Re: pidsig 0.11 - a fghack like de-daemonisation tool

[Wayne Marshall <wcm@guinix.com>]

On Fri, 4 Jun 2010 13:21:18 -0400 (EDT)
Charlie Brady <charlieb-supervision@budge.apana.org.au> wrote:

> 
> On Fri, 4 Jun 2010, Wayne Marshall wrote:
> 
> > On Fri, 4 Jun 2010 12:54:46 -0400 (EDT)
> > Charlie Brady <charlieb-supervision@budge.apana.org.au>
> > wrote:
> > 
> > > > On Thu, 3 Jun 2010 21:25:30 +0200
> > > > Laurent Bercot <ska-supervision@skarnet.org> wrote:
> > > > 
> > > > > Strong supervision makes sure that your supervisor
> > > > > process tree is *always* alive and complete, unless
> > > > > process 1 itself crashes, in which case you're doomed
> > > > > to reboot anyway.
> > > 
> > > There is a weakness in this "strong supervision" model. Any
> > > service with a 'down' file will not be restarted if its
> > > supervise/runsv or svscan/runsvdir is replaced.
> > 
> > Why do you describe this as a "weakness"?  The down flagfile
> > is consulted only on startup of the supervisor.  If the
> > administrator has configured the service to be down on
> > startup, presumably she wants it to be down on startup.
> 
> I thought that we were discussing here the situation where the
> supervisor dies and is automatically restarted. That is not
> the 'on startup' where the adminstrator intends the service to
> be down. "on startup" is long gone, and the adminstrator has
> started the service, and wants it to continue running. The
> automated restart of the supervisor shouldn't change that
> running state.
> 

Well, the down flagfile is relevant on startup of the
supervisor.  Starting/restarting the supervisor may occur at
system boot, and/or any number of times thereafter.  Supervisors
do not normally need to know or care between system boot and
"thereafter".

If the administrator needs to differentiate between system boot
and "thereafter", she will have probably need to effect that
differentiation through her system boot/shutdown scripts.  But
that is her problem, rather than a weakness in the supervisory
model.

Cheers,

Wayne