1. Introduction

In this tutorial, we’ll generate a Docker image of Spring Boot application with Google Jib.

2. What is Google Jib?

Google Jib is an open-source Java containerization tool that allows developers to build Docker and OCI (Open Container Initiative) images for Java applications without needing a Docker daemon or writing a Dockerfile. Jib integrates directly with popular Java build tools like Maven and Gradle, simplifying the process of creating container images.

2.1 Key feature of Google Jib

• No Docker Required: You don’t need Docker installed to use Jib. It builds images directly using Java build tools.
• Faster Builds: Jib optimizes the build process by layering application files intelligently, which helps reduce image size and speeds up subsequent builds.
• Integrated with Maven and Gradle: Easily configure Jib within your pom.xml (Maven) or build.gradle (Gradle) files.
• Customizable: You can specify the base image, JVM flags, and entry points for the application.
• Push to Registries: Jib supports pushing images directly to container registries like Docker Hub, Google Container Registry, and others.

3. jib-maven-plugin

In this tutorial, we’ll use the jib-maven-plugin to create Docker image.

To setup Jib, add the following plugin in your pom.xml.

			<plugin>
				<groupId>com.google.cloud.tools</groupId>
				<artifactId>jib-maven-plugin</artifactId>
				<version>3.3.2</version>
				<configuration>
					<to>
						<image>demoimage</image>
					</to>
				</configuration>
			</plugin>

Following is the complete 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>3.3.5</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.learnitweb</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo</name>
	<description>Demo project for Spring Boot</description>
	<url />
	<licenses>
		<license />
	</licenses>
	<developers>
		<developer />
	</developers>
	<scm>
		<connection />
		<developerConnection />
		<tag />
		<url />
	</scm>
	<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>
			<plugin>
				<groupId>com.google.cloud.tools</groupId>
				<artifactId>jib-maven-plugin</artifactId>
				<version>3.3.2</version>
				<configuration>
					<to>
						<image>demoimage</image>
					</to>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

We’ll create a HelloController to test our application:

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

@RestController
@RequestMapping("/api")
public class HelloController {

	@GetMapping("/hello")
	public String sayHello() {
		return "Hello, World!";
	}
}

4. Building image

Jib can also build your image directly to a Docker daemon. This uses the docker command line tool and requires that you have docker available on your PATH.

mvn compile jib:dockerBuild

5. Run the Docker image

Once the image is ready, you can run the image.

docker run -p 8081:8080 demoimage