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 Thanks to this, if both the modular daemons and the monolithic one have been enabled because of outdated automation or a simple mistake of the administrator, the request to start libvirtd at boot will be ignored and the result will be a regular modular deployment.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> Reviewed-by: Daniel P. Berrangé <berrange@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(-) diff --git a/src/virtd-admin.socket.in b/src/virtd-admin.socket.in index 39bb0badea..42cc1f670f 100644 --- a/src/virtd-admin.socket.in +++ b/src/virtd-admin.socket.in @@ -3,6 +3,8 @@ Description=@name@ admin socket Before=@service@.service BindsTo=@service@.socket After=@service@.socket +Conflicts=libvirtd-admin.socket +After=libvirtd-admin.socket [Socket] ListenStream=@runstatedir@/libvirt/@sockprefix@-admin-sock diff --git a/src/virtd-ro.socket.in b/src/virtd-ro.socket.in index b7b7ae0dd8..7b8cbdba20 100644 --- a/src/virtd-ro.socket.in +++ b/src/virtd-ro.socket.in @@ -3,6 +3,8 @@ Description=@name@ local read-only socket Before=@service@.service BindsTo=@service@.socket After=@service@.socket +Conflicts=libvirtd-ro.socket +After=libvirtd-ro.socket [Socket] ListenStream=@runstatedir@/libvirt/@sockprefix@-sock-ro diff --git a/src/virtd-tcp.socket.in b/src/virtd-tcp.socket.in index 7c8bcdb525..9fe90ed0a0 100644 --- a/src/virtd-tcp.socket.in +++ b/src/virtd-tcp.socket.in @@ -3,6 +3,8 @@ Description=@name@ non-TLS IP socket Before=@service@.service BindsTo=@service@.socket After=@service@.socket +Conflicts=libvirtd-tcp.socket +After=libvirtd-tcp.socket [Socket] ListenStream=16509 diff --git a/src/virtd-tls.socket.in b/src/virtd-tls.socket.in index c6dceb2d4e..bb89daddb5 100644 --- a/src/virtd-tls.socket.in +++ b/src/virtd-tls.socket.in @@ -3,6 +3,8 @@ Description=@name@ TLS IP socket Before=@service@.service BindsTo=@service@.socket After=@service@.socket +Conflicts=libvirtd-tls.socket +After=libvirtd-tls.socket [Socket] ListenStream=16514 diff --git a/src/virtd.service.in b/src/virtd.service.in index 76f9c60351..60ab122cbc 100644 --- a/src/virtd.service.in +++ b/src/virtd.service.in @@ -1,9 +1,10 @@ [Unit] Description=@name@ daemon -Conflicts=libvirtd.service Requires=@service@.socket Requires=@service@-ro.socket Requires=@service@-admin.socket +Conflicts=libvirtd.service +After=libvirtd.service After=network.target After=dbus.service After=apparmor.service diff --git a/src/virtd.socket.in b/src/virtd.socket.in index aec0708fd4..053dc1c782 100644 --- a/src/virtd.socket.in +++ b/src/virtd.socket.in @@ -1,6 +1,8 @@ [Unit] Description=@name@ local socket Before=@service@.service +Conflicts=libvirtd.socket +After=libvirtd.socket [Socket] ListenStream=@runstatedir@/libvirt/@sockprefix@-sock -- 2.41.0
