[Kea-users] How to best update the KEA configuration on a HA hot-standby KEA setup

[Dan Oachs]

We also have all the main configuration in plain json files.  Like you, we
require hosts on some of our networks to be registered.  Our registration
system stores the MAC addresses in the Kea database.  For the past year or
so, this has worked really well for us.

I would highly suggest looking into storing the MAC addresses in a database
so you don't need to reload kea for every change.  You don't need to use
the database for anything else if you don't want to.   This can also be
done without any of the extra hook libraries that cost money.

--Dan



On Thu, Nov 17, 2022 at 2:19 AM Veronique Lefebure <
Veronique.Lefebure at cern.ch> wrote:

> Hi,
>
> We don't use any database for storing the KEA configuration: we use plain
> json configuration files.
> We need to update the configuration very regularly because we allow only
> known clients (pre-registered mac addresses), hence the list of
> host-reservations is quite volatile.
>
> Véronique
> ------------------------------
> *From:* Dan Oachs <doachs at gac.edu>
> *Sent:* Wednesday, November 16, 2022 6:31 PM
> *To:* Veronique Lefebure <Veronique.Lefebure at cern.ch>
> *Cc:* kea-users at lists.isc.org <kea-users at lists.isc.org>
> *Subject:* Re: [Kea-users] How to best update the KEA configuration on a
> HA hot-standby KEA setup
>
> I am curious why you are updating the config every 5 minutes.   We used to
> do that with our old DHCP server, but with Kea we moved to storing
> reservations in a database.  That way we rarely need to make changes to the
> actual Kea configuration that would necessitate a reload of the config.
>
> --Dan
>
>
> On Wed, Nov 16, 2022 at 10:27 AM Veronique Lefebure <
> Veronique.Lefebure at cern.ch> wrote:
>
> Hi,
>
> When running KEA on one single server, (no HA), and updating the KEA dhcp
> configuration file every 5 minute, using "config-set"
>
> https://kea.readthedocs.io/en/latest/arm/ctrl-channel.html?highlight=config-set#the-config-set-command
>  ,
> we can see that KEA does not reply to the DHCP requests during 30-35
> seconds while "config-set" is running.
>
> Is it expected ?
> If yes, if we add a second server in a HA hot-standby mode, can we expect
> it to answer to the DHCP requests while the first server is busy with
> config-set ?
> If yes, we need to update the second server asynchronously with respect to
> the first one, else they would both be busy with "config-set" at the same
> time.
>
> I would be interested to know how people are updating the KEA DHCP
> configuration in a HA hot-standby setup.
>
> Thanks,
> Veronique
>
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