Bug#809171: Please handle network device hotplug events (move from udev)

[Guus Sliepen]

On Sun, Dec 27, 2015 at 08:58:32PM +0100, Martin Pitt wrote:

> for historical reasons the udev package has shipped the functionality
> for handling network device hotplug events. However, it's a bit weird
> to ship the coldplugging parts (/etc/init.d/networking and
> networking.service) in ifupdown, but not the hotplugging ones. It
> would be more consistent to ship both in ifupdown and also make it
> easier to do changes. Of course the systemd packagers are still happy
> to discuss changes to the udev bits and provide guidance.

That's totally fine with me.

> This involves three parts:
> 
>  * An udev rule which reacts to adding or removing network devices.
>    This is currently shipped as /lib/udev/rules.d/80-networking.rules
>    but I propose that ifupdown ships it as
>    /lib/udev/rules.d/80-ifupdown.rules to avoid a package file
>    conflict and also to make it clearer that this applies to ifupdown
>    only. I attach this as 80-ifupdown.rules.

I think we can also keep it as it is and use Replaces and Breaks
headers in the control file. Each has its drawbacks. If there is both
80-networking.rules and 80-ifupdown.rules, it seems to me like the
ifupdown script will be called twice for each hotplug event. But I agree
it will be clearer if it is called 80-ifupdown.rules.

>  * The above rule just calls an udev helper script "ifupdown" which
>    needs to be put into /lib/udev/. This does the actual work of
>    calling either ifup $IFACE directly (under SysV init or upstart) or
>    a systemd unit "ifup at IFACE.service" under systemd. The latter is
>    necessary as udev rules must not start long-running programs (ifup
>    can take quite long), and it also provides much nicer and cleaner
>    logging, a proper shutdown order, etc.
> 
>    I attach this as "ifupdown".

Ok, that's basically just a copy of /lib/udev/net.agent. Why was
/lib/udev/hotplug.functions pasted into it instead of sourced? Or is
this just a difference between the Ubuntu and Debian version of the udev
package?

>  * The ifup at .service helper unit. This should go into
> 
>      `pkg-config --variable=systemdsystemunitdir systemd`
> 
>    aka /lib/systemd/system/. It does not need to be enabled in any way
>    as the above udev helper rule will start/stop it.
> 
>    Note that this will file-conflict with udev with this name, so
>    if/once you accept this we'll need to remove the above bits from
>    udev and add a Breaks:/Replaces: to ifupdown and a Breaks: to udev.

Ok, so we'll have a file conflict in any case. I can do this in the next
release of ifupdown (0.8.5). I'll need to know which version of the udev
package to sync with.

-- 
Met vriendelijke groet / with kind regards,
      Guus Sliepen <guus at debian.org>
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