Resolvconf trigger? (Re: #567059)

[Thomas Hood <jdthood@gmail.com>]

Hi.  I am considering introducing a trigger to the resolvconf package
in order to solve the problem (discussed in #567059) where resolvconf
is installed on a system where a caching nameserver is already running.

The problem is that, on installation, resolvconf takes control of
/etc/resolv.conf but the nameserver has not yet registered its address
(normally 127.0.0.1) with resolvconf; so when resolvconf updates the
resolv.conf file the nameserver's address is incorrectly absent.  The
problem disappears after reboot, but that is obviously not good enough.

The idea is that resolvconf activates a trigger and caching nameservers
register interest in the trigger.  When triggered, a caching nameserver
checks to see if resolvconf is now installed; if so then the nameserver
registers its IP address with resolvconf.

Questions:

1. Is this the best way to solve the problem?
2. What races and other pitfalls should I watch out for?
3. What is an appropriate name for the trigger?
4. Does anything have to be approved or discussed on a particular
   mailing list or can I go ahead and introduce the trigger and then
   ask the maintainers of caching nameservers to make use of it?

-- 
Thomas Hood