SIGPWR interrupt - upstart init with powstatd UPS daemon

[Scott James Remnant]

On Thu, 2007-02-15 at 18:04 -0800, Will Dickson wrote:

> Hi, I've been trying to get  powstatd to work with the upstart init 
> program on ubuntu edgy and have been having some difficulties. I 
> verified that powstatd is performing correctly - i.e.,  when the power 
> to the UPS is cut powstatd changes the entry in /etc/powerstatus from OK 
> to FAIL and sends a SIGPWR interrupt to init. Init is then suppose to 
> check the entry in /etc/powerstatus etc. However, I couldn't seem to get 
> the upstart init to respond to the SIGPWR interrupt.
> 
Right, I never included the SIGPWR code in init because I didn't know
whether it was still used or not.

> I grepped around in the upstart-0.3.5 sources and couldn't find any 
> handlers for SIGPWR. Whereas the sysvinit does have a handler for SIGPWR
> Am I missing something? Is there a way to make the upstart init work 
> with the UPS daemons?
> 
The attached patch and job file should do the trick; after installing,
you should be able to write jobs with:

	start on power-status fail
	start on power-status low
	start on power-status ok

in them.

Please let me know whether this works, so I can commit it.


In the longer term, powstatd should emit its own upstart events instead
of sending a signal -- that provides for a lot more flexibility; e.g.
you could emit a "power-level" event every time the battery charge
decreased by 5%, etc.

Scott
-- 
Have you ever, ever felt like this?
Had strange things happen?  Are you going round the twist?
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description	"Handle changes to the /etc/powerstatus file"
author		"Scott James Remnant"

start on power-status-changed

script
	PWRSTATUS=$(cat /etc/powerstatus)

	if [ $PWRSTATUS = "OK" ]; then
		initctl emit power-status ok
	elif [ $PWRSTATUS = "FAIL" ]; then
		initctl emit power-status fail
	elif [ $PWRSTATUS = "LOW" ]; then
		initctl emit power-status low
	fi
end script
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