Remote power cycling a UPS with HomeAssistant and NUT 🥜 (manually or with an SMS)

By CLN Posted on 15/02/202328/08/2023 Category :

I have a couple of RPI’s running all over the European continent with Home Assistant but most recently I had a couple of devices that became non-responsive.
Normally I use POE switches to power cycle the PoE line and this reboots the device, however in this specific situation, I was out of luck since I’m using a PoE injector after my switch leading to a Pi mounted high on top of a roof for my ADS-B feeder.

my setup is as follows:

so the only option I had left to reboot my roof-mounted RPI3 was either: get a local to power-cycle the PoE injector leading to the roof CAT6 cable.

but then I realized, wait, I have a UPS powering it all, and that UPS is connected (over USB) to an RPI4 in the server rack, why don’t see if I can instruct the RPI4 to power cycle the UPS, and thus would power cycle the RPI3 that’s not responding on the roof.

In my case, I have an APC1500 wired up over a USB

On this page

NUT to the rescue!

The NUT Addon

On the RPI4 I have HomeAssistant running with the Network UPS Tools addon

I’ve configured it as such:

devices:
  - name: APC
    driver: usbhid-ups
    port: auto
    config:
      - vendorid = 051d
mode: netserver
shutdown_host: "false"
users:
  - username: nut
    password: 308KNiwI8zlZgQvx
    instcmds:
      - all
    actions: []
list_usb_devices: true
i_like_to_be_pwned: true

I suggest visiting other sources on how to set up the NUT addon, but long story short: just configure it to the way your UPS is connected to your PI (this can even be a network card)

When I launch the addon my UPS shows up with its vendor ID

Identifying the UPS to send the command to

Before we can send commands to reboot the UPS, we need to figure out what UPS NUT can communicate to, We can do this in 4 ways (for completionist sake I provide other ways) but as we configured the name ourselves, we know the name from the config

The addon config

Check the add-ons config in HA

Checking the NUT addon logs

When checking the NUT addon logs we can see the name of our UPS is APC

Asking the docker container on the list of available UPS’es with the upsc command

by far the easiest way to know what UPS the daemon is configured with/for is by asking it for a list of UPS’es by using upsc

docker exec addon_a0d7b954_nut upsc -l

Checking the /etc/nut/ups.conf

we can request the config of the docker, to figure out the name of the UPS

docker exec addon_a0d7b954_nut tail /etc/nut/ups.conf

check for the name between the square brackets [APC] in this case, so our UPS is named APC

Getting all available commands we can send to our UPS

Now that we know our name, we can query what commands we can send to our UPS

docker exec addon_a0d7b954_nut upscmd -l APC

and there it is, our reboot command

Rebooting a UPS remotely

now knowing our command we can issue our reboot command

NOTE: I have configured a password, so I use it here

docker exec addon_a0d7b954_nut upscmd -u nut -p 308KNiwI8zlZgQvx APC shutdown.reboot

that’s it! you will lose your connection within a few seconds 🤭 whilst the UPS is power-cycling.

Putting the line into a Shell Command (so we can reboot the system much easier)

https://www.home-assistant.io/integrations/shell_command/

# have it as a command
shell_command:
  powercyle_ups: docker exec addon_a0d7b954_nut upscmd -u nut -p 308KNiwI8zlZgQvx APC shutdown.reboot

Rebooting home assistant by SMS/text message

I’ve had cases before where there French Orange router just freezes up, or something is going on that knocks my entire setup offline, so I’ve recently added a GSM modem (~10€) to my setup (official documentation over here)

The modem itself is a USB-a SIM800C

As a last resort, I’ve added the ability to send a text message (send an SMS) to a prepaid number (prepaid sim was ~2.5€ one time fee)

By combining my phone number and the text “reboot” will trigger a UPS power cycle, which will cut the power to all my devices (switches, routers, point-to-point links, etc…)

alias: reboot UPS on sms received 'reboot'
description: Modem received an SMS
trigger:
  - platform: event
    event_type: sms.incoming_sms
condition:
  - condition: template
    value_template: "{{ trigger.event.data.phone == \"+32123456789\" }}"
    alias: my phone number
  - condition: template
    value_template: "{{trigger.event.data.text == \"reboot\" }}"
action:
  - service: shell_command.powercyle_ups
    data: {}
mode: single