sysext: add support for SYSEXT_LEVEL

[thkukuk]

mkosi commit the issue has been seen with

main

Used host distribution

openSUSE Tumbleweed

Used target distribution

openSUSE Tumbleweed

Linux kernel version used

6.11.0-1-default

CPU architectures issue was seen on

x86_64

Unexpected behaviour you saw

Another feature request: openSUSE MicroOS and Tumbleweed are rolling releases with a new VERSION_ID every day. mkosi uses "ID=" and "VERSION_ID=" from /etc/os-release, which means a new sysext image is needed every day, while purely technical, this is not necessary.

systemd-sysext prefers SYSEXT_LEVEL over VERSION_ID for this reason:

If the extension ID= is not "_any", the SYSEXT_LEVEL= field (if defined) has to match. If the latter is not defined, the VERSION_ID= field has to match instead.

It would be nice if mkosi would follow the same rules for creating the extension-release file: if /etc/os-release contains SYSEXT_LEVEL, add that to extension-release.d/*. If not, use VERSION_ID as of today.

Used mkosi config

No response

mkosi output

No response