[systemd-devel] networkd losing dhcp lease with dracut / nfs root

[Tom Gundersen]

Hi Rich,

Your analysis is correct. networkd is not updating the lft.

We should change two things: dracut (or whatever is being used on your
machine) should set an infinite lifetime when using NFS root (IMHO),
and networkd should update the lft (and in particular force-set it to
infinite if CriticalConnection is being used).

The latter is on my TODO.

Cheers,

Tom

On Sat, Jun 28, 2014 at 5:19 AM, Rich Freeman
<r-systemd at thefreemanclan.net> wrote:
> I'm running systemd-212 and dracut-037, on a diskless box with an nfs
> root and pxe boot.
>
> After a number of updates I noticed that the box would freeze up after
> 24h uptime - almost exactly.  This behavior is the same whether I have
> systemd-networkd running or not (it is configured to set up any
> interface matching e* with dhcp).
>
> I traced this to the dhcp lease time - if I set the lease to 10min the
> box freezes in 10min, with errors spewing to the network console
> shortly after about not being able to reach the nfs server.
>
> After some research, I suspect it is the result of:
> https://bugzilla.redhat.com/show_bug.cgi?id=1097523
>
> I monitored the box more closely and discovered that with a 10 minute
> lease the box is renewing the lease after 5 minutes.  However, if I
> run "watch ip addr" the box counts down the valid_lft from 600 seconds
> down to 1 second with no change after 5 minutes.
>
> If I disable systemd-networkd then the box doesn't renew the lease at
> all, and valid_lft counts down just the same.
>
> I suspect that systemd-networkd is renewing the lease but not updating
> the valid_lft on the interface, and thus after the original lease
> expires the kernel brings it down.
>
> The only other thing that is odd is that my interface has two IPs
> assigned, and I have no idea where one is coming from:
> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
> state UP qlen 1000
>     link/ether 00:01:2e:31:04:dc brd ff:ff:ff:ff:ff:ff
>     inet 200.0.0.0/24 brd 200.0.0.255 scope global eth0
>        valid_lft forever preferred_lft forever
>     inet 192.168.0.10/24 brd 192.168.0.255 scope global dynamic eth0
>        valid_lft 220sec preferred_lft 220sec
>     inet6 fe80::201:2eff:fe31:4dc/64 scope link
>        valid_lft forever preferred_lft forever
>
> Clearly systemd-networkd is managing 192.168.0.10:
> Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: link is up
> Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: carrier on
> Jun 27 23:12:43 mythliv2 systemd[1]: Started Network Service.
> Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: DHCPv4 address
> 192.168.0.10/24 via 192.168.0.101
> Jun 27 23:12:43 mythliv2 systemd-networkd[442]: eth0: link configured
>
> I'm not sure where the other IP is coming from - it shows up even if I
> don't enable systemd-networkd, so perhaps dracut is setting it up.
> I'm not sure if its valid_lft of forever is causing any confusion
> though.
>
> My network config:
> [Match]
> Name=e*
>
> [Network]
> DHCP=yes
>
> [DHCPv4]
> CriticalConnection=yes
>
> (I get the same behavior if I drop the CriticalConnection=yes)
>
> Any thoughts as to what is going wrong here?  I'm happy to test patches/etc.
>
> Rich
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