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
linkman:nutupsdrv[8].

DESCRIPTION
-----------

This driver, which sits on top of another driver's local UNIX socket file
(or Windows named pipe), 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 linkman:clone[8] driver or linkman:dummy-ups[8] driver running
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 linkman:dummy-ups[8] generally, 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 linkman: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 linkman: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 linkman: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 linkman:upsmon[8] primary sees the OB LB flags and tells the
linkman:upsd[8] 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 its 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 an `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.

//////////////////////////////////////
TODO later: declare the driver as "optional", see
https://github.com/networkupstools/nut/issues/1389
//////////////////////////////////////

AUTHOR
------

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

SEE ALSO
--------

linkman:upscmd[8],
linkman:upsrw[8],
linkman:ups.conf[5],
linkman:clone[8],
linkman:nutupsdrv[8]

Dummy driver:
~~~~~~~~~~~~~

The "repeater" mode of 'dummy-ups' driver is in some ways similar to the
'clone' and 'clone-outlet' drivers, by relaying information from a locally
or remotely running "real" device driver (and NUT data server).

linkman:dummy-ups[8]

Internet Resources:
~~~~~~~~~~~~~~~~~~~

The NUT (Network UPS Tools) home page: https://www.networkupstools.org/
