Project Template: Create a Docker image for a Java application

A template project to create a Docker image for a Java application. The example application exposes an HTTP endpoint.

Golang developer? Check out https://github.com/miguno/golang-docker-build-tutorial

Features:

• The Docker build uses a multi-stage build setup to minimize the size of the generated Docker image, which is 176MB
• Supports Docker BuildKit
• Java 17 (Eclipse Temurin)
• Junit 5 for demonstrating how to integrate unit testing
• Maven for build management

Requirements

Docker must be installed on your local machine. That's it. You do not need a Java JDK or Maven installed.

Usage and Demo

Step 1: Create the Docker image according to Dockerfile. This step uses Maven to build, test, and package the Java application according to pom.xml. The resulting image is 176MB in size, of which 170MB are the underlying eclipse-temurin image.

# ***Creating an image may take a few minutes!***
$ docker build --platform linux/x86_64/v8 -t miguno/java-docker-build-tutorial:latest .

# You can also build with the new BuildKit.
# https://docs.docker.com/build/
$ docker buildx build --platform linux/x86_64/v8 -t miguno/java-docker-build-tutorial:latest .

Optionally, you can check the size of the generated Docker image:

$ docker images miguno/java-docker-build-tutorial
REPOSITORY                          TAG       IMAGE ID       CREATED         SIZE
miguno/java-docker-build-tutorial   latest    1403a608d055   4 minutes ago   176MB

Step 2: Start a container for the Docker image.

$ docker run -p 8123:8123 miguno/java-docker-build-tutorial:latest

Step 3: Open another terminal and access the example API endpoint of the running container.

$ curl http://localhost:8123/status
{"status": "idle"}

Notes

You can also build, test, package, and run the Java application locally (without Docker) if you have JDK 17+ and Maven installed.

# Build, test, package the application locally
$ mvn clean package

# Run the example application locally
$ java -jar target/app.jar