[systemd-devel] machines get killed when scopes are destroyed

[Zbigniew Jędrzejewski-Szmek]

v0lZy reported on IRC that his qemu machines get killed when shutting
down the host. libvirt-guests.service is designed to suspend them
during shutdown, but when it was run, the guests were all already dead.

And indeed, each qemu is running inside a scope, which is not
connected by any dependencies to either systemd-machine.service, or
libvirt-guests.service. libvirt-guests.service does not depend on
systemd-machine.service either. This means that when shutdown is
ordered, the scopes will stopped in parallel to other
libvirt-guests.service, and depending on timing, qemus will be just
killed with SIGTERM.

For this whole thing to work correctly, we need to ensure that
scopes are not terminated prematurely. If we introduced a target
like libvirt-ready.target, and made libvirt-guests.service be
After=libvirt-ready.target, and made all the scopes be
Before=libvirt-ready.target, I think the vms would have a chance
to shutdown properly. But that's pretty complicated.
And I'm not even sure how to do that properly. Any better
ideas?

Zbyszek