Custom temperature icon

I have the following sensor:

- platform: rest
  name: Temperature
  scan_interval: 10
  resource: http://xxx.xxx.xxx.xxx?id=21
  json_attributes:
    - Temp
  value_template: >
    {{ value_json['Temp'] | float }}

This works fine, but I want to add a temperature icon. Is this possible? I tried several options, but they seems not to work with a rest platform!

Add this:

device_class: temperature

If that does not add an icon then you will have to use customize.

You should also add a unit_of_measurement to the config if you want to graph the temperature.

Thnx. Yes, indeed in this case that creates a (default) thermometer icon. But I want a specific icon. I tried icon and template_icon, but that did not work. Using customize is a manual task. I like to document my settings so that I can copy/paste the complete configuration.

Then you have to use Customize.

Ok, I will use customize.