Feature request: publish discovery topics to MQTT regularly or on every reconnect

[ssalonen]

Is your feature request related to a problem? Please describe.

I use openmqttgateway with raspberry pi running mosquitto in volatile/read-only mode. This means that mosquitto and/or restart results in topic contents being lost.

Effectively, after mosquitto/raspberry pi restart the discovery topics are gone.

Since openmqttgateway publishes the discovery topics only once (after restart), the discovery topics will not re-appear in the broker.

Describe the solution you'd like

I would like openmqttgateway either 1) to re-publish discovery topics on re-connect, or 2) re-publish discovery topics regularly (configurable interval similar to SYStoMQTT).

This makes openmqttgateway very robust on any topic data loss on broker end.

Describe alternatives you've considered

As a workaround, I can trigger remote restart of openmqttgateway using MQTT commands topic.

Additional context

The change itself is probably fairly simple. I wanted to open the discussion here whether there is interest towards this change, I can provide PR.

[1technophile]

Hello,

Thanks for proposing this. I think 1) could be interesting in your case.

I'm worried that 2) will lead to missing BLE packets due to the wifi use it will generate.

[ssalonen]

Thanks!

Would it then make sense if I introduce new configurable parameter

• MQTT_PUBLISH_DISCOVERY_ON_CONNECT. Either true or false. Default false.

When MQTT_PUBLISH_DISCOVERY_ON_CONNECT is enabled we would publish discovery information right after successful mqtt reconnect. If it is disabled, we would keep the default behavior of publishing on first connect only.