How to Easily Deploy a Java War File to a Docker Container

Deploying a Java War in a Docker Container

Docker containers are becoming increasingly popular for deploying applications, due to the improved scalability and security they offer. A Java war (web archive) is a collection of files in a folder hierarchy that is bundled together as a single file for deployment. In this tutorial, we'll discuss how to deploy a Java war in a Docker container.

Prerequisites

• A working Docker installation.
• A Java war file.
• Access to the Docker command line.

Step 1: Create a Docker Image

The first step is to create a Docker image that will serve as the basis for the container. This image will contain the necessary components to run the web application, such as the web server and any supporting libraries. To do this, create a Dockerfile with the following contents:

FROM openjdk:8-jre-alpine

ARG WAR_FILE
ADD ${WAR_FILE} /app/app.war

EXPOSE 8080

CMD ["java", "-jar", "/app/app.war"]

This Dockerfile will create an image based on the OpenJDK 8 JRE. It will then copy the specified war file into the image and expose port 8080. Finally, it will set the default command for the container to run the web application.

Step 2: Build the Image

Once the Dockerfile has been created, it can be used to build an image. To do this, run the following command, substituting the path to the war file:

docker build -t myimage --build-arg WAR_FILE=path/to/file.war .

This will create an image called "myimage" which can then be used to create a container.

Step 3: Create a Container

The next step is to create a container using the new image. To do this, run the following command, substituting the desired port mapping:

docker run -d -p 80:8080 myimage

This will create a container based on the image and map port 80 on the host machine to port 8080 inside the container. This will allow the web application to be accessed from the host machine.

Conclusion

In this tutorial, we discussed how to deploy a Java war in a Docker container. We created an image containing the necessary components to run the application, and then created a container using the image. With these steps, you should now have a working web application running in a Docker container.