CLONE-OUTLET(8)

NAME

clone-outlet - clone an UPS, treating its outlet as if it were an UPS (monitoring only)

SYNOPSIS

clone-outlet -h

clone-outlet -a UPS_NAME [OPTIONS]

Note	This man page only documents the specific features of the clone-outlet driver. For information about the core driver, see nutupsdrv(8).

DESCRIPTION

This driver, which sits on top of another driver socket, allows users to group clients to a particular outlet of a device and deal with this output as if it were a normal UPS. Unlike the clone(8) driver or dummy-ups(8) in repeater mode, this driver represents a read-only device for monitoring and shutdowns (it does not accept setting any values or sending instant commands during run time).

Unlike dummy-ups(8), this driver does not require a running upsd data server nor use the networked NUT protocol to talk to the "real" driver (which may be remote in case of dummy-ups repeater mode).

This driver does not create a completely new virtual device, but replaces or extends some of the original readings reported by the "real" driver using information from the specified outlet, and relays all other readings as they were.

Remote clients like upsmon can MONITOR the device entry presented by the data server with this driver (and the "real" driver) running and published.

A larger deployment with one or more lower-priority devices collected on a manageable outlet of an UPS or ePDU would likely see several drivers set up on the system actually capable of interactions with the UPS and running the NUT data server upsd(8) (and likely powered by another outlet):

a "real" driver talking to the UPS;
a clone driver talking to the "real" driver and issuing outlet power-off (or power-cycle) based on relatively high thresholds for remaining battery charge and/or runtime of the actual UPS (or explicit instant commands), with such operations first setting the respective timers for the outlet on the "real" driver, and the "FSD" flag among states of the virtual UPS status;
possibly a clone-outlet driver which is read-only and interprets the outlet timer values as triggers for "FSD" or "OFF" flags reported among states of the virtual UPS status.

With this approach, the lower-priority systems collected on such outlet would run the NUT upsmon(8) client to MONITOR the virtual UPS presented by the read-only clone-outlet driver and shut down as soon as the "FSD" flag is raised (fairly early, based on charge and/or runtime thresholds configured for that driver) allowing the higher-priority devices (likely including the NUT server) to enjoy a longer on-battery life.

The clone driver responsible for outlet power state changes would not normally be monitored directly (e.g. to avoid unfortunate direct shutdown requests from those clients), although it can be (instead of clone-outlet) in sufficiently trusted networks.

EXTRA ARGUMENTS

This driver supports the following settings:

port=drivername-devicename: Required. The standard NUT driver port setting, here it provides the name of the local Unix socket (or named Windows pipe) for connection to the "real" driver.
prefix=outlet.N: Required. Specify the outlet prefix as known on the original driver. The subset of data points reported by the "real" UPS driver for the actual device on this prefix would be reported as data points of the virtual UPS maintained by this driver.

IMPLEMENTATION

The port specification in the ups.conf(5) should reference the local driver socket (or Windows named pipe) that the "real" UPS driver is using. For example:

  [realups]
     driver = usbhid-ups
     port = auto

  [clone-outlet-1]
     driver = clone-outlet
     port = usbhid-ups-realups
     prefix = outlet.1
     desc = "Outlet 1 of the Real UPS"
     [...]

The driver internally interprets "real" driver’s information about shutdown delay and shutdown timer, whole UPS status and this outlet’s status, and relays other data points as they were.

If the outlet supports and reports a delayed power-off, the virtual UPS would issue an FSD via ups.status for its clients to shut down safely.

In more detail:

Given the (required) prefix value such as outlet.1, the driver would specifically keep track of <prefix>.status, <prefix>.delay.shutdown, and <prefix>.timer.shutdown data points reported by the "real" driver. Numeric values of the *.shutdown readings would be noted by this driver, and the boolean outlet status ("off" or otherwise) will be remembered. These values will also be re-published by this driver "as is".

The ups.status from the "real" driver would be remembered, but not re-published by this driver immediately. Instead, it would be published during regular "update info" loop cycles either:

with the "OFF" state added (if <prefix>.status indicates the outlet is "off"),
or with the "FSD" state prepended (if <prefix>.timer.shutdown is non-negative and does not exceed the <prefix>.delay.shutdown value),
or "as is" if the outlet power state is "not critical".

IMPORTANT

Unlike a real UPS, you should not configure a upsmon primary mode for this driver. When a upsmon primary sees the OB LB flags and tells the upsd server it is OK to initiate the shutdown sequence, the server will latch the FSD status and it will not be possible to restart the systems connected without restarting the upsd server.

This will be a problem if the power returns after the clone UPS initiated the shutdown sequence on it’s outlet, but returns before the real UPS begins shutting down. The solution is in the clone driver, that will insert the FSD flag if needed without the help of a upsmon primary.

CAVEATS

The clone UPS will follow the status on the real UPS driver. You can only make the clone UPS shutdown earlier than the real UPS driver, not later. If the real UPS driver initiates a shutdown, the clone-outlet UPS driver will immediately follow.

Be aware that the commands to shutdown/restart an outlet on the real UPS drivers are not affected, so if you tell the real UPS driver to shutdown the outlet of the clone UPS driver immediately, your clients will lose power without warning. A delayed outlet power-off should propagate as FSD, and the delay should be sufficiently long to allow for client shutdowns.

If you use service management frameworks like systemd or SMF to manage the dependencies between driver instances and other units, then you may have to set up special dependencies (e.g. with systemd "drop-in" snippet files) to queue your clone drivers to start after the "real" device drivers.

AUTHOR

Arjen de Korte <adkorte-guest@alioth.debian.org>