MQTT-based voltage daemon built on Network UPS Tools

voltage_ha_logger.sh

#!/bin/bash 

#set -eu

ha_prefix="homeassistant"
ha_config_suffix="config"
ha_state_suffix="state"
ha_component="sensor"
ha_object_id="ac_voltage_meter_powercom"
ha_common_prefix=$ha_prefix/$ha_component/$ha_object_id
ha_config_topic=$ha_common_prefix/$ha_config_suffix
ha_state_topic=$ha_common_prefix/$ha_state_suffix
ha_config=$(cat <<JSON
{
    "name": "AC Input Voltage",
    "unique_id": "$ha_object_id",
    "state_topic": "$ha_state_topic",
    "device_class": "voltage",
    "state_class": "measurement",
    "unit_of_measurement": "V"
}
JSON
)

echo Using config topic: $ha_config_topic
echo "Using config: $ha_config"

mosquitto_pub -r -t "$ha_config_topic" -m "$ha_config"

previous_voltage=-1

while true
do
    upsinfo=$(upsc powercom 2>/dev/null |grep 'input.voltage:')
    voltage=${upsinfo#input.voltage: }
    voltage=${voltage%.0}

    if [ $voltage != $previous_voltage ]
    then
        echo "Publishing $voltage"
        mosquitto_pub -t $ha_state_topic -m $voltage
        previous_voltage=$voltage
    fi

    sleep 1
done

Logger for Home Assistant:

Requires:

1. UPS with data channel
2. Network UPS Tools (NUT)
3. Eclipse Mosquitto MQTT Brocker