[Dnsmasq-discuss] Configuration in dynamic storage?

Niels Basjes dnsmasq at basjes.nl
Sat Apr 13 10:23:50 BST 2013


Hi Simon,

Thanks for clarifying and giving insights into your long term ideas.

Niels Basjes


On Fri, Apr 12, 2013 at 11:42 AM, Simon Kelley <simon at thekelleys.org.uk>wrote:

> On 10/04/13 19:31, Niels Basjes wrote:
>
>> Hi,
>>
>> Yes, that is what I have now.
>> But why the reload of dnsmasq for trivial changes?
>>
>> Wayback I've played with an LDAP connector for the ISC DHCPD and I was
>> simply wondering if dnsmasq has a similar feature (or if it would even be
>> possible to have for dnsmasq).
>>
>>
> Regardless of the source of configuration information, I'd be very wary of
> adding something which makes live queries against any database system.
> There are a couple of reasons for this: firstly, to keep the memory
> footprint small, dnsmasq controls concurrency quite carefully. If there was
> a database lookup which might block in the main codepath, either dnsmasq
> would have to bloat to allow more concurrent processing of DNS queries, or
> it would have to run the risk that database-access blocking  would stop all
> DNS queries for the duration.
>
> Secondly, there's a massive risk of deadlock, can be guarantee that your
> database backend never needs to make a DNS query? If not your risk the
> database waiting on dnsmasq, whilst dnsmasq is waiting on the database, and
> both will wait forever.
>
> I have a long-term vision of fixing the configuration system which
> involves:
>
> 1) Splitting the config into that which requires a restart and that which
> doesn't.
>
> 2) Providing a modular API to allow the configuration which doesn't
> require restart to come from any source. One of these would be the
> traditional config file, of course.
>
> 3) Coding a way to re-read the configuration via the above module(s) and
> then atomically insert the new config without stopping dnsmasq, which would
> allow the configuration module to access LDAP or databases without the risk
> of deadlock via DNS queries.
>
>
> Cheers,
>
>
> Simon.
>
>
>
>> On Wed, Apr 10, 2013 at 8:13 PM, sven falempin<sven.falempin at gmail.**com<sven.falempin at gmail.com>
>> >wrote:
>>
>>  why a database in your case ?
>>>
>>> kill -HUP
>>> init.d/... reload
>>>
>>> <<
>>> DNSMASQ considerations
>>>
>>> If using dnsmasq, the template file is /etc/cobbler/dnsmasq.template but
>>> it basically works as for ISC (above). Remember that dnsmasq also
>>> provides
>>> DNS.
>>>
>>>
>>>
>>>>>
>>>
>>> On Wed, Apr 10, 2013 at 8:57 AM, Niels Basjes<dnsmasq at basjes.nl>  wrote:
>>>
>>>  Hi,
>>>>
>>>> Is it possible to store the config of dnsmasq in some kind of database?
>>>> What I would like is to be able to have an other tool (like cobbler) to
>>>> update the config (i.e. add/remove host definitions, cnames and such)
>>>> without the need to restart dnsmasq.
>>>>
>>>> Is this possible?
>>>>
>>>> --
>>>> Met vriendelijke groeten,
>>>>
>>>> Niels Basjes
>>>>
>>>> ______________________________**_________________
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>>>> Dnsmasq-discuss at lists.**thekelleys.org.uk<Dnsmasq-discuss at lists.thekelleys.org.uk>
>>>> http://lists.thekelleys.org.**uk/mailman/listinfo/dnsmasq-**discuss<http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss>
>>>>
>>>>
>>>>
>>>
>>> --
>>>
>>> ------------------------------**------------------------------**
>>> ------------------------------**---------------------------
>>> () ascii ribbon campaign - against html e-mail
>>> /\
>>>
>>>
>>
>>
>>
>>
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>>
>
>
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>



-- 
Met vriendelijke groeten,

Niels Basjes
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