Dockerize Springboot Application

In today's world of software development, it is becoming increasingly important to be able to easily deploy and manage applications in a variety of environments. Docker is a containerization platform that allows developers to package an application and its dependencies into a container, making it easy to deploy and run in any environment. In this article, we will explore how to dockerize a Springboot application.

Prerequisites

To follow along with this tutorial, you will need:

• A Springboot application
• Docker installed on your local machine

Step 1: Create a Dockerfile

The first step in dockerizing a Springboot application is to create a Dockerfile. This file contains instructions for Docker to build a container image of your application. Here is an example Dockerfile:

FROM adoptopenjdk/openjdk11:alpine-jre
ADD target/my-app.jar my-app.jar
ENTRYPOINT ["java", "-jar", "/my-app.jar"]

Let's break down what each line of this Dockerfile does:

• FROM: This specifies the base image for our container. In this case, we are using a lightweight Java 11 image from the AdoptOpenJDK project.
• ADD: This adds the compiled Springboot application JAR file to the container image.
• ENTRYPOINT: This specifies the command that should be run when the container is started. In this case, we are running the Java Virtual Machine (JVM) and passing it the JAR file to execute.

Step 2: Build the Docker Image

Now that we have created a Dockerfile, we can use it to build a container image of our Springboot application. To do this, open a terminal window and navigate to the directory containing the Dockerfile. Then, run the following command:

docker build -t my-app .

This command tells Docker to build an image with the tag my-app using the Dockerfile in the current directory (.). Docker will execute the instructions in the Dockerfile to create the image.

Step 3: Run the Docker Container

Once the image is built, we can use it to run a Docker container that hosts our Springboot application. To do this, run the following command:

docker run -p 8080:8080 my-app

This command tells Docker to run a container using the my-app image we just built, and to map port 8080 inside the container to port 8080 on our local machine. This allows us to access the application running inside the container from our local machine.

Step 4: Test the Dockerized Application

To test that our Springboot application is running inside the Docker container, open a web browser and navigate to http://localhost:8080. You should see the home page of your Springboot application.

Congratulations! You have successfully dockerized your Springboot application.

Additional Considerations

There are a few additional considerations to keep in mind when dockerizing a Springboot application:

• You may need to modify the ADD instruction in the Dockerfile if your application has dependencies that are not included in the JAR file.
• You can use environment variables in the Dockerfile to configure your application at runtime.
• You can use Docker Compose to define and run multi-container applications.

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That's it for this post. Keep practicing and have fun. Leave your comments if any.