Gradle Slimjar Docker Plugin

The gradle-slimjar-docker-plugin is a Gradle plugin designed to create Docker images for Java applications without generating a fat JAR. It ensures that Docker images have distinct layers for real code changes, separating them from unchanged dependencies bundled in a fat JAR.

Why Use This Plugin?

When dependencies are bundled in a fat JAR, the resulting application artifact becomes larger, and every code change leads to a new artifact stored in a new Docker layer. However, not all changes are substantial; unchanged dependencies shouldn't be treated as real changes and should reside in a different Docker layer from your source code.

For a more in-depth explanation of this issue, refer to the following resources:

• No Fat JAR in Docker Image
• Don't Build Fat Jars for Docker Applications

How to Use the Plugin

1. Add the Plugin to your build.gradle File:

   Add the following snippet to the plugins section of your build.gradle file. Check the Gradle Plugin page for the latest version.

   plugins {
       id 'info.developia.gradle.docker.slimjar' version '1.0.2'
   }
   

By default, the plugin uses the rootProject.name and 'latest' version to build the image name. You can override this by adding a docker block to your build.gradle file.

docker {
    repository 'my-repository'
    image 'my-application'
    version '1.0.0'
    dockerfile 'Dockerfile'
}