Spring Boot Docker Integration

Spring Boot provides multiple ways to containerize applications efficiently using Docker, Buildpacks, and Jib. This guide explores different approaches to building and deploying Spring Boot applications with Docker.

🌟 Why Use Docker for Spring Boot?

Portable Deployment: Run applications consistently across environments.
Scalability: Easily scale and manage containerized applications.
Lightweight and Efficient: Optimize resource utilization with minimal overhead.
DevOps Friendly: Seamlessly integrate with CI/CD pipelines.

🌟 Prerequisites

Ensure you have the following:

☕ Java Development Kit (JDK) 17+
📦 Maven or Gradle installed
🐳 Docker installed and running

🛠️ Step 1: Add Dependencies

To enable Docker support, add the Spring Boot Maven Plugin, Jib Plugin, and Spring Boot Web Starter to your build tool.

Maven Configuration:

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

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <groupId>com.google.cloud.tools</groupId>
            <artifactId>jib-maven-plugin</artifactId>
            <version>3.3.2</version>
        </plugin>
    </plugins>
</build>

Gradle Configuration:

plugins {
    id 'org.springframework.boot' version '3.2.0'
    id 'com.google.cloud.tools.jib' version '3.3.2'
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
}

To enable Docker support, add the Spring Boot Maven Plugin and Jib Plugin to your build tool.

Maven Configuration:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <groupId>com.google.cloud.tools</groupId>
            <artifactId>jib-maven-plugin</artifactId>
            <version>3.3.2</version>
        </plugin>
    </plugins>
</build>

Gradle Configuration:

plugins {
    id 'org.springframework.boot' version '3.2.0'
    id 'com.google.cloud.tools.jib' version '3.3.2'
}

📖 Step 2: Create a Simple Spring Boot Application

Define a REST endpoint to deploy inside a Docker container.

package com.example.docker;

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

@SpringBootApplication
@RestController
public class DockerApplication {

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

    @GetMapping("/hello")
    public String hello() {
        return "Hello from Spring Boot running in Docker!";
    }
}

package com.example.docker

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController

@SpringBootApplication
@RestController
class DockerApplication {

    @GetMapping("/hello")
    fun hello(): String = "Hello from Spring Boot running in Docker!"
}

fun main(args: Array<String>) {
    runApplication<DockerApplication>(*args)
}

🐳 Step 3: Build and Run a Docker Image

Option 1: Using Buildpacks

Spring Boot provides built-in support for creating Docker images without a Dockerfile using Buildpacks.

mvn spring-boot:build-image

gradle bootBuildImage

Run the container:

docker run --rm -p 8080:8080 myproject:0.0.1-SNAPSHOT

Option 2: Using Jib

Jib allows building optimized container images without a Docker daemon.

mvn jib:dockerBuild

gradle jibDockerBuild

Run the Jib-built container:

docker run --rm -p 8080:8080 myproject:0.0.1-SNAPSHOT

▶️ Running the Application

Once the container is running, test the REST API:

curl -X GET http://localhost:8080/hello

Expected Output:

Hello from Spring Boot running in Docker!

Spring Boot provides multiple approaches to containerizing applications efficiently. Whether you use Buildpacks for simplicity or Jib for optimized image builds, Dockerizing Spring Boot applications is seamless and production-ready.