Fix missing MQTT QoS initialization to enable QoS 1 and 2

[lglenat]

Changing the QOS setting in the toml config file currently does not have any effect on the actual QoS used by the MQTT backend.
It seems that there has been a regression a while ago during a major refactoring of the architecture.

I am not sure this is the best way of fixing the issue, but it does the job. As for testing, with this fix I was able to have the gateway bridge connected with QoS 1 to AWS IoT.

[lglenat]

I don't know if it would be better to have this in the Backend instantiation at line 87. Feel free to amend.

[brocaar]

Good catch! I have moved this line to the struct initialization :-)

[tomasol]

Hello, this seems not to be fixed i 2.6.2. I can change qos when placing into deprecated [backend.mqtt], but it does not work for [backend.mqtt.auth] mentioned in the documentation.

[lglenat]

Hello, this seems not to be fixed i 2.6.2. I can change qos when placing into deprecated [backend.mqtt], but it does not work for [backend.mqtt.auth] mentioned in the documentation.

Are you sure? I tested today with the latest version and qos = 1 in [backend.mqtt.auth.generic] and it was working fine (see output logs below):

...
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
INFO[0049] mqtt: publishing message qos=1 topic=gateway/647fdxxx
...

[tomasol]

I found that the problem only occurs when using marshaler="v2_json" . If that's the case, root_run.go#runV2 gets called and qos is read only from the old location [backend.mqtt]. If runV3 is activated, old and new location [backend.mqtt.auth.generic] can be used.
This should be highlighted in the documentation or at least made consistent - current documentation uses old marshaller and new qos location.