.7
container_name: MYSQL_DB
restart: unless-stopped
environment:
- MYSQL_ROOT_PASSWORD=root
- MYSQL_DATABASE=baskartest
ports:
- 3307:3306
app:
build: ./bezkoder-app
restart: on-failure
ports:
- 8084:8080
environment:
- SPRING_DATASOURCE_URL=jdbc:mysql://MYSQL_DB:3306/baskartest
- SPRING_DATASOURCE_USERNAME=root
- SPRING_DATASOURCE_PASSWORD=root
- SPRING_JPA_HIBERNATE_DDL_AUTO=update
depends_on:
- mysqldb

Answer 2

In my short experience with Docker and containers communicating with eachother, I've found that localhost configuration URL's aren't working. Because one container can't communicatie with another container using just localhost:[PORT].
A lazy way for me to fix this is to work out a static IP address of the machine the containers are running on. Then use this (local) IP address instead of localhost to define the endpoint of the database.
In my situation with Redis I'm doing it like this:
return new LettuceConnectionFactory(new RedisStandaloneConfiguration("192.168.1.201", 6379));
In your situation, you might want to use a Datasource URL like this:
- SPRING_DATASOURCE_URL=jdbc:mysql://[STATIC_IP_OF_MACHINE]:3306/baskartest
*i.e. ...192.168.1.100:3306/baskartest...*