How can you create a containerized application using Docker to prepare its image for deployment?

To create a containerized application using Docker and prepare an image for deployment, you need to:

1. Write a Dockerfile — a text file with instructions for building the image.
2. In the Dockerfile, specify the base image, copy the source code, install dependencies, and set the startup command.
3. Build the image with the command:

docker build -t image_name .

4. Test the image by running a container:

docker run -p 8080:8080 image_name

Example Dockerfile for a Java application:

FROM openjdk:17-jdk-slim
COPY target/app.jar /app.jar
ENTRYPOINT ["java", "-jar", "/app.jar"]

Here, we use the official OpenJDK image, copy the built jar file, and set the startup command.

After building the image, you can upload it to Docker Registry and deploy it on a server or in the cloud.