[SR-Users] Using DNS for Service Discovery with Kamailio

[Casco, Alessio]

Hello Daniel!

My goal is the following: I would like to use a service discovery
application (consul is an example) that dynamically guides the kamailio
back-ends. As soon as a new back-end registers into the discovery service,
kamailio will start sending traffic to it.

Since writing a module is not an option right now, I though about using DNS
and SRV records to achieve the same result, doing so I will be able to
instruct kamailio dynamically, the idea of the dispatcher group, came in my
mind only because I'd like to have something outside the main kamailio
config, so in the case I have to change the name or do some adjustments, I
don't have to restart the entire kamailio but use a RPC command for example.

Thanks
Alessio

On Mon, Jan 30, 2017 at 4:20 PM, Daniel-Constantin Mierla <miconda at gmail.com
> wrote:

> Hello,
>
> if you expect that dispatcher module will list the associated ip addresses
> with the hostname after a DNS SRV lookup, then this is not available.
>
> Dispatcher module will still use the single hostname to set r-uri (or dst
> uri) and then TM module does the lookup before sending, inside t_relay().
> Also, irc, the keepalive is sent only to the first ip resolved for a
> hostname.
>
> If you want to relay on DNS SRV for loadbalancing, you don't need
> dispatcher at all, everything is done transparently for configuration file
> by tm and core.
>
> Maybe you can detail a bit more what you want to achieve with dispatcher
> on this topic and we can think of alternatives,
>
> Cheers,
> Daniel
>
> On 26/01/2017 11:34, Casco, Alessio wrote:
>
> Thanks for your help,
>
> Unfortunately with kamailio 4.4.4, dispatcher module and your suggestions,
> I still don't see the SRV record picked up (at least using the kamcmd
>  dispatcher.list command).
>
> I didn't try the LCR module yet, I want to be sure first that dispatcher
> is not able to handle SRV first
>
> Thanks
> Alessio
>
> On Wed, Jan 25, 2017 at 8:06 PM, Jeremy Gadd <jeremygadd at gmail.com> wrote:
>
>> Holy cow, sorry about that!
>>
>> Put the hostname in dispatcher (no port or _sip._udp) and enable these:
>>
>> use_dns_cache=on
>> use_dns_failover=on
>> dns_srv_lb=on
>>
>> That's how I got it working (using the LCR module).
>>
>> On Wed, Jan 25, 2017 at 1:05 PM, Jeremy Gadd <jeremygadd at gmail.com>
>> wrote:
>>
>>> Put the hostname in dispatcher (no port) and enable these:
>>>
>>>
>>> On Wed, Jan 25, 2017 at 9:30 AM, Casco, Alessio <alessio.casco at nexmo.com
>>> > wrote:
>>>
>>>> Hello Guys!
>>>>
>>>> I'd like to be able to use SRV records inside dispatcher groups, so I
>>>> can automatise the discovery of new backends on my network using DNS
>>>>
>>>> I've tried with the following formats into the dispatcher.list file:
>>>>
>>>> $group  _sip._udp.sip-voice_backends
>>>> $group  sip-voice_backends
>>>>
>>>> and none looks to be working, running the kamailio_ctl dispatcher.list
>>>>   won't show me the group set with SRV records. ( I also try NAPTR records,
>>>> with no luck as well.)
>>>>
>>>> * Does the dispatcher module support SRV or NAPTR records? (maybe my
>>>> format is not correct)
>>>> * If not, do you have any other idea on what I could do to achieve what
>>>> I'd like to do?
>>>>
>>>> Thanks
>>>> Alessio
>>>>
>>>>
>>>> _______________________________________________
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>>>> sr-users at lists.sip-router.org
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>>>>
>>>>
>>>
>>
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>>
>>
>
>
> _______________________________________________
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>
> --
> Daniel-Constantin Mierlawww.twitter.com/miconda -- www.linkedin.com/in/miconda
> Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com
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>
>
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