Change Icon color of light.A, based on availability of light.B

Configuration
1

I’m quite new with Hassio.

I would like to change the color of a light icon “ingresso” when the status of a second light “status ingresso” changes.
I was able to send a telegram message, with an automation as on the following configuration

configuration file …

  • platform: mqtt
    name: “ingresso”
    command_topic: “cmnd/corridoio1-3/power”
    state_topic: “stat/corridoio1-3/POWER”
    payload_on: “ON”
    payload_off: “OFF”
    availability_topic: “tele/corridoio1-3/LWT”
    payload_available: “Online”
    payload_not_available: “Offline”
    qos: 1
    retain: false

  • platform: mqtt
    name: “status ingresso”
    command_topic: “cmnd/corridoio1/status/power”
    state_topic: “stat/corridoio1/status/POWER”
    payload_on: “ON”
    payload_off: “OFF”
    availability_topic: “tele/corridoio1/status/LWT”
    payload_available: “Online”
    payload_not_available: “Offline”
    qos: 1
    retain: false

Automation file …

  • id: icona luce ingresso
    alias: Telegram icona luce ingresso
    trigger:
  • entity_id: light.status_ingresso
    from: ‘unavailable’
    platform: state
    to: ‘off’
    action:
  • data:
    message: Allarme accensione in ingresso
    title: Accensione ingresso
    service: notify.telegram_bot

but I don’t know how to set up the icon color change of a light (ingresso) on the automation action section, when the availability of another light (status ingresso) changes.

I tried to add this configuration fragment to configuration.yaml, but it does not work:

customize:

 light.ingresso:
  templates:
    icon_color: >
      if (light.status_ingresso.state === 'unavailable') return 'rgb(0, 0, 255)';  
      return 'rgb(255, 0, 0)';

Please note these are the 2 states:

  1. [light.status_ingresso] unavailable
  2. [light.status_ingresso] off

Anybody can help me ? Thank You very much in advance.