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Heroku Cloud Native Buildpacks: JVM

This repository is the home of Heroku Cloud Native Buildpacks for JVM applications. These buildpacks build Java, Scala and other JVM language application source code into application images with minimal configuration.

[!IMPORTANT] This is a collection of Cloud Native Buildpacks, and is a component of the Heroku Cloud Native Buildpacks project, which is in preview. If you are instead looking for the Heroku Classic Buildpacks for JVM applications (for use on the Heroku platform), you may find them here: heroku/jvm, heroku/java, heroku/gradle, heroku/scala, heroku/clojure.

Usage

[!NOTE] Before getting started, ensure you have the pack CLI installed. Installation instructions are available here.

To build a JVM application codebase into a production image:

$ cd ~/workdir/sample-jvm-app
$ pack build sample-app --builder heroku/builder:22

Then run the image:

docker run --rm -it -e "PORT=8080" -p 8080:8080 sample-app

Application Requirements

Either a pom.xml file (or one of the other POM formats supported by the Maven Polyglot plugin) or a build.sbt in the root directory is required for these buildpacks to build your app.

Configuration

Procfile

A Procfile is a text file in the root directory of your application that defines process types and explicitly declares what command should be executed to start your app. Your Procfile will look something like this for Spring Boot:

web: java -Dserver.port=$PORT $JAVA_OPTS -jar target/demo-0.0.1-SNAPSHOT.jar

OpenJDK

OpenJDK Version

By default, the latest OpenJDK long-term support (LTS) release will be installed. You can configure the OpenJDK version your application needs. The buildpack tries to determine the required version in the following order:

system.properties

You can specify a Java version by adding a Java properties file called system.properties to the root directory of your application. The value of the java.runtime.version key specifies the required OpenJDK version:

java.runtime.version=21

Supported major versions are 8, 11, 17, 21 and 22. The buildpack will always install the latest release of the requested major version.

Included Buildpacks

Languages

Language buildpacks are meta-buildpacks that aggregate other buildpacks (see below) for convenient use. Use these if you want to build your application.

Build Tools

Platforms

Contributing

Issues and pull requests are welcome. See our contributing guidelines if you would like to help.