[Kea-users] Managing Large Number of Static Leases

[Darren Ankney]

Hi Dave,

Usage of a database server with Kea is completely optional.  You are
free to use the configuration file for all of your configuration
needs.  Leases may be stored in a file on the disk as well.  Database
is not required for redundancy either (see the HA hook).  The only
situation I can think of where database server usage would be required
is if you wanted to manage host reservations with the Stork GUI, which
does indeed require this as it is not able to manage host reservations
that are stored in the configuration file.  Most of the time, it is
better, if possible in your environment, to not use a database server
with Kea as the database queries that Kea must make actually decrease
performance.

Thank you,
Darren Ankney

On Mon, Apr 21, 2025 at 2:07 PM Dave Hall via Kea-users
<kea-users at lists.isc.org> wrote:
>
> Hello,
>
> As we are starting to plan for an eventual migration from ISC DHCP to Kea, we have some concerns about how we will map our current usage and procedures.
>
> (If this has been discussed elsewhere, my apologies.  I tried to search the archives, but perhaps not with the correct terminology.)
>
> In our current practice we rely extensively on DHCP Static Leases (Host Reservations?) for network management in a data center setting with a large number of servers.  Further, we use DNS names rather than IP addresses in our DHCP config file, which allows us to reconfigure IP addressing completely within BIND.
>
> This strategy allows us to avoid static host configurations and to be able to swap new hardware into a given position simply by changing the MAC address in the DHCP config file.  We also use this mechanism to configure the BMC for our servers so that the BMC DNS name is consistent with the host DNS name.  Further, we tend assign IP addresses based on physical location - the row number, rack number, and position in the rack are encoded in the IP.
>
> Thus, I am a bit concerned about how we will manage this with Kea, which appears to be based on the use of a database server.  Is there any utility or tool that can translate back and forth between a flat, human readable file and the database representation, or perhaps that provides a virtual file representation of the database table containing static leases?
>
> Overall, while I understand how DHCP redundancy and failover are facilitated by using a database, especially in a predominately dynamic-lease environment.  However, I also see a potential loss of capability in the shift away from flat configuration files, particularly in terms of scripting DNS and Static DHCP entries for large deployments.
>
> I am also somewhat concerned that Kea relies on an external service with non-trivial management requirements.  In my mind this adds significant complexity to what has always been a light and crucially fundamental network service.
>
> For what it's worth, in my ideal world a restart of the 'primary' Kea server would cause the static lease table to be dropped and reloaded from flat files similar to those used with the current DHCP server.  Also, an optimized replication-capable database would be embedded within the Kea binary.  (Replication could be packaged as an add-on.)  This would keep it simple for the small users and yet seamlessly scale for the really large users.
>
> Thanks.
>
> -Dave
>
> --
> Dave Hall
> Binghamton University
> kdhall at binghamton.edu
>
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