[systemd-devel] [PATCH] networkd: fix systemd-networkd-wait-online with multiple NICs

[Nick Owens]

hello tom,

On Mon, Apr 20, 2015 at 2:32 PM, Tom Gundersen <teg at jklm.no> wrote:
> On Fri, Apr 3, 2015 at 12:48 AM, Michael Marineau
> <michael.marineau at coreos.com> wrote:
>> On Thu, Apr 2, 2015 at 3:08 PM, Nick Owens <mischief at offblast.org> wrote:
>>> hi, sorry for the delay.
>>>
>>> from http://www.freedesktop.org/software/systemd/man/systemd-networkd-wait-online.service.html:
>>>
>>> "By default, it will wait for all links it is aware of and which are
>>> managed by systemd-networkd.service(8) to be fully configured or
>>> failed, *and for at least one link to gain a carrier.*".
>>>
>>> the import part here is the end of the sentence. without this patch,
>>> systemd-networkd-wait-online will block until all configured
>>> interfaces have carrier.. you can reproduce this by running
>>> systemd-networkd in qemu with two ethernet interfaces, and issue 'info
>>> network' and then 'set_link <if> down' to simulate no carrier. then
>>> you can run systemd-networkd-wait-online, and observe that it will
>>> block until both interfaces are up, not just one.
>>>
>>> nick
>>>
>>> On Wed, Mar 25, 2015 at 10:53 PM, Andrei Borzenkov <arvidjaar at gmail.com> wrote:
>>>> On Wed, Mar 25, 2015 at 11:49 PM,  <mischief at offblast.org> wrote:
>>>>> From: mischief <mischief at offblast.org>
>>>>>
>>>>> when checking interface status, systemd-networkd-wait-online
>>>>> will continue to wait if any interface is still configuring or
>>>>> being processed by udev. this patch allows it to return if any
>>>>> one interface is degraded/routable, as per the manual.
>>>>
>>>> But current behavior is exactly what manual says: "By default, it will
>>>> wait for all links it is aware of and which are managed by
>>>> systemd-networkd.service(8) to be fully configured or failed". Or do I
>>>> miss something?
>>
>> It is worth noting that there may be some issues with tracking
>> interface states in networkd, there appear to be ways to get an
>> interface stuck in a 'configuring' state despite the fact that the
>> interface has no network config and/or has no carrier.
>
> Do you have any more info on this? Can you reproduce with current git?
> There was a fix after the last release which should fix a problem with
> enumerating devices.

the original issue was discussed at
https://github.com/coreos/bugs/issues/279. i just tested commit
cffacc741cb79f63999720525ceaa65aae01a542.

https://github.com/coreos/init/blob/master/systemd/network/zz-default.network
is our default for networkd. it seems logical that given this config,
systemd-networkd-wait-online would wait for all of the dhcp
interfaces, no matter how many.

however, i'm not sure what use case there is for this. it seems like
there's no way to wait for any one nic to be routeable/configured
without knowing its name ahead of time.

another instance of this problem is having a bridge like

[NetDev]
Name=br0
Kind=bridge

and run 'systemctl restart systemd-networkd;
/usr/bin/systemd-networkd-wait-online'. systemd-networkd-wait-online
will not return. is this intended behavior?

>
> Cheers,
>
> Tom