On Mon, Jun 9, 2014 at 11:17 AM, Giancarlo Razzolini
<grazzol...@gmail.com> wrote:
> Em 09-06-2014 12:03, sven falempin escreveu:
>> ifstated is a cool FSM emgine for handling the carp problems,
>> for more complex need , instead of hacking this not complete FSM engine,
>> i would just used another software.
>>
>> The last time, i just use plain perl script, because it was convenient
>> and easy to read,
>> using a true FSM design was just making the logic more complex.
>>
>> IMHO the way to improve ifstated is to fork it so it becomes a full FSM
>> engine,
>> with transition and node definition, and each part using perl or ksh code.
>>
>> node 1 {
>> entry : {perl code}
>> leaving: {ksh code}
>> eventX : node 2
>> }
>>
>> The all work would be on the eventX , how to create one in a cron like
>> process, how to bind the superb kqueue, and
>> how to get notified from the network states change.
>>
>> Now , if ifstated is not able to handle what it was design for (CARP)
>> i guess it should be fixed.
> It definitively does what it was designed for. But I believe that these
> improvements would also benefit carp only deployments. If a carp node is
> failing more than N times in the last few minutes, it might be a good
> idea to completely fail it over and enter on a different state. I use my
> ifstated setup for both carp and isp link failure detection. I took a
> look at ifstated code and I've been fiddling with it for a little time
> now. I believe that the counter based approach is easy to implement with
> less disruption. The time based one is more difficult. As I mentioned,
> I've been using ifstated for years now (10+ IIRC). And more often than
> not, isp links behave erratic. Carp can also have problems if the
> network hardware underneath it does not behave correctly. I don't
> believe that all of these situations can be solved even with a true FSM.
> That's why I'm proposing these improvements. But, I wanted to discuss
> with you guys here on tech@ first. Perhaps something entirely different
> needs to be done.
>
Detecting bad network is problematic, i try to access external service for this,
dns and tcp, this can be done inside ifstated.
For the counter, you could use a file and modified it from ifstated,
and do a if grep 10 /my/file
echo "my file reach 10"| mail -s alert root; call real action; erase file,
but lets wait for people with more insight :-)
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