[libvirt-users] signal for shutdown in lxc driver

[Boris Savelev]

2015-11-20 18:19 GMT+03:00 Daniel P. Berrange <berrange at redhat.com>:
> On Fri, Nov 20, 2015 at 04:19:59PM +0300, Boris Savelev wrote:
>> Hello!
>>
>> Try to use libvirt with lxc.
>> I use latest centos6 amd64 as a libvirt host (libvirt from xen4 repo)
>> libvirt-daemon-1.2.15-3.el6.x86_64
>> In container I also use latest centos6 amd64. Container starts with
>> /sbin/init. CentOS 6 came with upstart as default init.
>>
>> My problem is that I could not shutdown container correctly with libvirt.
>> virsh -c lxc:/// shutdown test
>> Domain test is being shutdown
>> In container I see only:
>> "init: Re-executing /sbin/init"
>> in syslog messages
>>
>> Why it is happened?
>> lxcDomainShutdownFlags [1] send SIGTERM to initpid. Upstart got it and
>> reloaded himself instead shutdown. It's default behavior... [2]
>> The question is why libvirt send SIGTERM? As I can see lxc-stop [3]
>> send SIGPWR (that works correctly with upstart) and also have ability
>> to change default signals.
>>
>> I can understand that when container start with some script not
>> /sbin/init that handle SIGTERM this situation is ok. But then
>> container use /sbin/init it is not.
>
> The choice of signal is essentially abitrary, since there is no
> common standard used across different init systems. As such we
> chose signal numbers that were useful in the context of containers
> running applications (ie containers with an init). We then added
> logic to be able to use /dev/initctl to trigger shutdown of init
> based containers.  This works with sysvinit and with systemd,
> and various other init systems, but it seems upstart does not
> support this. If there is another mechanism for instructing
> upstart to shutdown that we can reliably detect, then we could
> use that.
>

Yes, I agree. In this case signal could be configurable (like in generic lxc).
You are right, upstart doesn't support /dev/initctl (
But upstart shutdown correct with SIGPWR (30).

-- 
Boris