LWT on child broker

[agrosjea]

Hi ! I am enountering an issue on Mosquitto using a dual broker configuration main broker in the cloud is 1.5.5 (cant update right now) client broker is 1.5.7 under Windows with the following conf file :

port 1883
protocol mqtt
connection_messages true
log_timestamp true
log_type warning
log_dest file c:\mqtt_log.log

connection MyServer
address myserver:1883
topic # both 1
clientid MyClientBroker

• Connexion works as expected and my Windows client can both publish and retrieve messages from main server.
• Using MQTT box I connect a client (using TCP/MQTT protocol) and define Last Will Testament QoS 2 and retained.
• Whenever I disconnect manually my MQTT box client, I can see that the LWT is handled when I reconnect.
• But if I stop my service in Windows abruptly, the last will is not handled by the main server. Is that a bug or is it as designed ? Any workaround ?

A possible workaround for me would be to be able to define an Will message for the Windows broker itself. But I do not see any mention in the config file on how to define a Will.

[vincent-boulin]

Hello,

I'll let more experienced people confirmed what i say but it seem this is already corrected : #1143. If you look the changelog of the 1.5.6 version this issue is mentionned.

[agrosjea]

Hi ! The issue you referenced was on websocket only. I used TCP/MQTT protocol here. I can update my server to 1.5.7 just to ensure I can reproduce with 1.5.7 both sides...

[agrosjea]

I installed 1.5.8 on my server I confirm: -CASE 1 : whenever im connected to my local broker with my client and disconnect my client in a clean way from the broker. the LWT message is send by the broker -CASE 2 : if I kill my local broker, the LWT message is not handled by the remote broker.

I will create another issue to be able to set an LWT message when Mosquitto 1.5.7 connects to 1.5.8 which could do the trick I think...

[ckrey]

The bridge protocol (between your "Mosquitto 1.5.7" and "Mosquitto 1.5.8") does not support LWTs other than forwarding the LWTs of the clients.

This means what you see is how it was designed.

If you want to monitor the status of your bridge between the to brokers, please consider to use notification messages in mosquitto.conf:

# Choose the topic on which notification messages for this bridge are
# published. If not set, messages are published on the topic
# $SYS/broker/connection/<clientid>/state
#notification_topic

Can this issue be closed?