runsv and process groups (was Re: getty trouble)

[Charlie Brady <charlieb-smarden-supervision@budge.apana.org.au>]

On Fri, 20 Aug 2004, Gerrit Pape wrote:

> On Thu, Aug 19, 2004 at 01:30:46PM -0400, Dan Melomedman wrote:
> > Hello. Thanks for runit, I love it.
> > 
> > 'getty' runs fine. 'mingetty' refuses to run though, because it gets
> > EPERM on a tty open. Any ideas? mingetty used to run fine under SysV
> > init. This is RH 6.2, with the old getty and mingetty. Thanks.
> 
> Most probably it's because runsv doesn't automatically make a service
> run script a process group leader.

Gerrit, have you ever given any thought to runsv doing just that? As is, a 
runit managed system is more vulnerable than it should be to bugs in 
supervised daemons. I've had such a buggy client bring down all of runit 
stage 2. I know this is something which Dan deals with in his daemontools 
FAQ, but I think he gives a non-answer:

 How can I supervise a daemon that kills its process group? When pppd 
 receives a TERM signal, it destroys its entire process group, including 
 svscan and all my other daemons.

 Answer: The best answer is to fix the daemon. It is inexcusable for a 
 program to send signals to a process group that it didn't create. 

His answer is congruent to "programs should not have bugs".

Can you think of any reason why runsv *shouldn't* make the supervised 
process a process group leader? It'd take very little code ...

---
Charlie