… with tools such as systemd-run/run0 much of the functionality of systemd-nspawn ended up being available for service management too (such as the pty interactivity), with only some parts remaining that only nspawn could do.
So in order to streamline things and simplify our codebase, we figured it might be nicer to eventually merge the two, or more specifically: have a full-blown implementation as part of service management, and then…
…have systemd-nspawn as a full-OS container centric frontend to it.
Hence, with this release we now add PrivatePIDs= which adds the key requirement to run full OS containers as regular system services (without any further container mgr in the mix). There is more work to be done, but one of the most basic/fundamental steps is now done.
PrivatePIDs= should really not be misunderstood as "just another sandboxing" option. Because it really isn't. It's changes semantics a lot more than…