Docker Best Practices for Spring Boot

Docker Best Practices for Spring Boot Applications

As a Senior Java Spring Boot Docker Kubernetes AWS Architect, I have worked with numerous Spring Boot applications that are deployed in containerized environments. In this blog post, I will share some best practices for Dockerizing your Spring Boot applications.

1. Use a Multi-Stage Docker Build

One of the best practices for optimizing Docker images is to use a multi-stage Docker build. The idea behind a multi-stage build is to use one container for building your application, and another container for running your application.

FROM maven:3-jdk-17 as build
COPY ./pom.xml .
COPY ./src ./src
RUN mvn clean package -DskipTests

FROM openjdk:17-jdk-slim
COPY --from=build /app/target/*.jar /app.jar
EXPOSE 8080
CMD ["java", "-jar", "app.jar"]

Diagram 1: Multi-Stage Docker Build

+---------------+
|  Maven Build  |
+---------------+
      |
      |
      v
+---------------+
|  Final Image  |
|  (optimized)  |
+---------------+

2. Minimize the Size of Your Docker Image

The smaller the Docker image, the faster it will be to deploy and the less disk space it will require. You can minimize the size of your Docker image by:

Removing unnecessary packages
Using a smaller base image
Removing unnecessary files

Diagram 2: Minimized Docker Image

+---------------+
|  Spring Boot  |
|  Application  |
+---------------+
      |
      |
      v
+---------------+
|  Minimized    |
|  Docker Image  |
+---------------+

3. Use the `--no-install` Flag

When building a Docker image, the --no-install flag can be used to prevent unnecessary packages from being installed. For example:

FROM ubuntu:20.04

# Install necessary packages without installing unnecessary ones
RUN apt-get update && apt-get install -y --no-install-recommends \
    openjdk-17-jdk-headless \
    && rm -rf /var/lib/apt/lists/*

Diagram 3: Using the `--no-install` Flag

+---------------+
|  Ubuntu Base  |
|  Image        |
+---------------+
      |
      |
      v
+---------------+
|  Minimized    |
|  Docker Image  |
+---------------+

4. Use a Docker Volume

A Docker volume is a way to persist data between container restarts. You can use a Docker volume to store your application's data and configuration.

version: '3'
services:
  app:
    build: .
    ports:
      - 8080:8080
    volumes:
      - ./data:/app/data
      - ./config:/app/config

Diagram 4: Using a Docker Volume

+---------------+
|  Spring Boot  |
|  Application  |
+---------------+
      |
      |
      v
+--------------------+
|  Docker Volume     |
|  (persistent data) |
+--------------------+

5. Use a Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. You can use Docker Compose to define a multi-container application that includes your Spring Boot application and any necessary dependencies.

version: '3'
services:
  app:
    build: .
    ports:
      - 8080:8080
    depends_on:
      - db
  db:
    image: postgres
    environment:
      - POSTGRES_DB=mydb
      - POSTGRES_USER=myuser
      - POSTGRES_PASSWORD=mypassword

Diagram 5: Using Docker Compose

+---------------+
|  Spring Boot  |
|  Application  |
+---------------+
      |
      |
      v
+--------------------+
|  Docker Compose    |
|  (multi-container) |
+--------------------+

By following these Docker best practices for Spring Boot applications, you can optimize your Docker images for faster deployment and lower disk usage. Remember to always follow the principle of keeping your Docker images as thin and lightweight as possible.

Docker Best Practices for Spring Boot