A simple script to control the Elgato Key Light

el.sh

#!/usr/bin/env zsh

set -e
set -u
set -o pipefail

WIFI=$(nmcli -t -f active,ssid dev wifi | grep '^yes' | cut -d':' -f2)
if [[ "${WIFI}" != "WTF" ]]; then
  echo "Not in the office, WiFi network ${WIFI}"
  exit 0
fi

# Use "avahi-browse -arplt" to list & resolve devices on your local
# network.
HOSTNAME=elgato-key-light-4853.local

URL="http://${HOSTNAME}:9123/elgato/lights"
TIMEOUT=5

# What to do by default
on_or_off=1
brightness=15
temperature=249

# Parse arguments and update what to do
while [[ "$#" -gt 0 ]]; do
  case $1 in
    # One-off & exit
    s|status) curl "${URL}" --header "Accept: application/json" --max-time ${TIMEOUT}; exit 0 ;;

    # Tweak parameters
    1|on) on_or_off=1 ;;
    0|off) on_or_off=0 ;;
    -b|--brightness) brightness="$2"; shift ;;
    -t|--temperature) temperature="$2"; shift ;;
    *) echo "No idea: $1"; exit 1 ;;
  esac
  shift
done

# State looks like this:
#
# {"numberOfLights":1,"lights":[{"on":0,"brightness":66,"temperature":222}]}
#
# on = 0|1
# brightness = 0..100
# temperature = 143 - 344  (divide by 0.05 to get it in Kelvins)

# Get it -> modify it -> put it back
curl -s "${URL}" --header "Accept: application/json" --max-time ${TIMEOUT} |
  jq ".lights[] |= (.on = $on_or_off | .brightness = $brightness | .temperature = $temperature)" |
  curl -s -X PUT "${URL}" --header "Accept: application/json" -d @- -o /dev/null --max-time ${TIMEOUT}