Dockerfile for Spring Boot in Spring Boot - Mini Project: Build & Apply

Dockerfile for Spring Boot

📖 Scenario: You have created a simple Spring Boot application and want to package it into a Docker container. This will help you run your app anywhere without worrying about the environment setup.

🎯 Goal: Build a Dockerfile that creates a Docker image for your Spring Boot application. The Dockerfile will start from a base Java image, copy your app's jar file, and set the command to run it.

📋 What You'll Learn

Create a Dockerfile starting from the OpenJDK 17 base image

Copy the Spring Boot jar file named app.jar into the image

Set the command to run the jar file using java -jar app.jar

Expose port 8080 for the application

💡 Why This Matters

🌍 Real World

Dockerizing Spring Boot apps is common to deploy them easily on cloud servers or local machines without setup issues.

💼 Career

Knowing how to write Dockerfiles for Java apps is a key skill for DevOps engineers and backend developers working with containerized deployments.

1

Create the base image

Write a line in the Dockerfile to use the OpenJDK 17 image with slim version as the base image. Use FROM openjdk:17-slim.

Spring Boot

# Your code here

Need a hint?

The FROM instruction sets the base image for your Docker image.

2

Copy the Spring Boot jar file

Add a line to copy the file named app.jar from your project folder into the Docker image's root directory. Use COPY app.jar /app.jar.

Spring Boot

FROM openjdk:17-slim
# Your code here

Need a hint?

The COPY instruction copies files from your computer into the Docker image.

3

Expose port 8080

Add a line to expose port 8080 in the Dockerfile using EXPOSE 8080. This tells Docker the app listens on this port.

Spring Boot

FROM openjdk:17-slim
COPY app.jar /app.jar
# Your code here

Need a hint?

The EXPOSE instruction documents the port your app uses.

4

Set the command to run the app

Add a line to run the Spring Boot jar file using CMD ["java", "-jar", "/app.jar"]. This tells Docker how to start your app.

Spring Boot

FROM openjdk:17-slim
COPY app.jar /app.jar
EXPOSE 8080
# Your code here

Need a hint?

The CMD instruction sets the default command to run when the container starts.