[systemd-devel] sigpwr.target - intended usage?

[Michael Chapman]

On Mon, 18 Jul 2016, Lennart Poettering wrote:
> On Mon, 18.07.16 14:00, Michael Biebl (mbiebl at gmail.com) wrote:
>
>> 2016-07-18 13:54 GMT+02:00 Lennart Poettering <lennart at poettering.net>:
>>> On Mon, 18.07.16 13:37, Michael Biebl (mbiebl at gmail.com) wrote:
>>>
>>>> Apparently SIGPWR is used by lxc-stop to shut down LXC containers.
>>>> What interface would you recommend instead?
>>>>
>>>> https://lists.linuxcontainers.org/pipermail/lxc-users/2015-May/009279.html
>>>
>>> Is that actually really used? I mean, upstart is pretty much dead
>>> afaics...
>>>
>>> systemd since day one shuts down cleanly on SIGRTMIN+4, and it's
>>> probably what a container manager should use (it is what machined
>>> uses). See the "Signals" section in systemd(1).
>>
>> lxc containers require sigpwr.target to be hooked up properly,
>> otherwise lxc-stop does not shutdown the container.
>
> I'd really recommend them to switch to SIGRMIN+4 instead. Redefining
> the meaning of SIGPWR like they are doing is certainly a bad idea.

On the other hand, wiring up sigpwr.target to pull in poweroff.target 
would require no changes to the systemd code, or to anybody else's code 
that happens to be using that signal correctly *or* erroneously. It's not 
as if SIGPWR has any existing defined use on systemd that would be broken 
by such a change -- we may as well make it do the same thing as sysvinit 
since we can.

- Michael