MQTT discovery retain or not for addons

Configuration
1

Hi,

there are only old topics about retain flag in MQTT discovery.
They didn’t answer my question.

I am developing an addon (GitHub - modbus2mqtt/hassio-addon-repository: Repository for Home Assistant Addon Modbus <=> MQTT) which supports MQTT discovery.

When homeassistant starts, it will also be started.
During initialization, it will send discovery messages.
So, is there really a need to set the retain flag?
If the addon doesn’t set the retain flag, it’s much easier to delete unavailable entities.

What do you think?
What is the benefit of setting the retain flag, if the addon anyhow sends mqtt discovery for the devices available for the addon?

Thank you,

Volkmar

2

If you restart HA only (not HAOS), all your entities will disappear, because the discovery topics will be gone.

3

Thank you. This is an good explanation