Map json prop as labels

[v0l]

Hi,

It would be nice to be able to map some properties as labels to help identify devices which publish to a single topic.

I have a use case with rtl_433 which is collecting weather station data into a single topic at rtl_433/{hostname}/events

Here is an example json:

{
   "time":"2021-11-11 14:18:45",
   "model":"Fineoffset-WHx080",
   "subtype":0,
   "id":196,
   "battery_ok":1,
   "temperature_C":13.1,
   "humidity":90,
   "wind_dir_deg":135,
   "wind_avg_km_h":1.224,
   "wind_max_km_h":3.672,
   "rain_mm":58.5,
   "mic":"CRC"
}

It would be useful to be able to map id or model to labels to help identify the device event.

- prom_name: temperature
  mqtt_name: temperature_C
  type: gauge
  labels:
  - model
  - id
  - subtype

[hikhvar]

I can relate to that use case. I welcome a PR adding this functionality. If I have enough spare time, I may implement it myself, but I can not give any time estimates on that.

[v0l]

I don't have much experience with Go but I can try to give it a shot if I get a chance..