[Dnsmasq-discuss] A (possibly bad) idea: failover in dnsmasq

[Simon Kelley]

On 27/05/12 13:58, Don Muller wrote:
> I could be way off base here but here is my 2 cents. 
> 
> Maybe a better idea is to have all dnsmasq instances talking to each other listing each one with something like
> 
> partner=<ip or dns name>
> partner=<ip or dns name>
> 
> Also add two more statements. One for the primary and one for the secondaries. 
> 
> primary=yes
> 
> secondary=1 or 2 or 3 etc
> 
> Each secondary has a differenet number and when the primary fails the secondary with the lowest number takes over until the primary comes back online. You could say that master=0. 
> 
> Maybe add a heartbeat statement that specifies how often the master will send keepalive messages out so everyone else knows he is still alive and well. 


My experience if HA systems is that is the complexity increases the
probability that having an HA system _actually_ increases availability,
rather than finding nasty bugs just when you don't need the, decreases
exponentially. I really don't think that it makes sense to try and
support more than a failover pair for dnsmasq, limiting the number of
servers to two makes it much simpler, and reduces the impact of
split-brain. Hard-coding the primary/secondary eliminates all the voting
and priority stuff trivial.


> 
> Don
> 
> On May 26, 2012, at 11:18 PM, "richardvoigt at gmail.com" <richardvoigt at gmail.com> wrote:
> 
>>> Configuration on a primary looks like
>>>
>>> --failover-listen= <port no>
>>>
>>> Configuration on a secondary looks like
>>>
>>> --failover-master=<IP of primary>,<port on primary>
>>
>>
>> I think more consideration should go into the configuration command
>> names, since putting a "fallover-master" option on a secondary is
>> counter-intuitive.  After all, one doesn't put a "dhcp-authoritative"
>> option on non-authoritative servers to tell them where to find the
>> authoritative server. 

That's a valid argument. How about --failover-from=<address>

 Also, shouldn't the standby/failover behavior
>> be linked to authoritative?

I _think_ authoritative should not be used with failover, but I need to
trace through all the paths to be sure.


Simon.

>>
>> _______________________________________________
>> Dnsmasq-discuss mailing list
>> Dnsmasq-discuss at lists.thekelleys.org.uk
>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 
> _______________________________________________
> Dnsmasq-discuss mailing list
> Dnsmasq-discuss at lists.thekelleys.org.uk
> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>