[libvirt] [RFC] daemon: remove hardcode dep on libvirt-guests
Hi, all. In virtuozzo mgmt we do not use libvirt-guests service. First because we need do extra steps on domain start and second we want to decice whether to suspend or to shutdown a domain on per domain basis. Starting is not the problem but system shutdown is. As domain in systemd based systems is just another unit we need to set ordering dependency so that domain will not be killed before mgmt service as ba79e387 do for libvirt-guest service. So let's remove this hardcode. I see 2 options. 1. Take dependant service name from config. 2. Introduce intermediate service that will specify real dependency. Looks like this one is more flexible. By the way AFAIK this is the only place that harcode libvirt-guests in libvirtd. Nikolay
On Thu, Sep 29, 2016 at 11:33:04 +0300, Nikolay Shirokovskiy wrote:
Hi, all.
In virtuozzo mgmt we do not use libvirt-guests service. First because we need do extra steps on domain start and second we want to decice whether to suspend or to shutdown a domain on per domain basis. Starting is not the problem but system shutdown is. As domain in systemd based systems is just another unit we need to set ordering dependency so that domain will not be killed before mgmt service as ba79e387 do for libvirt-guest service. So let's remove this hardcode. I see 2 options.
I don't see hard dependency anywhere in libvirtd.service, it just says Before=libvirt-guests.service
1. Take dependant service name from config. 2. Introduce intermediate service that will specify real dependency. Looks like this one is more flexible.
Do you just need to stick another service between libvirtd and libvirt-guests? If so, it should be fairly easy to do with just two additional lines in the new services: foo.service [Unit] Before=libvirt-guests.service After=libvirtd.service In case you want to get rid of libvirt-guests completely, just disable it and you can even avoid the Before=libvirt-guests.service line in your new service, although keeping it there won't hurt. Jirka
On 29.09.2016 12:21, Jiri Denemark wrote:
On Thu, Sep 29, 2016 at 11:33:04 +0300, Nikolay Shirokovskiy wrote:
Hi, all.
In virtuozzo mgmt we do not use libvirt-guests service. First because we need do extra steps on domain start and second we want to decice whether to suspend or to shutdown a domain on per domain basis. Starting is not the problem but system shutdown is. As domain in systemd based systems is just another unit we need to set ordering dependency so that domain will not be killed before mgmt service as ba79e387 do for libvirt-guest service. So let's remove this hardcode. I see 2 options.
I don't see hard dependency anywhere in libvirtd.service, it just says
Before=libvirt-guests.service
Nope, I meant this code from mentioned commit: @@ -243,8 +243,10 @@ int virSystemdCreateMachine(const char *name, iscontainer ? "container" : "vm", (unsigned int)pidleader, rootdir ? rootdir : "", - 1, "Slice", "s", - slicename) < 0) + 3, + "Slice", "s", slicename, + "After", "as", 1, "libvirtd.service", + "Before", "as", 1, "libvirt-guests.service") < 0) This makes domain a special kind of unit (scope) and sets its ordering dependency. You can't do this with libvirtd.service itself because its different unit. Nikolay
On Thu, Sep 29, 2016 at 01:00:15PM +0300, Nikolay Shirokovskiy wrote:
On 29.09.2016 12:21, Jiri Denemark wrote:
On Thu, Sep 29, 2016 at 11:33:04 +0300, Nikolay Shirokovskiy wrote:
Hi, all.
In virtuozzo mgmt we do not use libvirt-guests service. First because we need do extra steps on domain start and second we want to decice whether to suspend or to shutdown a domain on per domain basis. Starting is not the problem but system shutdown is. As domain in systemd based systems is just another unit we need to set ordering dependency so that domain will not be killed before mgmt service as ba79e387 do for libvirt-guest service. So let's remove this hardcode. I see 2 options.
I don't see hard dependency anywhere in libvirtd.service, it just says
Before=libvirt-guests.service
Nope, I meant this code from mentioned commit:
@@ -243,8 +243,10 @@ int virSystemdCreateMachine(const char *name, iscontainer ? "container" : "vm", (unsigned int)pidleader, rootdir ? rootdir : "", - 1, "Slice", "s", - slicename) < 0) + 3, + "Slice", "s", slicename, + "After", "as", 1, "libvirtd.service", + "Before", "as", 1, "libvirt-guests.service") < 0)
This makes domain a special kind of unit (scope) and sets its ordering dependency. You can't do this with libvirtd.service itself because its different unit.
IIUC, the problem is that you want to replace 'libvirt-guests.service' with a different impl ? The way systemd tends to deal with things that must be a configurable choice in this way is to define a target, and sysadmins can then make arbitrary services dependancies of that target. eg, we'd set 'Before: virt-guest-shutdown.target', and then make libvirt-guests.service be a part of that target by default. You can then have ability to turn off libvirt-guest.service and put your own custom thing inside virt-guest-shutdown.taget Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|
On 29.09.2016 13:06, Daniel P. Berrange wrote:
On Thu, Sep 29, 2016 at 01:00:15PM +0300, Nikolay Shirokovskiy wrote:
On 29.09.2016 12:21, Jiri Denemark wrote:
On Thu, Sep 29, 2016 at 11:33:04 +0300, Nikolay Shirokovskiy wrote:
Hi, all.
In virtuozzo mgmt we do not use libvirt-guests service. First because we need do extra steps on domain start and second we want to decice whether to suspend or to shutdown a domain on per domain basis. Starting is not the problem but system shutdown is. As domain in systemd based systems is just another unit we need to set ordering dependency so that domain will not be killed before mgmt service as ba79e387 do for libvirt-guest service. So let's remove this hardcode. I see 2 options.
I don't see hard dependency anywhere in libvirtd.service, it just says
Before=libvirt-guests.service
Nope, I meant this code from mentioned commit:
@@ -243,8 +243,10 @@ int virSystemdCreateMachine(const char *name, iscontainer ? "container" : "vm", (unsigned int)pidleader, rootdir ? rootdir : "", - 1, "Slice", "s", - slicename) < 0) + 3, + "Slice", "s", slicename, + "After", "as", 1, "libvirtd.service", + "Before", "as", 1, "libvirt-guests.service") < 0)
This makes domain a special kind of unit (scope) and sets its ordering dependency. You can't do this with libvirtd.service itself because its different unit.
IIUC, the problem is that you want to replace 'libvirt-guests.service' with a different impl ?
The way systemd tends to deal with things that must be a configurable choice in this way is to define a target, and sysadmins can then make arbitrary services dependancies of that target.
eg, we'd set 'Before: virt-guest-shutdown.target', and then make libvirt-guests.service be a part of that target by default. You can then have ability to turn off libvirt-guest.service and put your own custom thing inside virt-guest-shutdown.taget
Thanx!
participants (3)
-
Daniel P. Berrange -
Jiri Denemark -
Nikolay Shirokovskiy