FlashMQ stops publishing unless keepalive is received — usability and integration concern

[mti-sk]

Description:

In VenusOS v3.20 and later, the MQTT broker implemented via dbus-flashmq stops publishing data unless a keepalive message is received in the topic R/<vrm_instance>/keepalive. While this behavior may be intended to reduce unnecessary traffic, it introduces significant usability and integration issues:

• It breaks compatibility with existing MQTT clients and integrations (e.g. Home Assistant, Node-RED) that expect passive data flow.
• The requirement to send keepalive to the VRM instance topic — not just any client ID — is undocumented and non-obvious.
• The configuration file /etc/flashmq/flashmq.conf does not offer an option to disable or modify this behavior.
• Many users expect that subscribing to topics is sufficient to receive updates, as was the case in earlier VenusOS versions.

Alternative workaround:

It appears that publishing any message to the broker — even outside the keepalive topic — can bypass the keepalive requirement and resume data flow. This workaround is undocumented and fragile.

Suggestions:

Please consider one or more of the following improvements:

• Add a configuration option in /etc/flashmq/flashmq.conf to disable the keepalive requirement.
• Allow publishing to continue if any client is actively subscribed.
• Document this behavior clearly in the VenusOS and dbus-flashmq wiki.

This change has caused confusion and broken setups for many users. A more flexible or transparent approach would be greatly appreciated.

Thanks for your work!