On Mon, Sep 25, 2023 at 08:58:32PM +0200, Andrea Bolognani wrote: > We want to make sure that, at any given time, we have either the > modular daemons or the monolithic one running, never both. In > order to achieve that, make every single modular unit conflict > with the corresponding libvirtd unit. > > We set both Conflicts=libvirtd.unit and After=libvirtd.unit: this > tells systemd that, whenever virtfood.unit and libvirtd.unit are > part of the same transaction, the former should win out. > > Thanks to this, if both the modular daemons and the monolithic > one have been enabled because of outdated automation or a simple > mistake of the administrator, the request to start libvirtd at > boot will be ignored and the result will be a regular modular > deployment. > > If the request to start libvirtd is made when the modular daemons > are already running, we have no way to prevent systemd from > complying with that request; however, thanks to the way the > conflict relationship has been declared, they will be shut down > cleanly before libvirtd is started. From the user's point of > view, the transition from modular to monolithic will be > completely transparent: it's basically the same scenario as a > regular package upgrade, just with an extra twist. > > Note that, while switching from modular to monolithic at runtime > happens automatically, going back requires manual intervention, > i.e. starting all the necessary sockets one by one. That's okay: > the goal here is to prevent misconfiguration and force of habit > to accidentally disrupt a working setup, not to encourage the > scenario. In a correctly configured and managed host, it should > never occur. > > Signed-off-by: Andrea Bolognani <abologna@xxxxxxxxxx> > --- > src/virtd-admin.socket.in | 2 ++ > src/virtd-ro.socket.in | 2 ++ > src/virtd-tcp.socket.in | 2 ++ > src/virtd-tls.socket.in | 2 ++ > src/virtd.service.in | 3 ++- > src/virtd.socket.in | 2 ++ > 6 files changed, 12 insertions(+), 1 deletion(-) Reviewed-by: Daniel P. Berrangé <berrange@xxxxxxxxxx> With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
