ValveSoftware
open the build definitions of the scout runtime
Having access to the build definitions could be useful for distributing games outside of Steam with the same runtime.
I'm not sure what you mean with build definitions - can you clarify?
The source used for all the scout runtime packages is available at: http://repo.steampowered.com/steamrt-images-scout/snapshots/
It's true the steam runtime could be used to distribute binaries across multiple Linux distributions without Steam. Although with the recent release of container support and our work on pressure-vessel it may be better to just use scout as a flatpak image.
What do you mean by build definitions?
All the source packages (upstream source code + packaging in dpkg/apt format) should be available in https://repo.steampowered.com/steamrt/, and also in the appropriate subdirectory of https://repo.steampowered.com/steamrt-images-scout/snapshots/. The binary .deb packages are built from those; the production versions are built in an Open Build Service instance, but anything that can build dpkg packages from source code should work, for example Debian sbuild.
The glue to generate the LD_LIBRARY_PATH runtime tarball from the binary packages are in this repository.
I don't think the glue to generate the experimental Flatpak-style runtimes is currently public, but it's basically a Steam Runtime configuration for https://gitlab.collabora.com/smcv/flatdeb/.
For the Steam Runtime 1½ 'heavy' mini-runtime that's used for the steamwebhelper, source code is in https://repo.steampowered.com/steamrt-images-heavy/snapshots/.
Sorry for the long delay and thanks for the reply.
I didn't realize that the name "scout" is used for both the traditional and the new flatpak-style runtime.
I don't think the glue to generate the experimental Flatpak-style runtimes is currently public, but it's basically a Steam Runtime configuration for https://gitlab.collabora.com/smcv/flatdeb/.
Yes, the configuration for flatdeb is exactly what I had in mind.
https://gitlab.steamos.cloud/steamrt/flatdeb-steam is now available to the public. This is not polished or set up to be a consumer product - use at your own risk, etc. - and is not something we can provide technical support for, but it should usually work.
The README in that git repository has a road-map of how the various git repositories that are involved fit together. We try to touch flatdeb and flatdeb-steam as little as possible, and do most of the changes to the installed package set by changing the steamrt package, which also has a public git repo now: https://gitlab.steamos.cloud/steamrt/steamrt/ has a branch for each runtime branch (scout, heavy, soldier), plus an experimental steamrt/sniper branch that might supersede soldier in future.