Running a Java App With MySQL in Any Docker Environment

We very often use a container for the deployment of a microservices application/java app. Using containers has various advantages, and Docker is one of the first choices to implement containerization. But for a beginner, using Docker with proper configuration is a tedious job, particularly if we use using a database as backends. Since containerization means isolation of any application to the external world, an application cannot access any of the services, which are running in a container. 

An application needs any kind of backend service. So the backend needs to expose to the external world. But, exposing the port of the database for the external world, is not a good idea. But this problem can be solved by connecting the container through Docker networking. By connecting the database with the java application through the docker network is the best option. This way, we can solve the portability issues in different environments like Dev, QA, and Prod.

A Spring Boot application running with MySQL in Docker container with Docker network.

application.properties for Springboot application, where MySQL is running in Docker container in a network with name app_network.

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# configure mysql database

spring.jpa.hibernate.ddl-auto=update

spring.datasource.url=jdbc:mysql://mysql_name:3306/database_name

spring.datasource.username=root

spring.datasource.password=password

The Spring Boot application can communicate to MySQL in Docker containers, through the docker network.

The name of Docker network is app_network:

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docker network create app_network

Dockerfile file for Spring Boot is configured as follows.

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FROM openjdk:14

CMD [“mkdir”, “app”]

WORKDIR app/

COPY target/sampleApp.jar app/app.jar

EXPOSE 8082

CMD [“java”, “-jar”, “app/app.jar”]

Spring Boot application image name is sample_app.

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docker build -t sample_app .

Running Spring Boot image in Docker with network app_network

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docker run -d -it -p 8082:8080 --network app_network --name sample_app sample_app

MySQL is running in Docker as mysql_name with password "password" and database "database_name" as follows:

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docker run -d -it --network app_network -e MYSQL_ROOT_PASSWORD=password -e MYSQL_DATABASE=database_name --name mysql_name mysql

Now Spring Boot application can be run in any Docker environment without any IP address conflict.