Docker Intro

This project demonstrates a sample Docker container build and run configuration for a Spring Boot REST application. Using OpenJDK 17, Maven, and a custom Dockerfile, it serves as an example for containerizing Java applications.
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Notes

For additional insights on the Docker configurations and more, please refer to the following handwritten notes:
Handwritten Docker & Azure VM Setup Note
Handwritten LoadBalancing and Kubernetes Intro Note

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Table of Contents

1. About The Project
• Core Features
• Built With
2. Getting Started
• Prerequisites
• Installation and Setup
• Docker Usage
3. Project Structure
4. Documentation
5. Contributing
6. License
7. Contact

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About The Project

Docker Intro Sample Project is a demonstration of containerizing a Spring Boot REST application using Docker. The project includes:

• A Dockerfile that builds an image based on OpenJDK 17.
• A sample Spring Boot REST controller that exposes a simple endpoint.
• Maven build configurations where the final JAR name is customized using <finalName>Hello</finalName> in the pom.xml.

This project is designed to help developers quickly learn how to build, package, and run Docker containers for Java applications in a professional and scalable manner.

Core Features

• Containerization with Docker
  Utilizes a Dockerfile to package the application into a lightweight container.

• Spring Boot REST Controller
  Provides a sample endpoint to verify Docker container functionality:

  @RestController
  public class DockerTestController {
      @GetMapping("/docker")
      public String getDocker() {
          return "Docker Test Successful!";
      }
  }

• Maven Build Process
  Demonstrates a Maven-based build process with custom JAR naming for consistency in deployments.

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Built With

• Java 17 – Utilized via the OpenJDK 17 base image.
• Spring Boot – Framework for building the REST controller.
• Maven – Build and dependency management tool.
• Docker – Containerization platform.

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Getting Started

Follow these instructions to set up and run the Docker Intro Sample Project on your local machine.

Prerequisites

• Java JDK 17 or later.
• Maven (ensure you have Maven installed and configured).
• Docker – Installed and running on your system.
• IntelliJ IDEA (or your preferred IDE).

Installation and Setup

1. Clone the repository:

   git clone https://github.com/GRB-Workspace/Docker-Intro.git
   cd Docker-Intro

2. Open the project in IntelliJ IDEA.

3. Clean and Package the Project:

   Open your terminal in the project root and run:

   mvn clean
   mvn package

   This will clean your project and package your Spring Boot application into a JAR file (named Hello.jar as defined in your pom.xml).

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Docker Usage

The project includes a Dockerfile with the following configuration:

# Use OpenJDK 17 as base image
FROM openjdk:17-jdk-slim

# Add application JAR file to the container
ADD target/Hello.jar app.jar

# Expose the port that the application will run on
EXPOSE 8080

# Run the application
ENTRYPOINT ["java", "-jar", "app.jar"]

Building and Running the Docker Image

1. Build the Docker image:

   docker build -t docker-intro .

2. Run the Docker container:

   docker run -p 8080:8080 docker-intro

3. Test the application:

   Open your web browser or use cURL/Postman to access the endpoint:

   http://localhost:8080/docker
   

   You should receive the following response:

   Docker Test Successful!
   

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Project Structure

Docker-Intro/
├── src/
│   └── main/
│       ├── java/
│       │   └── me.grbulegoda.dockerintro/
│       │       └── DockerTestController.java
│       └── resources/
│           └── application.properties
├── target/
│   └── Hello.jar
├── Dockerfile
├── pom.xml
└── README.md

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Documentation

For an in-depth explanation of the Docker configurations and best practices, please refer to my detailed guide on Medium:

• Mastering Docker: A Professional Guide to Scalable Containerization

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Contributing

Contributions are welcome! If you have suggestions for improvements, bug fixes, or new features, please fork the repository and create a pull request. For any issues, feel free to open an issue on GitHub.

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License

Distributed under the MIT License. See the LICENSE file for details.

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Contact

Gayanuka Bulegoda
Portfolio • GitHub

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© 2025 Gayanuka Bulegoda

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