Dockerizing Spring Boot Application

This blog will help you in Dockerizing your Spring Boot application. A sample project is commited on Github using this tutorial. Click here to check the project.

Prerequisites:

• Docker must be installed on your machine.
• You have basic knowledge of Spring profiling.

1. Add DockerFile & Entrypoint in Your Project:

Create src/main/docker  in your project and add DockerFile in your project. This file is not a project-specific file; all you need to change is MAINTAINER  and LOG_PATH . We are using openjdk8-slim as the base image. For security, we are creating a separate user for the container.

Change your BOOTAPP_JAVA_OPTS according to your need.

• Add the entrypoint file wrapper.sh  in src/main/docker 

#!/usr/bin/env bash
exec java -Djava.security.egd=file:/dev/./urandom $BOOTAPP_JAVA_OPTS -jar  -Dspring.profiles.active=$ENV_NAME $BOOTAPP_PATH --server.port=$SERVER_PORT > /dev/stdout 2>&1

2. Update Your POM:

• Add the Docker registry in the properties section of your POM. This is where your Docker images will be pushed.

<docker.registry>javatechy</docker.registry>

• At first, add the docker-maven-plugin by Fabric8 to your project’s POM:

3. Build The Image:

To build the image do mvn clean install. This will build your Docker image and store it in your local Docker repository.

To check your image run docker images  .  

4. Push Your Image:

To Push your image use mvn docker:push . This will push your image to your remote container registry.

5. Play with Your Container:

To start your built container:

docker run -it -p 9000:8000 --name docker_boot_app -d javatechy/dockboot

This will start your container on port 9000 . 

Browse your application on http://localhost:9000/docker_boot/health

Check your container using docker ps -a 

In this blog, we learned how we can dockerize your spring boot application using docker-maven-plugin.