For several years now the OSMC has been extended by one day in the form of a “hackathon”. As I do not consider myself a developer I usually skip this day, but since I wanted to spend more time with Ronny Trommer and to explore the OpenNMS MQTT plugin, I decided to attend this year.

I’m glad I did, especially because the table where we sat was also home to Dave Kempe, and he brought Tim Tams from Australia:

Yum.

You can find them in the US on occasion, but they aren’t as good.

I have been hearing about MQTT for several years now. According to Wikipedia, MQTT (Message Queuing Telemetry Transport) is a messaging protocol designed for connections with remote locations where a “small code footprint” is required or the network bandwidth is limited, thus making it useful for IoT devices.

Dr. Craig Gallen has been working on a plugin to allow OpenNMS to consume MQTT messages, and I was eager to try it out. First, we needed a MQTT broker.

I found that the OpenHAB project supports an MQTT broker called Mosquitto, so we decided to go with that. This immediately created a discussion about the differences between OpenHAB and Home Assistant, the latter being a favorite of Dave. They looked comparable, but we decided to stick with OpenHAB because a) I already had an instance installed on a Raspberry Pi, and b) it is written in Java, which is probably why others prefer Home Assistant.

Ronny worked on getting the MQTT plugin installed while I created a dummy sensor in OpenHAB called “Gas”.

This involved creating a “sitemap” in /etc/openhab2:

sitemap opennms label="My home automation" {
    Frame label="Date" {
        Text item=Date
    }
    Frame label="Gas" {
        Text item=mqtt_kitchen_gas icon="gas"
    }
}

and then an item that we could manipulate with MQTT:

Number mqtt_kitchen_gas "Gas Level [%.1f]" {mqtt="<[mosquitto:Home/Floor1/Kitchen/Gas_Sensor:state:default]"}

To install the MQTT plugin:

• Create folder deploy in ${OPENNMS_HOME}
• Download the KAR file or compile it from source and drop it to the deploy folder.
• Create a mqtt-interface-config.xml file

Ronny added the following to the configuration to connect to our Mosquitto broker on OpenHAB:

<mqttclients>
  <client clientinstanceid="client1">
    <brokerurl>tcp://172.20.11.8:1883</brokerurl>
    <clientid>opennms</clientid>
   <connectionretryinterval>3000</connectionretryinterval>
    <clientconnectionmaxwait>20000</clientconnectionmaxwait>
    <topiclist>
      <topic qos="0" topic="iot/#">
    </topic>
    <username>openhabian</username>
    <password>openhabian</password>
    </client>
</mqttClients>

Now that we had a connection between our OpenHAB Mosquitto broker and OpenNMS, we could try to send information. The MQTT plugin handles both event information and data collection. To test both we used the mosquitto_pub command on the CLI.

For an event one can use something like this:

#/bin/bash
mosquitto_pub -u openhabian --pw openhabian -t "iot/timtam" -m "{ \"name\": \"6114163\",  \"sensordatavalues\": [ { \"value_type\": \"Gas\", \"value\": \"$RANDOM\"  } ] }"

On the OpenNMS side you need to configure the MQTT plugin to look for it:

<messageEventParsers>
  <messageEventParser foreignSource="$topicLevels[5]" payloadType="JSON" compression="UNCOMPRESSED">
    <subscriptionTopics>
      <topic>iot/timtam/event/kitchen/mysensor/doorlock</topic>
    </subscriptionTopics>

    <xml-groups xmlns="http://xmlns.opennms.org/xsd/config/xml-datacollection">
      <xml-group name="timtam-mqtt-lab" resource-type="sensors" resource-xpath="/" key-xpath="@name">
        <xml-object name="instanceResourceID" type="string" xpath="@name"/>
        <xml-object name="gas" type="gauge" xpath="sensordatavalues[@value_type="Gas"]/value"/>
      </xml-group>
    </xml-groups>
    <ueiRoot>uei.opennms.org/plugin/MqttReceiver/timtam/kitchen
  </messageEventParser>
</messageEventParsers>

Note how Ronny worked our Tim Tam obsession into the configuration.

To make this useful, you would want to configure an event definition for the event with the Unique Event Identifier (UEI) of uei.opennms.org/plugin/MqttReceiver/timtam/kitchen:

<events xmlns="http://xmlns.opennms.org/xsd/eventconf">
  <event>
    <uei>uei.opennms.org/plugin/MqttReceiver/timtam/kitchen</uei>
    <event-label>MQTT: Timtam kitchen lab event</event-label>
    <descr>This is our Timtam kitchen lab event</descr>
    <logmsg dest="logndisplay">
      All the parameters: %parm[all]%
    </logmsg>
    <severity>Normal</severity>
    <alarm-data reduction-key="%uei%:%dpname%:%nodeid%:%interface%:%service%" alarm-type="1" auto-clean="false"/>
  </event>
</events>

Once we had that working, the next step was to use the MQTT plugin to collect performance data from the messages. We used this script:

#!/bin/bash
while [ true ]
do
mosquitto_pub -u openhabian --pw openhabian -t "Home/Floor1/Kitchen/Gas_Sensor" -m "{ \"name\": \"6114163\",  \"sensordatavalues\": [ { \"value_type\": \"Gas\", \"value\": \"$RANDOM\"  } ] }"
sleep 10
done

This will create a message including a random number every ten seconds.

To have OpenNMS look for it, the MQTT configuration is:

<messageDataParsers>
  <messageDataParser foreignSource="$topicLevels[5]" payloadType="JSON" compression="UNCOMPRESSED">
    <subscriptionTopics>
      <topic>iot/timtam/metric/kitchen/mysensor/gas</topic>
    </subscriptionTopics>
    <xml-groups xmlns="http://xmlns.opennms.org/xsd/config/xml-datacollection">
      <xml-group name="timtam-kitchen-sensor" resource-type="sensors" resource-xpath="/" key-xpath="@name">
        <xml-object name="instanceResourceID" type="string" xpath="@name" />
        <xml-object name="gas" type="gauge" xpath="sensordatavalues[@value_type="Gas"]/value"/>
      </xml-group>
    </xml-groups>
    <xmlRrd step="10">
      <rra>RRA:AVERAGE:0.5:1:20160</rra>
      <rra>RRA:AVERAGE:0.5:12:14880</rra>
      <rra>RRA:AVERAGE:0.5:288:3660</rra>
      <rra>RRA:MAX:0.5:288:3660</rra>
      <rra>RRA:MIN:0.5:288:3660</rra>
    </xmlRrd>
  </messageDataParser>
</messageDataParsers>

This will store the values in an RRD file which can then be graphed within OpenNMS or through Grafana with the Helm plugin.

It was pretty straightforward to get the OpenNMS MQTT plugin working. While I’ve focused mainly on what was accomplished, it was a lot of fun chatting with others at our table and in the room. As usual, Netways did a great job with organization and I think everyone had fun.

Plus, I got to be reminded of all the amazing stuff being done by the OpenNMS team, and how the view is great up here while standing on the shoulders of giants like Ronny and Craig.

Despite how long the Tuesday night festivities lasted, quite a few people managed to make the first presentation on Wednesday morning. I’m old so I had gone to bed fairly early and was able to see “Make IT Monitoring Ready for Cloud-native Systems” bright and early.

This presentation focused on a project called RealOpInsight. This seems to be a sort of “Manager of Managers” for multiple monitoring applications, and I didn’t really see a “cloud-native” focus in the presentation. It is open-source so if you find yourself running many instances of disparate monitoring platforms you may find RealOpInsight useful.

This was followed by a presentation from Uber.

One can imagine the number of metrics an organization like Uber collects (and I did refrain myself from making snarky comments like “what database do you use to track celebrities?” and “where do you count the number of assaults by Uber drivers?”). Rob Skillington seemed pretty cool and I didn’t want to put him on the spot.

Uber used to use Cassandra, which is a storage option for OpenNMS, but they found when they hit around 80,000 metrics per second the system couldn’t keep up (one of the largest OpenNMS deployments is 20,000 metrics/sec so 80K is a lot). Their answer was to create a new storage system called M3DB. While it seems pretty impressive, I did ask some questions about how mature it was because at OpenNMS we are always looking out for ways to make things easier for our users, and Rob admitted that while it works well for Uber it needs some work to be generally useful, which is why they open-sourced it. We’ll keep an eye on it.

The next time slot was the “German only” one I mentioned in my last post, so I engaged in the hallway track until lunch.

It was lovely to see Rihards Olups again. We met at the first OSMC I attended when he was part of the “Latvian Army” at Zabbix. He gave an entertaining talk on dealing with the alerts from your monitoring system, and he ended with the tag line “Make Alerts Meaningful Again (MAMA)”. Seems like a perfect slogan for a ball cap, preferably in red.

Another delightful human being I got to see was Dave Kempe, who came all the way from Sydney. While we had met at a prior OSMC, this conference we ended up spending a lot more time together (he was in the Prometheus training as well as the Thursday Hackathon). He gave a talk on being a monitoring consultant, and it was interesting to compare his experiences with my own (they were similar).

For most people the conference ended on Wednesday. I said goodbye to people like Peter Eckel and looked forward to the next OSMC so I could see them again.

Speaking of the next OSMC, we are going to be doing OpenNMS training on that first day, November 4th, so save the date. It is the least we could do since they went to the trouble to advertise OpenNMS Horizon® on all their posters (grin).

Ronny and I were hanging around for the Hackathon on Thursday, and for those attendees there was a nice dinner at a local restaurant called Tapasitos. It was fun to spend more time with the OSMC gang and to get ready for our last day at the conference.