Dockerizing a Maven Java 11 Application

Introduction

Docker is a popular platform for containerizing applications. It allows developers to package their applications and their dependencies into a single container, which can then be run on any system that has Docker installed. In this article, I will guide you through the process of Dockerizing a Maven Java 11 application.

Prerequisites

Before we begin, make sure you have the following installed on your system:

  • Docker: You can download and install Docker from the official Docker website.

Process Overview

Below is a step-by-step process for Dockerizing a Maven Java 11 application:

journey
    title Dockerizing a Maven Java 11 Application
    section Clone the Maven Java 11 Application
    section Create a Dockerfile
    section Build the Docker Image
    section Run the Docker Container

Now, let's go through each step in detail.

Step 1: Clone the Maven Java 11 Application

First, you need to clone the Maven Java 11 application that you want to Dockerize. Use the following command to clone the repository:

git clone <repository-url>

Replace <repository-url> with the URL of the Git repository.

Step 2: Create a Dockerfile

Once you have cloned the application, navigate to the root directory of the project. Create a file named Dockerfile in the project's root directory. The Dockerfile is used to define the instructions for building the Docker image.

Open the Dockerfile in a text editor and add the following code:

# Use the official Maven 3.6.3 image as the base image
FROM maven:3.6.3-openjdk-11-slim

# Set the working directory in the container
WORKDIR /app

# Copy the pom.xml and src directory to the working directory
COPY pom.xml .
COPY src ./src

# Build the Maven project
RUN mvn package

# Set the entry point for the container
ENTRYPOINT ["java", "-jar", "target/your-application.jar"]

Let's understand the code in the Dockerfile:

  • FROM maven:3.6.3-openjdk-11-slim: This line specifies the base image to use for the Docker image. In this case, we are using the official Maven 3.6.3 image with OpenJDK 11.
  • WORKDIR /app: This line sets the working directory in the container to /app.
  • COPY pom.xml .: This line copies the pom.xml file from the local directory to the working directory in the container.
  • COPY src ./src: This line copies the entire src directory from the local directory to the working directory in the container.
  • RUN mvn package: This line builds the Maven project inside the container.
  • ENTRYPOINT ["java", "-jar", "target/your-application.jar"]: This line specifies the entry point command for the container. It runs the Java application using the your-application.jar file located in the target directory.

Save the Dockerfile and close the text editor.

Step 3: Build the Docker Image

Now that we have created the Dockerfile, we can build the Docker image using the following command:

docker build -t your-image-name .

Replace your-image-name with the desired name for the Docker image.

The docker build command reads the instructions from the Dockerfile and builds the Docker image accordingly. The -t option is used to tag the image with the given name.

Step 4: Run the Docker Container

Once the Docker image is built, we can run a Docker container using the following command:

docker run -d -p 8080:8080 your-image-name

Replace your-image-name with the name of the Docker image you built in the previous step.

The docker run command creates and starts a new Docker container based on the specified image. The -d option runs the container in detached mode, and the -p option maps the container's port 8080 to the host's port 8080.

Congratulations! You have successfully Dockerized a Maven Java 11 application. You can now access your application by navigating to http://localhost:8080 in your web browser.

Conclusion

Docker provides an efficient way to package and distribute applications with their dependencies. In this article, we learned how to Dockerize a Maven Java 11 application using a step-by-step process. By following these steps, you can easily containerize your own Java applications and deploy them in any environment that supports Docker.