Nut upsuser - Jan 2023 - confusion about shutdown

On Dec 30, 2022, at 7:42 PM, Greg Troxel <gdt at lexort.com>
wrote:
> 
> maybe me, maybe docs.
> 
> I have never had auto shutdown set up on netbsd.  Mostly I monitor to
> mqtt.  But now I'm trying and have multiple confusions.
> 
> 1) 'upsdrvctl shutdown' vs 'upscmd shutdown.return'
> 
> upsdrvctl is about stopping the driver, but lowbatt shutdown wants to
> send a command.  I don't get the upsmon example file:
"upsdrvctl stop" is for stopping the driver, but "upsdrvctl
shutdown" runs "$DRIVER -k" to kill power to the load on the UPS
(which is actually a second, non-long-running instance of the driver that
doesn't talk to upsd, after the rest of the system is ready to stop).

That being said, upscmd needs to talk to upsd, which needs a running driver -
IMHO this is only workable if you trust your delay-before-shutdown in the UPS.
The "upsdrvctl shutdown" case can often be run after everything has
been remounted read-only, at which point it is okay if there is no delay before
the power gets pulled.
> 
>  # POWERDOWNFLAG - Flag file for forcing UPS shutdown on the primary system
>  #
>  # upsmon will create a file with this name in primary mode when it's
time
>  # to shut down the load.  You should check for this file's existence
in
>  # your shutdown scripts and run 'upsdrvctl shutdown' if it exists,
to tell
>  # the UPS(es) to power off.
> 
Hopefully explained by the above. Also, you don't have to check for the file
directly - you can use "upsmon -K" as in the following excerpt from
the rc.d/nut script in FreeBSD's NUT port:

nut_poststop() {
        if ${nut_prefix}/sbin/upsdrvctl stop && checkyesno nut_upsshut;
then
                if ${nut_prefix}/sbin/upsmon -K; then
                        ${nut_prefix}/sbin/upsdrvctl shutdown
                fi
        fi

}
> 
> 2) LB config.   On a Best Fortress, I can set lowbatt runtime, but only
> 3 digits, even though I want 1800s.   Is this likely a Fortress
> limitation, or a bug?  I will read the source...
Looks like it might be a NUT bug. There should be room for four digits in the
protocol, but the protocol appears to be minutes. NUT shouldn't limit the
seconds field to three characters.
> 2A) seems like nut should be able to have time-based config to start
> shutdown, all of batt%, seconds remaining, and seconds on battery, built
> in.
Others have covered solutions in greater depth (I think Roger's config guide
handles most of these), but IMHO things like "seconds on battery"
aren't as easy as they look (unless you don't care about the
intersection with seconds remaining).
> 3) seems like shutdown should remove /etc/killpower but maybe upsmon
> removes it at boot.  should be explained more, probably, guessing it is
> at boot since fs is ro
probably should be removed at boot (or better yet, placed on a RAM-based
filesystem), but this is not my area of expertise.
> 
> 4) not clear where I should edit in the instant command, as it doesn't
> belong when shutting down upsd, but yet it has to be before.  This is
> complicated.
probably covered by the nut_poststop() example above, but shout if you still
have questions about that.

- Charles

Charles Lepple <clepple at gmail.com> writes:
> On Dec 30, 2022, at 7:42 PM, Greg Troxel <gdt at lexort.com> wrote:
>> 
>> maybe me, maybe docs.
>> 
>> I have never had auto shutdown set up on netbsd.  Mostly I monitor to
>> mqtt.  But now I'm trying and have multiple confusions.
>> 
>> 1) 'upsdrvctl shutdown' vs 'upscmd shutdown.return'
>> 
>> upsdrvctl is about stopping the driver, but lowbatt shutdown wants to
>> send a command.  I don't get the upsmon example file:
>
> "upsdrvctl stop" is for stopping the driver, but "upsdrvctl
shutdown"
> runs "$DRIVER -k" to kill power to the load on the UPS (which is
> actually a second, non-long-running instance of the driver that
> doesn't talk to upsd, after the rest of the system is ready to stop).
>
> That being said, upscmd needs to talk to upsd, which needs a running
> driver - IMHO this is only workable if you trust your
> delay-before-shutdown in the UPS. The "upsdrvctl shutdown" case
can
> often be run after everything has been remounted read-only, at which
> point it is okay if there is no delay before the power gets pulled.
Thanks.  I am editing docs for a soon PR.  Checking my understanding:

psdrvctl stop will not affect the UPS, and upsdrvctl shutdown will spin
up $driver -k, assuming that the previous long-running driver is no
longer running.

And thus one does not use upscmd to do a shutdown, because it needs
upsd/driver running and in getting to fs being ro, those will have been
stopped.

And, one can either:

  do shutdown when upsd/driver/upsmon is stopped and hope delay is long
  enough

or

  have another script that runs essentially last, after the fs are ro,
  so even if no delay it's ok
> Hopefully explained by the above. Also, you don't have to check for the
file directly - you can use "upsmon -K" as in the following excerpt
from the rc.d/nut script in FreeBSD's NUT port:
>
> nut_poststop() {
>         if ${nut_prefix}/sbin/upsdrvctl stop && checkyesno
nut_upsshut; then
>                 if ${nut_prefix}/sbin/upsmon -K; then
>                         ${nut_prefix}/sbin/upsdrvctl shutdown
>                 fi
>         fi
>
> }
got it about -K

This assumes delay, or is that somehow post remount ro?
>> 2) LB config.   On a Best Fortress, I can set lowbatt runtime, but only
>> 3 digits, even though I want 1800s.   Is this likely a Fortress
>> limitation, or a bug?  I will read the source...
>
> Looks like it might be a NUT bug. There should be room for four digits
> in the protocol, but the protocol appears to be minutes. NUT shouldn't
> limit the seconds field to three characters.
Thanks, will read the printed protocol spec I have someplace.
>> 2A) seems like nut should be able to have time-based config to start
>> shutdown, all of batt%, seconds remaining, and seconds on battery,
built
>> in.
>
> Others have covered solutions in greater depth (I think Roger's config
> guide handles most of these), but IMHO things like "seconds on
> battery" aren't as easy as they look (unless you don't care
about the
> intersection with seconds remaining).
Sure, I want:

  if on batt for 2min, start shutdown

and I'm fine with

  if LB, start shutdown

also firing.  Basically one UPS has a desktop (piggy, not important to
stay up, important not to break) and an RPI/switch/wifi (good to keep
running).

I have queued the config examples pdf for reading.
>> 3) seems like shutdown should remove /etc/killpower but maybe upsmon
>> removes it at boot.  should be explained more, probably, guessing it is
>> at boot since fs is ro
>
> probably should be removed at boot (or better yet, placed on a RAM-based
filesystem), but this is not my area of expertise.
/etc is ~never RAM-based, so we need to move to /var/run or equiv, but I
think removing it at startup is easy and maybe already done.  I will
look.