Spring Boot bootBuildImage example app

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

Requirements

Installed on your machine:

• docker
• java 11

Play

• 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

Notes

• Spring Boot gradle docs
• Works also with maven and the build-image goal
• What's new in Spring Boot 2.3.0
• Spring Boot and buildpacks
• buildpacks
• Open Container Initiative