Dockerize Spring Boot App

In this tutorial, we will dockerize a spring boot application.

Build a simple microservice

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.1.2</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.jts</groupId>
	<artifactId>boot-with-docker</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>boot-with-docker</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>17</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

Controller class

package com.jts;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class SimpleController {
	
	@RequestMapping("/hello")
	public String hello() {
		return "Welcome to spring boot. Let's dockerize this application";
	}

}

Package the application

run as -> maven package or maven install

Now, go the project root folder and create a file Dockerfile there

Content of the Dockerfile is as below

FROM openjdk:18

WORKDIR /app

COPY ./target/boot-with-docker-0.0.1-SNAPSHOT.jar /app

EXPOSE 8080

CMD ["java", "-jar", "boot-with-docker-0.0.1-SNAPSHOT.jar"]

Create the docker image

Run the below command

docker build -t docker-boot-app:firstImage .

Create docker container by running below command

docker run -d -p 8080:8080 –name firstImage docker-boot-app:firstImage

You can verify on Docker Desktop that the container is running now

Test on the browser

Please note that this application is running on Docker. You can see that your local server is stopped, still you can access the url. This is because the app is running of the Docker.