Troubleshooting boot problems

[Patrick Goetz]

> 
> Subject: Re: Troubleshooting boot problems
> From: Florian Diesch <diesch at spamfence.net>
> Date: Wed, 21 Apr 2010 12:18:40 +0200
> 
> Any event can be emitted by any program using upstart's DBus API. 
> 
> IMHO it's not that important to know where a event gets emitted
> (that's an implementation detail) but what it actually
> means. 
> 

I'm not sure I agree with this.  I understand that an event driven 
system isn't linear (see previous discussion thread) but some services 
do have linear dependencies; i.e. there are some services which can only 
be started after others (yes, I realize this is an event dependency -- 
it's still a linear relationship).

The example I provided should be adequate:  most iptables scripts start 
by flushing the tables.  If I have a custom table I need/want to have, 
it's important to me to know if ufw is running before or after my 
script, since I don't want my iptables rules to be flushed when the 
system is fully booted.  The question: does ufw run before or after the 
rc2.d scripts? is a question about a linear ordering, and an 
administrator should be able to determine this what looking at source 
code or jumping through a bunch of hoops.  Perhaps a program like 
pstree, but for events, would be useful?

Speculation about how to suspend a service is all well and good 
(commenting out the start line seems logical) but there should be an 
*official* way to do this to avoid problems down the road.