Proton/docker

Proton (soldier) SDK

These are the build rules that are used to create docker images to build Proton. The automated creation of the official images lives in https://gitlab.steamos.cloud/proton/soldier/sdk, but this can be used to create local images too.

Local usage

The protonsdk_version make variable will override which image is used to build Proton, but may not trigger a full rebuild, so building from scratch may be necessary.

Building Proton with a locally build docker image, instead of using the official images, can be done by using protonsdk_version=local. This may be used for instance to test changes to the docker image recipes.

Or, it is also possible to build the docker images first by invoking make protonsdk and it will tag the images with the protonsdk_version variable value.

Official images

To update the official Proton SDK images:

1. Update the image build rules, STEAMRT_VERSION and PROTONSDK_VERSION version numbers in this folder, test locally, commit and push the changes.

2. Update .gitlab-ci.yml in the Proton SDK repository to point to the new commit, commit and push to trigger a new build of "-dev" images.

3. Once the images are satisfying, tag the version in Proton SDK repository and push the tag, this will trigger a new build of the images and version them with the same tag as the Git tag.

4. Once the images have been published, update the default arg_protonsdk_image version number in configure.sh to use the newly built images by default.

Any change or addition to GPL-ed source first requires to update or add the corresponding source to https://repo.steampowered.com/proton-sdk. The SOURCES_URLBASE variable must be used to download the sources from there, and its sha256 must be added to validate the sources in the same way the existing code does.

Technical details

The images are built incrementally, with intermediate images created for each component of the toolchain, then assembled together in a single proton image.

The reason behind this is to optimize the use of docker cache, so that components that didn't change do not require to be rebuilt every time, saving a lot of time in the build process, when only small additions are made.

It also lets us build several components of the toolchain separately, in parallel. This is especially the case when building the images on the https://gitlab.steamos.cloud CI.

Because the ARG parameter in Dockerfile doesn't behave nicely with docker caches it is avoided, and Dockerfile.in are used with variable replacements done using sed.

The https://gitlab.steamos.cloud CI uses Kaniko instead of Docker, with a bit of script conversion to generate commands usable there. More details are available in Proton SDK.

The build-base images are there to create a common ground to build the other elements of the toolchain. They are based on fairly recent (more than what steamrt provides), but they are only used temporarily to build a static version of the Binutils, MinGW and GCC binaries, which are then copied over the steamrt base image.