Hypervisors are referred to by their user-facing name rather
than the name of their libvirt driver, the monolithic daemon is
explicitly referred to as legacy, and a consistent format is
used throughout.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This results in all sockets for a service being enabled when a
single one of them is.
The -tcp and -tls sockets are intentionally excluded, because
enabling them should require explicit action on the
administrator's part; moreover, disabling them should not result
in the local sockets being disabled too.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
systemd will automatically infer this dependency based on the
socket's Service=foo.service setting.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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one have been enabled because of outdated automation or a simple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@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
We already use templating to generate sockets, which are all
based off libvirtd's. Push the idea further, and extend it to
cover services as well.
This is more challenging, as the various modular daemons each have
their own needs in terms of what system services needs to be
available before they can be started, which other components of
libvirt they depend on, and so on.
In order to make this sort of per-service tweaks possible, we
introduce a Python script that can merge two systemd units
together. The script is aware of the semantics of systemd's unit
definition format, so it can intelligently merge sections
together.
This generic systemd unit merging mechanism will also supersede
the extremely ad-hoc @deps@ variable, which is currently used in
a single scenario.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
