[clue-tech] upstart

[Michael J. Hammel]

On Mon, 2008-09-08 at 23:38 +0000, dennisjperkins at comcast.net wrote:
> Upstart can track daemons.  Sysvinit cannot.  If a daemon crashes,
> upstart can try to restart it automatically.  The number of restarts
> can be limited.

Actually, if you place the daemon in inittab (which can parent the
SysVInit scripts) then you get to respawn crashed (or otherwise exited)
daemons.   

Upstart tries to replace inittab too, not just the SysVInit script
structures.  I quote from the inittab file on F9:


# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.


There simply isn't a really compelling reason to do this.  Let's look at
the simple case of respawning a tty.  In F7 /etc/inittab it gets done
like this:

1:2345:respawn:/sbin/mingetty tty1

In F9 and upstart you have a script that looks like this:


start on stopped rc2
start on stopped rc3
start on stopped rc4
start on started prefdm

stop on runlevel 0
stop on runlevel 1
stop on runlevel 6

respawn
exec /sbin/mingetty tty1


I don't see this as adding any serious benefit.  In fact, I think it
makes it worse (at least for this simplistic case) since tty1 and tty2
are separate files and thus you may miss editing them to match (as they
should).  In inittab you can visually see, at a glance, they match.
That's a minor point, but I just can't see why you'd remove the inittab
usage in favor of scripting.  Extend it, sure.  That's what SysVInit
did.  Replace it?  Can't see a compelling reason.

Upstart isn't going to make hot plugged devices work better.  At best,
it will make them work different.  Change for the sake of change.  Poor
engineering, IMHO.

-- 
Michael J. Hammel                               
mjhammel at graphics-muse.org / http://www.graphics-muse.org
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