Reproducible builds are currently supported for JDK versions:

• jdk-17.0.4+
• jdk-19+

Linux environment setup

To create a reproducible build you need a Linux OS environment identical to the environment of the build you want to reproduce.

What does "identical" environment mean?

So the exact environment dependencies is work in-progress, so at the present time the identical envionment can be achieved by building on the same machine as the original build, or build using a docker or podman container that was used for the same original build.

Building using the Adoptium Temurin docker images

Adoptium Temurin builds use the following docker images:

• Linux x64 : docker pull adoptopenjdk/centos6_build_image
• Linux arm64 : docker pull adoptopenjdk/centos7_build_image

Starting a container in your local directory under a workspace folder:

mkdir workspace

docker run -it -u=$(id -u):$(id -g) -w $(pwd)/workspace -v $(pwd)/workspace:$(pwd)/workspace <image> bash

Required build tooling

If you are using the Adoptium Temurin docker images, then your environment will already be setup.

Otherwise, your environment should be as specified for building the target JDK version. See: https://openjdk.org/groups/build/doc/building.html

Building a reproducible build using the temurin-build scripts

Commands:

git clone https://github.com/adoptium/temurin-build.git

cd temurin-build

export VARIANT=temurin

export JAVA_TO_BUILD=jdk

export SCM_REF=jdk-20+2_adopt (The Adoptium build tag you want to build, don't set to build HEAD)

export RELEASE=true

export CONFIGURE_ARGS=--disable-ccache

build-farm/make-adopt-build-farm.sh

Build output:

Once the build has successfully completed the built JDK archive will be available in directory:

JDK Archive: workspace/target/jdk-hotspot.tar.gz

CycloneDX SBOM: workspace/target/jdk-hotspot.json

Expected differences:

Currently identical JDK images "may" have the following differences, if building on the same physical machine as the original quite often these will be identical as well:

• jdk-19+
  • lib/server/classes_nocoops.jsa
• jdk-17.0.4+
  • lib/server/classes.jsa
  • lib/server/classes_nocoops.jsa