Dockerizing your Spring Boot Application

Dockerizing your Spring Boot Application. Creating a Docker container for a Spring Boot application allows you to deploy and scale your application seamlessly across different environments. This tutorial provides a step-by-step guide to dockerize your Spring Boot application.

Prerequisite

Before you start, ensure that you have the following installed:

1. Java: Spring Boot typically uses Java, so make sure you have Java installed. you can use JDK 8 or higher.
2. Maven or Gradle: These are the most common build tools for managing Spring Boot projects.
3. Docker: You need Docker installed on your machine to build and run the Docker container.

Create a Spring Boot Application

If you don’t already have a Spring Boot application, you can create one using Spring Initializr.

• Go to the Spring Initializr Website
• Choose your preferred product metadata(Group, Artifacts, etc)
• Add dependencies you might need.
• Click on Generate to download your project.

Add a Dockerfile to your Application

Create a file named 'Dockerfile'in the root directory Spring Boot application with the following content.

# Use the official OpenJDK image as the base image
FROM openjdk:8-jdk-alpine

# Set the working directory inside the container
WORKDIR /app

# Copy the jar file into the container
COPY target/*.jar app.jar

# Expose the port the app runs on
EXPOSE 8080

# Run the jar file
ENTRYPOINT ["java", "-jar", "/app/app.jar"]

Explanation:

• 'FROM openjdk:8-jdk-alpine': This line tells Docker to use the OpenJDK 8 image as the base.
• 'WORKDIR /app': Sets the working directory for any RUN, CMD, ENTRYPOINT, COPY, and ADD commands.
• 'COPY target/*.jar app.jar': Copies the built jar file from the target directory to the Docker image as ‘app.jar’.
• 'EXPOSE 8080': Exposes port 8080 to enable networking between the container and the outside world.
• 'ENTRYPOINT': Specifies the command to run within the container.

Build the Application

Before creating a Docker image, you need to build your Spring Boot application. Navigate to your project directory in the terminal and run:

If using Maven:

mvn clean package

If using Gradle:

gradle build

This command builds your application and creates a jar file in the 'target/'or 'build/libs/'directory.

Build the Docker Image

Now, build your Docker image using the following command in the terminal.

docker build -t springboot-application .

This command builds the Docker image using the Dockerfile in your current directory and tags the image as 'springboot-application'.

Run the Docker Container

To run your docker container, use :

docker run -t 8080:8080 springboot-application 

This command runs the docker container and maps port 800 of the container to port 8080 on your host allowing you to access the application via 'localhost:8080'.

Note: You can change the port number to your requirement or preference.

Dockerizing your spring boot application is a straightforward process that can significantly simplify deployment and scaling in the production environment.

Happy Coding & Learning

See Also

• Python Program for Linear Search
• How to Sort Dictionary by Value in Python