Spring Boot bootBuildImage example app

How to build an OCI compliant docker image with Spring Boot 2.3.0

Requirements

Installed on your machine:

clone this repository
run docker images and see the list of images you have locally
run ./gradlew bootBuildImage from this repo directory to generate an OCI image for this application
run docker images and see the new images created
you should see also spring-boot-build-docker-image-demo in the list now!
run it with docker run spring-boot-build-docker-image-demo
you can see from the output that it's running with java 11
uncomment the bootBuildImage section in build.gradle
run ./gradlew bootBuildImage again to update the image
see how only the jre layer is updated
not even the app layer is updated (even though there's a change in build.gradle!)
the app layer is not updated even if you add a new line anywhere on the source code!
run your new image always with docker run spring-boot-build-docker-image-demo
your app is now
- running with openjdk 14
- with just one line change on your gradle build file
- and only one layer (jdk) of the original image has been updated