Lightweight Spring Boot Docker image based on Alpine + Docker Compose file

Features:

• Uses lightweight openjdk:8-jre-alpine image
• Wrapper script that enables application to take PID 1 & receive SIGTERM signals (see here)
• Starts Spring Boot as spring-boot user inside the container
• Custom JAVA_OPTS
• Health check (Docker tag 1.0-healthcheck https://github.com/f-lopes/spring-boot-docker/tree/healthcheck)
• Debug mode

Available environment variables

Name	Default	Description
JAVA_OPTS		JAVA_OPTS
DEBUG	false	Enable or disable debug mode
DEBUG_PORT	8000	Debug port

How to use ?

1. Simply extend your image from flopes/spring-boot-docker and set your application name as an environment variable:

   FROM flopes/spring-boot-docker:1.1
   

2. Copy your Spring Boot executable jar into an assets folder, rename it to spring-boot.jar and build you image: docker build -t spring-boot-image .

3. Start your application:

   • Using Docker CLI docker run -d -p 8080:8080 spring-boot-image

   • Using the provided docker-compose.yml in the sample directory: docker-compose up -d

Inject environment variables:

docker run -d -p 8080:8080 -e JAVA_OPTS="-Xms256m -Xmx512m" spring-boot-image

Using Docker Compose

The docker-compose.yml file picks its configuration from the .env one.

Using this file, you can set the desired properties:

# Application properties
SERVER_PORT=8080
DEBUG_PORT=8000
SPRING_PROFILES_ACTIVE=dev
DEBUG=false
# -Dprop=... -Dparameter=...
JAVA_OPTS=

# Host properties
HOST_SERVER_PORT=8080
HOST_DEBUG_PORT=8000

Debug mode

To run the application in debug mode, simply set the DEBUG variable to true in the .env file.

Launch the application: docker-compose up -d

By default, the debug port used is the 8000.

Spring profile(s)

By default, the application will run with dev Spring profile

To run the application with a specific Spring profile, set the desired one in the .env file:

SPRING_PROFILES_ACTIVE=dev

PID 1

$ docker run -d --name spring-boot -p 8080:8080 spring-boot-extends
a5b3036136dffa34af0cdeff6153e87f9a20ba1cdc54c36fe9113b385bfb3264

lopes_f@lopes-f-laptop MINGW64 /d/WORK/git/docker-poc/docker (develop)
$ docker exec -it a5b3036136dffa34af0cdeff6153e87f9a20ba1cdc54c36fe9113b385bfb3264 sh
/app $ ps -ef
PID   USER     TIME   COMMAND
    1 spring-b   0:10 java -Djava.security.egd=file:/dev/./urandom -jar /app/spring-boot.jar
   23 spring-b   0:00 sh
   27 spring-b   0:00 ps -ef
/app $