Re: [chrony-users] DHCP and Chrony

[Vincent Blut <vincent.debian@xxxxxxx>]

On Thu, Jul 18, 2019 at 03:41:28PM -0400, Patrick Whitney wrote:
> Thanks, Youssef.   That was helpful.
>
> It looks like chrony-helper is looking for DHCP leases in the location
> where dhleases drops the file.   Unfortunately, Ubuntu 18.04 does not keep
> its lease files in the same location (or format, i.e. just changing the
> location of the leases directory does not resolve the issue...).
>
> I think I have a(n extremely ugly) work around (see below), but it would be
> nice if chrony-helper could be fixed to do the right thing in Ubuntu
> 18.04.

Sure, we could extend the chrony helper script to look for NTP servers 
obtained by the systemd-networkd DHCP client but that would not be 
enough because chronyd would use them only when {re}starting.

What we need here is a systemd-networkd mechanism that updates chronyd 
*each time* it obtain a DHCP lease that comes with an NTP server option.  
Does such a mechanism exist today?

> Best,
> -Pat

Cheers,
Vincent

> workaround:  chronyc -a -m "add server `grep NTP
> /run/systemd/netif/leases/2 | sed -e 's/NTP=//'`"

By the way, the “-a” option is ignored on modern chrony version. ;-)

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