Help getting REST working - noob to HA

I am new to HA but have been using Universal Devices controller with Insteon for years.
I could sent a REST command from a Pi java program to the UD to turn on a light, get status, etc.
Ex: http://192.168.1.185/rest/nodes/24%2076%205C%201/cmd/DON ← turns on a light.

I want to Duplicate this functionality with HA. I want to update my existing Java GUI to work with HA.
So far the documentation and examples have not helped me.
I need a simple example like turning on a light, step by step.
Where can I find this?

Do I have to create or edit a xxx.yaml file?
How do I http to it from another Pi?

https://www.home-assistant.io/integrations/rest_command/#examples

Yes

By creating a rest command as per the example, then calling that command from an automation or button tap action.

I placed the following in configuration.yaml - it does not do anything in the developer tools.

Next, I entered the following in a chrome on my windows PC
http://192.168.1.57:8123/turn_light_on
I got – 404: Not Found

I have an automation routine that does work when a switch is toggled.
I need the action portion to work with the above REST configuration.
What has to be changed? I am not getting it yet. One working configuration should help me a lot.

alias: Bonus Room Rear Light On
description: “”
trigger:

  • platform: state
    entity_id:
    • switch.rear_light_button
      condition:
  • condition: state
    entity_id: switch.rear_light_button
    state: “on”
    action:
  • type: turn_on
    device_id: dc74e3efae728b34ce5355f34fc3a195
    entity_id: light.bonus_room_rear
    domain: light
    mode: single

Slightly off topic but there is a full integration to Insteon through the Hub or PLM that you must be using (i.e. skip the Universal Devices controller). Or there is probably one for the controller too. There is no need to write REST commands to do this.

Yes, I have an ISY994i. My Pi display that I created does REST commands to it. However, I have added some LED WiFi bulbs. I believe UDI will not handle them directly. I would need Polyglot. So I investigated HA and going forward, I feel that HA & UDI is better that UDI and Polyglot. But I am only (2) days into HA.

Did you try just adding the ISY994 integration in Home Assistant? See Universal Devices ISY994 - Home Assistant

It should read most all the devices right in the ISY.

But then I missed the point I guess … it looks like you want to use your existing GUI and not do something in Lovelace,

Yes, That is what I am doing. HA and ISY are working great together.
You are correct, I want my existing GUI. I have a flashing LED when the garage door is open. A blue one when we forgot to turn off certain devices.
I don’t have to keep checking a program to see status. This is in my office.
I also use ISY to text me critical messages.

OK, I would go above and edit your post and use the </> to enter the YAML code in. No one can even start to diagnose as YAML depends on indentation and types and it cannot be see unless you paste code in as code and not as text. Then we can start to assist you for a good example.

Or perhaps this is what you want via webhook:

Which would lead you here:

OK, what do you have in mind?

I try the following from examples using my token and the IP for the Pi running HA from my PC on the same network.
I get 401: Unauthorized.

curl -X GET -H “Authorization: Bearer ABCDEFGH”
-H “Content-Type: application/json” http://localhost:8123/api/states

If you are running that curl to localhost from your PC you are not addressing your Pi, you need the Pi IP address in the curl.
Also make sure you align your http,s with use of SSL on your Pi

I finally have everything working. It was a simple problem that was hard to find. When I created the token, I double clicked in the box and did a copy and paste. It appeared to capture the entire token, however, double clicking only got part of it. You can not drag to select the text. triple clicking, does select the entire text. Once I had a valid token, everything started working.

It now works great.