mqtt-hs for an MQTT server about mqtt-hs

[dustin]

All of my mqtt services are currently using https://github.com/dustin/mqttd which is, as far as I can tell, more feature-complete than mosquitto. I had a few bugs with mosquitto that were bothering me, so I also wanted to see what it'd take to write such a thing. :)

I'm not entirely sure how adaptable that is. Perhaps it'd be possible to extract the state management. This is an area I'm not super familiar with. My code currently manages its data structures with STM and persist state with SQLite. It'd probably be possible to abstract the SQLite bits.

[cdupont]

That's great!! I didn't find it last time I looked for an MQTT broker in Haskell. Can it be put on Hackage?

[dustin]

I'm not opposed to the idea. https://hackage.haskell.org/package/mqttd isn't taken. I think of it more as a program than anything, so it seems a bit odd to me. It'd be fantastic if someone else could benefit from the service, though.

24 hours of my home mqttd on an Orange Pi looks like this:

Fairly normal stuff. "actions" is mainly timed tasks for stuff like expiring sessions or retained messages (I use MQTT v5 retention timeouts a lot). "influx spool" is how much junk influxer has read and written to disk waiting for connectivity to return so it can stick it in a remote influxdb.

Are you able to try it without hackage and see if it looks remotely useful? It'd be good to get any obvious stuff fixed up before it publishing it. I've been relying on it for around a year now and have had fewer problems than I did with mosquitto. :)

Worth noting that it doesn't have built-in replication. I don't see that as a useful thing as mosquitto's built-in replication also didn't work well for me, so I wrote mqtt-bridge to handle that. Specifically, it properly bridges mqtt v5 properties including remaining expiration time on retained items.

[dustin]

I'll go ahead and close this since there's a working solution. Please let me know on https://github.com/dustin/mqttd if there's anything that can make that more useful.

(I've got two open issues that are there for theoretical correctness, but don't affect me)