Dockerizing a Spring Boot Application

• posted by Gastón Borba
• server
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Spring Boot with Docker

This guide walks you through the process of building a Docker image for running a Spring Boot application.

What You Will Need

• JDK 17
• Maven
• Docker

Starting with Spring Initializr

You can use this pre-initialized project and click Generate to download a ZIP file. This project is configured to fit the examples in this tutorial.

To manually initialize the project:

1. Navigate to https://start.spring.io.
2. Choose Maven and the language you want to use. This guide assumes that you chose Java.
3. Click Dependencies and select Spring Web.
4. Click Generate.

Set up a Spring Boot Application

Now you can update the DemoApplication.java:

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController
public class DemoApplication {

  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }

  @RequestMapping("/")
  public String home() {
    return "Hello World!";
  }
	
}

Containerize It

Create the following Dockerfile in your Spring Boot project:

FROM maven:3.8.5-openjdk-17 as build

WORKDIR /app

COPY pom.xml .
RUN mvn dependency:go-offline -DskipTests

COPY src src
RUN mvn clean package

FROM openjdk:17

COPY --from=build /app/target/*.jar app.jar

EXPOSE 8080
ENTRYPOINT ["java","-jar","/app.jar"]

Build the Docker Image

docker build -t demo:latest .

Run the Container

docker run -p 8080:8080 demo:latest

Now you can visit http://localhost:8080
You can download the source code here