MQTT is a PUB/SUB protocol for the Internet of Things, but it's also valuable for systems administration. We'll take a close look at MQTT and its infrastructure, and we'll show you how to use a microcontroller to monitor your server-room's temperature with it, publishing and monitoring it via MQTT and Icinga/Nagios

1. MQTT
for monitoring (and for the IoT)
Jan-Piet Mens
November 2014
@jpmens

2. MQTT is a standard,
a transport,
PUB/SUB messaging,
designed for
unreliable networks

3. transport protocol
binary payload, 256MB, (+2 bytes),
fast,
lightweight, ideal for low-bandwith,
high-latency networks

4. security
TLS
authentication
ACLs
TLS-PSK
(payload encryption)

5. Quality of Service
0 At most once
1 Assured delivery
2 Once only

6. more features
keepalive
last will & testament,
decoupled senders/recipients,
durable messages

7. topic names
UTF-8, hierarchical, wildcards
temperature/room/living
devices/#
finance/+/eur/rate

8. PUB/SUB cauldron

9. MQTT brokers
the server bit of MQTT

10. Mosquitto
C, fast, lightweight, ACLs (plugin), TLS, TLS-PSK, bridge,
Websockets, logging via $SYS
http://mosquitto.org

11. HiveMQ
Java, plugins, Websockets, clustering, modules
http://hivemq.com

12. MQTT brokers
$SYS topic
$SYS/broker/clients/total 1771
$SYS/broker/messages/received 36597465
$SYS/broker/messages/sent 39714120
$SYS/broker/messages/stored 2941
$SYS/broker/bytes/received 2830787008
$SYS/broker/bytes/sent 3810653433
$SYS/broker/version mosquitto version 1.4
$SYS/broker/publish/messages/received 19798673
$SYS/broker/publish/messages/sent 30622855
$SYS/broker/publish/bytes/received 1868229299
$SYS/broker/publish/bytes/sent 3185942282

13. bridging

14. CLI utilities
mosquitto_sub -v
[-h localhost] [-p 1883]
[--cafile file]
[--cert file --key file]
[-u username [-P password]]
[ --tls-version tlsv1.2 ]
-t 'topic/#'
subscribe
publish
mosquitto_pub
...
[-r]
-t topic
-m payload

15. languages
Lua, Python, C, JavaScript, Perl, Ruby, Java, ...

16. Python API: PUB
#!/usr/bin/env python
import paho.mqtt.publish as mqtt
mqtt.single('conf/hello', 'Hello MQTT')
topic payload
$ mosquitto_sub -h localhost -v -t 'conf/#'
conf/hello Hello MQTT

17. Python API: SUB
callbacks
#!/usr/bin/env python
import paho.mqtt.client as paho
def on_connect(mosq, userdata, rc):
mqttc.subscribe("conf/+", 0)
def on_message(mosq, userdata, msg):
print "%s %s %s" % (msg.topic, str(msg.payload), userdata)
data = { 'type' : 'conference' }
mqttc = paho.Client(userdata=data)
mqttc.on_connect = on_connect
mqttc.on_message = on_message
mqttc.connect("localhost", 1883, 60)
mqttc.loop_forever()

18. Python API: SUB
$ mosquitto_pub -t 'conf/thirsty' -m 'Beertime?'
$ mosquitto_pub -t 'conf/catering' -m 'Coffee is ready'
$ ./sub.py
conf/thirsty Beertime? {'type': 'conference'}
conf/catering Coffee is ready {'type': 'conference'}

19. practical solutions
alerting, metering, logging, location awareness, tracking,
automation, and controlling, host monitoring

20. alerting: mqttwarn
https://github.com/jpmens/mqttwarn

21. temperature: Arduino
huh?

22. all good!

23. how does this work?
arduino/10.0.69.105/celsius 24

24. critical: not good!

25. via MQTT to mobile

26. mqtt.org
@mqttorg