How to build a Java EE web app in a Docker container?

Introduction

In this tutorial, you will learn how to build a Java EE web application and deploy it in a Docker container. Docker is a popular containerization platform that allows you to package your application and its dependencies into a single, portable unit, making it easier to develop, test, and deploy your software. By the end of this guide, you'll have a better understanding of how to leverage Docker to streamline the development and deployment of your Java EE web applications.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL docker(("`Docker`")) -.-> docker/ContainerOperationsGroup(["`Container Operations`"]) docker(("`Docker`")) -.-> docker/ImageOperationsGroup(["`Image Operations`"]) docker(("`Docker`")) -.-> docker/DockerfileGroup(["`Dockerfile`"]) docker/ContainerOperationsGroup -.-> docker/create("`Create Container`") docker/ContainerOperationsGroup -.-> docker/ps("`List Running Containers`") docker/ContainerOperationsGroup -.-> docker/run("`Run a Container`") docker/ContainerOperationsGroup -.-> docker/start("`Start Container`") docker/ContainerOperationsGroup -.-> docker/stop("`Stop Container`") docker/ImageOperationsGroup -.-> docker/pull("`Pull Image from Repository`") docker/DockerfileGroup -.-> docker/build("`Build Image from Dockerfile`") docker/ContainerOperationsGroup -.-> docker/ls("`List Containers`") subgraph Lab Skills docker/create -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/ps -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/run -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/start -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/stop -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/pull -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/build -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} docker/ls -.-> lab-411507{{"`How to build a Java EE web app in a Docker container?`"}} end

Introduction to Docker and Java EE

What is Docker?

Docker is an open-source platform that allows developers to build, deploy, and run applications in containers. Containers are lightweight, standalone, and executable software packages that include everything needed to run an application, including the code, runtime, system tools, and libraries. Docker simplifies the process of creating, deploying, and managing applications by providing a consistent and reliable environment across different computing platforms.

What is Java EE?

Java EE (Java Enterprise Edition) is a collection of Java APIs and runtime environments for developing and running large-scale, enterprise-level applications. It provides a standard set of services, APIs, and protocols for building distributed, multi-tier Java applications. Java EE includes features such as web services, security, transaction management, and more, making it a popular choice for building enterprise-level web applications.

Advantages of Containerizing Java EE Applications with Docker

Containerizing Java EE applications with Docker offers several benefits:

Consistent Deployment: Docker containers ensure that the application and its dependencies are packaged together, providing a consistent and reliable environment across different computing platforms.
Scalability: Docker makes it easy to scale applications up or down based on demand, improving overall system performance and resource utilization.
Isolation: Containers provide a high degree of isolation, ensuring that one application's dependencies or configuration do not interfere with other applications running on the same host.
Portability: Docker containers can be easily moved between different environments (e.g., development, staging, production) without the need for complex configuration changes.
Efficiency: Docker containers are lightweight and use fewer resources compared to traditional virtual machines, making them more efficient for deploying and running applications.

Getting Started with Docker and Java EE

To get started with Docker and Java EE, you'll need to have Docker installed on your system. You can download and install Docker from the official Docker website (https://www.docker.com/get-started). Once you have Docker installed, you can start building and running your Java EE applications in Docker containers.

graph TD A[Java EE Application] --> B[Docker Container] B --> C[Docker Host] C --> D[Docker Engine] D --> E[Host Operating System]

In the next section, we'll dive deeper into the process of developing a Java EE web application and containerizing it using Docker.

Developing a Java EE Web App

Creating a Java EE Web Application

To develop a Java EE web application, you can use an Integrated Development Environment (IDE) such as IntelliJ IDEA, Eclipse, or NetBeans. These IDEs provide tools and frameworks to simplify the development process.

Here's an example of how you can create a simple Java EE web application using Jakarta EE (formerly known as Java EE):

Create a new project: In your IDE, create a new Maven or Gradle project and select the "Java EE" or "Jakarta EE" project template.
Add dependencies: In your project's pom.xml or build.gradle file, add the necessary dependencies for your Java EE web application, such as jakarta.servlet-api, jakarta.faces-api, and any other libraries you plan to use.
Develop the application logic: Create your Java classes, JSF (JavaServer Faces) or Servlet components, and other necessary files to implement the business logic of your web application.
Configure the web application: In your project, create a web.xml file (or use annotations) to configure the servlet, filters, and other web application settings.
Build and test the application: Use your IDE's build and run functions to compile, package, and test your Java EE web application locally.

graph TD A[Java EE Web Application] --> B[Jakarta EE API] B --> C[Servlet Container] C --> D[Application Server] D --> E[Host Operating System]

Deploying the Java EE Web Application

Once you have developed your Java EE web application, you can deploy it to an application server, such as Apache Tomcat, WildFly, or GlassFish. The deployment process typically involves the following steps:

Package the application: Use your IDE or a build tool (e.g., Maven, Gradle) to package your Java EE web application into a WAR (Web Application Archive) file.
Deploy the WAR file: Copy the WAR file to the deployment directory of your application server, or use the server's management console to deploy the application.
Start the application server: If the application server is not already running, start it to deploy and run your Java EE web application.

After deploying the application, you can access it through a web browser using the appropriate URL (e.g., http://localhost:8080/your-app).

Now that you have a basic understanding of developing a Java EE web application, let's move on to the next step: containerizing and deploying the application using Docker.

Containerizing and Deploying the Java EE App

Creating a Docker Image for the Java EE Web App

To containerize your Java EE web application using Docker, you'll need to create a Docker image. Here's an example of a Dockerfile that you can use:

## Use a base image with Java and an application server
FROM openjdk:11-jdk-slim as builder

## Copy the Java EE web application WAR file into the container
COPY target/*.war /app.war

## Use a lightweight application server image as the final image
FROM tomcat:9.0-jdk11-openjdk-slim

## Copy the WAR file into the Tomcat webapps directory
COPY --from=builder /app.war /usr/local/tomcat/webapps/

## Expose the default Tomcat port
EXPOSE 8080

## Start the Tomcat server
CMD ["catalina.sh", "run"]

In this example, we use a multi-stage build process. The first stage, builder, copies the Java EE web application WAR file into the container. The second stage, tomcat:9.0-jdk11-openjdk-slim, is a lightweight Tomcat image that serves as the final image. The WAR file is then copied into the Tomcat webapps directory, and the Tomcat server is started.

Building and Running the Docker Image

To build the Docker image, run the following command in the directory containing the Dockerfile:

docker build -t my-java-ee-app .

This will create a Docker image with the tag my-java-ee-app.

To run the Docker container, use the following command:

docker run -p 8080:8080 my-java-ee-app

This will start the Docker container and map the container's port 8080 to the host's port 8080, allowing you to access the Java EE web application from your web browser at http://localhost:8080.

Deploying the Java EE App to a Docker Swarm or Kubernetes

Once you have your Java EE web application containerized and running in a Docker container, you can deploy it to a Docker Swarm or Kubernetes cluster for scalability and high availability.

In a Docker Swarm, you can create a service using the docker service create command, specifying the Docker image and any necessary configuration options.

In a Kubernetes cluster, you can create a Deployment, Service, and other Kubernetes resources to manage the deployment and scaling of your Java EE web application.

graph TD A[Java EE Web App Docker Image] --> B[Docker Container] B --> C[Docker Swarm or Kubernetes] C --> D[Production Environment]

By containerizing your Java EE web application and deploying it to a container orchestration platform, you can take advantage of the benefits of Docker, such as consistent deployment, scalability, and portability, to ensure the reliable and efficient operation of your enterprise-level web application.

Summary

This tutorial has provided a comprehensive guide on how to build a Java EE web application and deploy it in a Docker container. By containerizing your Java EE app, you can benefit from improved portability, scalability, and consistency across different environments. Docker simplifies the deployment process and ensures that your application runs the same way, regardless of the underlying infrastructure. With the knowledge gained from this tutorial, you can now confidently use Docker to streamline the development and deployment of your Java EE web applications.