Optional features allow distros to define sets of transfers that can
be enabled or disabled by the system administrator. This is useful for
situations where a distro may want to ship some resources version-locked
to the core OS, but many people have no need for the resource, such as:
development tools/compilers, drivers for specialized hardware, language
packs, etc
We also rename sysupdate.d/*.conf -> sysupdate.d/*.transfer, because
now there are more than one type of definition in sysupdate.d/. For
backwards compat, we still load *.conf files as long as no *.transfer
files are found and the *.conf files don't try to declare themselves
as part of any features
Fixes https://github.com/systemd/systemd/issues/33343
Fixes https://github.com/systemd/systemd/issues/33344
Makes it possible to specify URLs to a changelog and an appstream
catalog XML in the sysupdate.d/*.conf files. This will be passed along
to the clients of systemd-sysupdated, which can then present this data.
We set up a NOTIFY_SOCKET to get download progress notifications from
each individual import helper. Along with the number of import jobs we
have to run, this gives an overall progress value which we report using
sd_notify
Daan De Meyer
Adrian Vovk
Abderrahim Kitouni
Lennart Poettering