[Kea-users] Default configuration for kea-lfc

Tomek Mrugalski tomasz at isc.org
Mon Nov 21 18:37:19 UTC 2016

W dniu 19.11.2016 o 18:21, Patrik Lundin pisze:
> I have noticed that the example kea.conf in 1.1.0 does not configure
> a lfc-interval, meaning kea-lfc is disabled. Are there any reasons you
> would ever run without LFC in normal production situations, since this
> means you will (eventually) fill the partition that hosts the lease
> file?
No. LFC is reasonable to be enabled every time a memfile backend is
used. It is not needed for MySQL, PostgreSQL or Cassandra.

> If you generally are expected to run with LFC then I guess it would be
> helpful to either specifically set a lfc-interval in the configuration
> example as a hint to users, or go one step further and automatically set
Yes, that's a good suggestion. Can you open up a ticket for it?

> lfc-interval to some middle-of-the-road timeout when the database type
> is memfile and no specific lfc-interval is configured.
That would be good. One problem with its implementation is that the way
our current configuration parsers are implemented is messed up. The code
creates an independent parser object for each scope (a list, object or
JSON entry). This approach caused us to have lots of small parsers that
are able to parse specific part of the config. The side effect is that
the parser objects are only created for entries that are present in the
config file, which makes default values for entries not present
difficult to implement. We did several workarounds for that, but they
are kludgy at best.

The good news is that we're aware of the problem and decided to devote
significant part of upcoming 1.2 release to refactor, or even partially
rewrite the configuration parsers. Having the ability to specify default
values is certainly in scope of that work. See item #6 in ticket #5014

To wrap this up, if you open a ticket, I can have the configs updated in
no time. Fixing the default value will take longer, but that's
definitely something we will have fixed in 1.2.

Tomek Mrugalski

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