Dockerize your Spring Boot application - Useful plugins and techniques to build efficient docker image

This repository contains sample setup for building optimised docker image and shows some useful plugins and techniques.

Features

• Efficient docker image using Layered Jars.
• Multi-stage Docker build.
• Google’s Distroless base image with healthchecks without bash or curl
• Configuring Non-root user in docker image.
• Cloud native buildpacks - with spring boot gradle plugin.
• Jib gradle plugin.
• Using docker-compose with gradle.

Getting Started

Prerequisites

• Java 11
• Docker

Installation

Step	Custom Image	Cloud native Image	Jib Image
Build image	docker build -t spring-docker-setup-healthcheck:0.0.1-SNAPSHOT .	./gradlew bootBuildImage	./gradlew jibDockerBuild
Start docker-compose	./gradlew healthcheckComposeUp	./gradlew bootAppComposeUp	./gradlew jibComposeUp
Stop docker-compose	./gradlew healthcheckComposeDown	./gradlew bootAppComposeDown	./gradlew jibComposeUp

Usage

• After successful installation, check if all applications are running docker ps e.g.

    docker ps
  
    CONTAINER ID   IMAGE                                                         COMMAND                  CREATED              STATUS                        PORTS                     NAMES
    2eab466c947d   spring-docker-setup-jib-plugin:0.0.1-SNAPSHOT                 "java -cp /app/resou…"   7 seconds ago        Up 7 seconds                  0.0.0.0:53637->8080/tcp   spring-docker-setup-jib
    9cd791a65fef   spring-docker-setup-healthcheck:0.0.1-SNAPSHOT                "java org.springfram…"   About a minute ago   Up About a minute (healthy)   0.0.0.0:53551->8080/tcp   spring-docker-setup-healthcheck
    0bfcde6a2f2e   com.rbiedrawa.docker.app/spring-docker-setup:0.0.1-SNAPSHOT   "/cnb/process/web"       2 minutes ago        Up 2 minutes                  0.0.0.0:8080->8080/tcp    spring-docker-setup

  **** Notice healthy status in our custom image.

• Next investigate how spring packaged the jars.

   cd ./build/libs
  
   # Extract jar
  java -Djarmode=layertools -jar spring-docker-setup-0.0.1-SNAPSHOT.jar extract

• Analyse created directories(application, dependencies, snapshot-dependencies and spring-boot-loader)

Other Useful Commands

Command	Description
./gradlew tasks	Display all available tasks
./gradlew bootRun	Run Spring boot application
./gradlew bootRun --args='--spring.profiles.active=docker'	Run Spring boot application with 'docker' profile
./gradlew displayDockerImageName	Displays docker image name
./gradlew displaySampleDockerCompose	Displays sample docker compose file
./gradlew bootBuildImage	Build docker image using spring boot plugin
./gradlew bootAppComposeUp	Start application using docker compose plugin
./gradlew bootAppComposeDown	Stop application using docker compose plugin
./gradlew jibDockerBuild	Build docker image using jib

References

• Production-grade Spring Boot Docker images
• Creating Efficient Docker Images with Spring Boot 2.3
• Jib plugin
• Gradle docker-compose plugin

License

Distributed under the MIT License. See LICENSE for more information.