zigbee2mqtt should remove 'retained' value from broker on device rename

[sjorge]

Bug Report

What happened

I was testing an new temp/humidity sensor (sonoff) as I was not happy with my current TuYa one.

So I had 2:

• bedroom/sensor (TuYa)
• bedroom_aux/sensor (SONOFF)

I was happy with the SONOFF so I decided to replace the TuYa one.

1. renamed bedroom/sensor to bedroom_old/sensor
2. renamed bedroom_aux/sensor to bedroom/sensor

I however noticed node-red and some other mqtt clients still saw retained values for bedroom_aux/sensor being published on connect.

2020/09/06 16:51:31 INFO     mqtt2rrd: received 'zigbee2mqtt/bedroom_aux/sensor' with '{'temperature': 20.59, 'humidity': 55.82, 'linkquality': 60, 'battery': 100}'

I did some digging to verify it is indeed only the retained value still present on the broker.

What did you expect to happen

I'd expect zigbee2mqtt to tell the broker to forgot the old retained value on rename (or on device removal too actually)

How to reproduce it (minimal and precise)

• mosquitto broker with retain configured to be perstistantly stored on disk
• z2m connect to mosquitto
• other client connected to mosquitto subscribed to the z2m topics.

Debug Info

[root@amethyst /opt/zigbee2mqtt]# mosquitto_sub -t zigbee2mqtt/bridge/info | jq .coordinator
{
  "meta": {
    "maintrel": 3,
    "majorrel": 2,
    "minorrel": 6,
    "product": 0,
    "revision": 20200728,
    "transportrev": 2
  },
  "type": "zStack12"
}

[sjorge]

I got an easier test to show the retained value! You can just use mosquitto_sub to get it.

[root@amethyst /opt/zigbee2mqtt]# mosquitto_sub -t zigbee2mqtt/bedroom_aux/sensor
{"battery":100,"humidity":55.82,"linkquality":60,"temperature":20.59,"voltage":3200}

[Koenkk]

Implemented! Will only be done when renaming through the new api.

Changes will be available in the latest dev branch in a few hours (https://www.zigbee2mqtt.io/how_tos/how-to-switch-to-dev-branch.html)

[sjorge]

👍