[systemd-devel] Changing configurations with networkd

[Tom Gundersen]

On Thu, Jul 24, 2014 at 5:59 PM, Michael Olbrich
<m.olbrich at pengutronix.de> wrote:
> On Thu, Jul 24, 2014 at 02:05:24PM +0200, Marcel Holtmann wrote:
>> > Right, I spoke too quickly. What I don't want is to preserve state
>> > between reboots, preserving it between restarts of networkd would
>> > indeed be fine. We already serialize the dhcp leases to /run, so I'd
>> > be happy to take a patch to deserialize these again when networkd
>> > starts.
>>
>> I am not sure this is useful either. It feels like a bandaid for the time
>> where networkd does not have an API to reload configuration changes. Killing
>> networkd should give you a clean start from the configuration files and not
>> magic cached value somewhere. Otherwise you end up with funny side effects
>> all the time and have to explain to users to clear some /run states. Or ask
>> them "to switch the computer off and back on again".
>>
>> When you are opting for DHCP instead of static addresses, then there is
>> really no guarantee for addresses staying the same. At least not for the
>> client to know. So unless you own the DHCP server and configure it with
>> static assignment. In all cases you have to confirm with the DHCP server that
>> you address is still valid.
>
> Getting a new IP address is not the biggest problem. But right now, when
> the valid_lft for the _old_ address is over, then then _new_ address is
> removed as well and the interface has no address at all! That is not
> acceptable. I can live with a different new address for now, but not with
> no address at all.

Indeed, this needs to be fixed. A quick fix would be to set

/proc/sys/net/ipv4/conf/all/promote_secondaries

to 1.


Cheers,

Tom