Dynamic WatchDog MQTT

General
1

Hello Community,

I use MQTT protocol for my system.I have a lot of rpi and I use a dynamic post but the properties WagDog is not dynamic.

WatchDog
WatchDog652×894 68.1 KB

Ex:
rpi 1 the topic is RPI1/Input
RPI1/Watchdog
rpi 2 the topic is RPI2/Input
RPI2/Watchdog
...
...
...
rpi X the topic is RPIX/Input
RPIX/Watchdog

Is it possible to make this properties dynamic?

Thank you

2

Most aspects of the MQTT nodes are dynamic (including setting LWT) however you don't really need that complexity.

Just use env vars instead.

E.g. ${MQTTLWT}

https://nodered.org/docs/user-guide/environment-variables

3

Ok I understand the principle but not the method of writing.

Could I have an example of flow?

4

Um. Not really practical TBH.

Here is a minimal procedure:

  • set an environment variable named MQTTLWT to the value RPI1/Watchdog in PI 1
  • set an environment variable named MQTTLWT to the value RPI2/Watchdog in PI 2
  • set an environment variable named MQTTLWT to the value RPIn/Watchdog in PI n
  • change the MQTT config "Messages" topics from RPI1/Watchdog to ${MQTTLWT}
  • (re)start node-red on all the PIs

As for how to set an env variable - this is an operating system specific thing (but there are LOTS of docs, tutorials and vides around the net - just search "set permanent environment variable debian")