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

Daniel-Constantin Mierla miconda at gmail.com
Tue Jan 31 12:47:21 CET 2017


Hello,

someone published a npm package for etcd-based discovery service, which
sounds similar to what you want to do:

  -
https://www.kamailio.org/w/2015/10/kamailio-dispatcher-discovery-service-with-nodejs-and-etcd/

Alternative to dispatcher, you can also consider using rtjson module to
push back destinations to kamailio in a json document via some API service.

But if you want to watch the state of destinations, then dispatcher is
the way to go.

Cheers,
Daniel


On 31/01/2017 11:28, Casco, Alessio wrote:
> 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 <mailto: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 <mailto: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 <mailto: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
>>             <mailto: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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>>
>>
>>
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>>
>>
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>
>     -- 
>     Daniel-Constantin Mierla
>     www.twitter.com/miconda <http://www.twitter.com/miconda> -- www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
>     Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com <http://www.asipto.com>
>     Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com <http://www.kamailioworld.com>
>
-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com
Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com
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