[OpenWrt-Devel] [Babel-users] [PATCH] babeld: use procd to start, stop, and respawn

Karl P karlp at tweak.net.au
Mon Sep 8 17:15:02 EDT 2014



On 09/08/2014 08:22 PM, Gabriel Kerneis wrote:
> On Mon, Sep 08, 2014 at 10:54:29AM -0700, Dave Taht wrote:
>> On Mon, Sep 8, 2014 at 6:10 AM, Baptiste Jonglez <bjonglez at illyse.org> wrote:
>>>> Additionally adds a patch to the babeld source is to prevent the
>>>> attempted recreation of a pidfile when babeld restarts uncleanly. This is
>>>> also possible to do by passing -I '' on the command line, however procd
>>>> interprets an empty argument terminating the list, and thus cannot supply
>>>> empty arguments to programs it manages.
>>
>>> Patching babeld itself is a workaround.  Why not tackle the root issue?
>>> It seems that you encountered crashes in babeld, so that should be fixed,
>>> instead of working around the crashes.  I did experience a few babeld
>>> crashes myself, but never managed to find where they came from.
>>
>> There lies the rub. If you have a deployed machine on a rooftop
>> somewhere, it is better to restart the daemon automagically and log
>> the action rather than attempt to debug it. Using procd to manage this
>> stuff reduces the probability of a babel failure taking out a node by
>> several orders of magnitude, and I strongly favor managing it this
>> way. Certainly finding and fixing bugs so that it doesn't ever crash
>> is a good option, but in the real world, nothing is perfect, and
>> defense in depth is needed.
>
> However, there is an elephant in the room here: "procd interprets an
> empty argument terminating the list, and thus cannot supply empty
> arguments to programs it manages".

More of a mouse in room.  I agree that maybe there should be a way of doing it, 
but really, you're working with a program that thinks <blah -c ''> is "good" and 
that <blah -c> is wrong?  sure, it's _legitimate_, but why make your app rely on 
what is (clearly) causing problems?

Cheers,
Karl P
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