When PID 1 reaches the shutdown phase, if systemd-shutdown was missing,
it'd complain loudly and freeze. Implement an internal fallback to
handle this case gracefully. The fallback is always in place, since it
makes things generally more robust and is only a little bit of code.
This shutdown is simplified, systemd issues the reboot() matching the
requested objective directly, mirroring what systemd-shutdown would do
as its final step. This skips all the cleanup systemd-shutdown normally
performs (unmounting file systems, detaching storage, killing remaining
processes, switching into the exitrd).
With SYSTEMD_LOG_LEVEL=debug:
...
[ OK ] Reached target poweroff.target.
Notify message sent to '/run/host/notify': "X_SYSTEMD_UNIT_ACTIVE=poweroff.target"
Shutting down.
OSC sequence for shutdown successfully written: ...
Failed to execute shutdown binary: No such file or directory
Powering off.
Container container has been shut down.
Zbigniew Jędrzejewski-Szmek
9edf0e839f