Dockerizing a Spring Boot application involves creating a Docker image that contains your application and its dependencies. This allows you to package your application in a way that it can be easily shared and run on any machine with Docker installed. Below are step-by-step instructions for Dockerizing your Maven-based Spring Boot application and running it in a Docker container.

Step 1: Install Docker

First, ensure that Docker is installed on your local machine. You can download it from the official Docker website. Follow the installation instructions for your operating system.

If you are done with step 1 then follow the step 2

Step 2: Create a Dockerfile

In the root directory of your Spring Boot application (where your pom.xml file is located), create a file named Dockerfile without any file extension. This file will define the Docker image.

Here’s a simple example of what your Dockerfile might look like:

Note : You may encounter few issues here. Try to resolve. It shouldn't be big. For example > ERROR [internal] load metadata for docker.io/library/maven:3.8.6-openjdk-17

Step 3: Build the Docker Image

Open a terminal (command prompt or shell) and navigate to the directory that contains your Dockerfile. Run the following command to build the Docker image:

docker build -t your-image-name .

Replace your-image-name with a name you want to give your Docker image.

Step 4: Verify the Docker Image

After the build completes, verify that your image was created successfully:

docker images

You should see your image listed in the output.

Step 5: Run the Docker Container

Now you can run your Docker container using the following command:

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

This command maps port 8080 of the container to port 8080 of your host machine. Replace your-image-name with the name you used when building the image.

Step 6: Test Your Application

You can access your Spring Boot application by opening a web browser and navigating to http://localhost:8080. If everything is set up correctly, you should see your application running.

Step 7: Export the Docker Image

To share the Docker image with the other team who doesn't have internet access, you can save the image as a tar file:

docker save -o your-image-name.tar your-image-name

This will create a tarball of your Docker image that can be transferred to the other team's VM.

Step 8: Load the Docker Image on the Target Machine

Once the other team has received the your-image-name.tar file, they can load the image into their Docker environment using the following command:

docker load -i your-image-name.tar

Step 9: Run the Docker Container on the Target Machine

After loading the image, the other team can run the container with the same command:

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

Step 10: Access the Application

The application should now be accessible at http://localhost:8080 on the target machine.

Additional Notes

Database Configuration: If your application uses PostgreSQL, you may need to set up a PostgreSQL container or ensure that the database is accessible from the application. You can create a Docker Compose file to manage multiple containers (e.g., one for your app and one for PostgreSQL).

Environment Variables: If your application requires environment variables (for database configuration, etc.), you can pass them to the Docker container using the -e flag in the docker run command.

Volume Mounting: If the application needs to persist data or requires access to local files, consider using Docker volumes.

By following these steps, you should be able to successfully Dockerize your Spring Boot application and share it with the other team.

Thanks,
Kailash
JavaCharter