A fundamental concept of all openSUSE packages as well as any image offered for download is a fully transparent, reproducible and automatic build and development process based on sources.
In openSUSE developers do not perform manual builds on some specially crafted machine in their basement and then upload the result somewhere. Instead all sources are stored in a version control system inside the open build service (OBS) instance at build.opensuse.org. OBS then automatically builds the sources including all dependencies according to defined build instructions (eg spec files for rpms). OBS also automatically adds cryptographic signatures to files that support it to make sure nobody can tamper with those files.
The WSL appx files are basically zip files that contain a tarball of a Linux system (like a container) and a Windows exe file, the so called launcher. Building a container is something OBS can already do fully automatic by means of Kiwi. The launcher as well as the final appx however is typically built on a Windows machine using Visual Studio by the developer.
Since the goal of the openSUSE WSL offering is to have the appx files officially and automatically be produced along with other images such as the DVD installer, Live images or containers, the appx files have to be built from sources in OBS.
Combining that all together OBS can actually build the WSL appx from sources. The current state of development can be found in the Virtualization:WSL project in OBS. The generated appx files are published on download.opensuse.org.
The current images for Leap 15.2 Alpha and Tumbleweed there are good enough for some testing already so please go ahead and do so, feedback welcome!
Note that since the appx files are signed by OBS rather than Microsoft, there are a few steps required to install them.
Going forward there is still quite some work needed to polish this up. Kiwi for example can’t build the appx directly itself but rather the fb-util-for-appx is called by a spec file. That requires some hacks with the OBS project config to work. On Linux side there’s currently no password set for the root user, so we need a better “first boot” solution. More details on that in a later article. Meanwhile, remember to have a lot of fun…