collectd "Exec" plugin for MQTT
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Latest commit 24bc4bf Jun 13, 2016 @jpmens fix rename of simple values


mqttcollect - MQTT-based Exec-plugin for collectd


mqttcollect [-v ] [-f file]


mqttcollect is an executable program which is used with collectd(1). It subscribes to any number of MQTT topics you specify, and prints values to stdout for collectd to process in an exec plugin block.

PUTVAL tiggr/mqtt‐sys/gauge‐clients.inactive 1430914033:0.00

collectd launches mqttcollect which connects to the configured MQTT broker, subscribes and waits for publishes to subscribed topics in an endless loop. If an error occurs or the program exits for whichever reason, collectd will restart and log the reason in its log file.

mqttcollect supports TLS connections to the MQTT broker, username/password authentication, and TLS-PSK, all configured via its configuration file.


mqttcollect understands the following options.

-f file : Specify an ini-type configuration file (see below), which defaults to /usr/local/etc/mqttcollect.ini.

-v : Verbose.


mqttcollect requires a configuration file to operate. This ini-type file must have a [defaults] section in which general program parameters are configured, and it will have any number of additional sections specifying the MQTT topics it is to subscribe to. For the defaults section, please consult the example file provided with the source code for a list of allowed settings.

Within a topic section, metrics collected by collectd are specified.

host = localhost
port = 1883

; (1) subscribe to a wildcard and produce three metrics per subscription.
; the metric names are interpolated with `tid' from the JSON message
; payload, and the values of each metric are obtained from the
; JSON element behind the `<'

gauge = vehicle/{tid}/speed<vel
gauge = vehicle/{tid}/altitude<alt
counter = vehicle/{tid}/odometer<trip

; (2) subscribe to one topic and rename the metric

gauge = clients.inactive

; (3) subscribe to one topic and KEEP its name
; use the "*"-form for wildcarded topics

gauge = *

Example 1 is complex. mqttcollect will subscribe to the wildcarded owntracks/+/+ topic, and for each message received on that topic, will produce three metrics. The special character < in the line indicates the MQTT message payload is expected to be JSON. Each of the metric names will have the JSON element tid from the payload interpolated into their names, and the actual value of the metric will be obtained (<) from the specified JSON element (vel, alt, and trip respectively). Using this configuration, and assuming a payload with this JSON

{"tid": "BB", "vel": 62, "trip": 8246531, "alt": 48}

mqttcollect could produce the following three metrics for collectd:

PUTVAL tiggr/mqttcollect/gauge-vehicle/BB/speed 1431535440:62.00
PUTVAL tiggr/mqttcollect/gauge-vehicle/BB/altitude 1431535440:48.00
PUTVAL tiggr/mqttcollect/counter-vehicle/BB/odometer 1431535440:8246531.00

In example 2, the program will subscribe to a single topic, and will produce a metric renamed to clients.inactive.

PUTVAL tiggr/mqttcollect/gauge-clients.inactive 1431535434:1.00

Example 3 subscribes to the single topic and does not rename the metric (note the *); this is what you'll typically use for wildcarded topic subscribes.

PUTVAL tiggr/mqttcollect/gauge-$SYS/broker/load/messages/received/1min 1431535557:61.47


As an example, we show how to configure InfluxDB to accept values from collectd via the latter’s network plugin. Configure InfluxDB to launch the native collectd input:


  enabled = true
  # address = "" # defaults to bind‐address.
  port = 25826
  database = "collectd"
  typesdb = "/usr/share/collectd/types.db"


Configure collectd to send its metrics to InfluxDB via the network plugin which talks to InfluxDB. (Compare the port numbers here and above in InfluxDB.)

LoadPlugin network

<Plugin "network">
   # influxdb
   Server "" "25826"

Configure collectd to load our executable mqttcollect via its exec mechanism. Specify mqttcollect's options as individual strings in the Exec invocation.

LoadPlugin exec

<Plugin exec>
   Exec "mosquitto:mosquitto" "/usr/bin/mqttcollect" "‐f" "/etc/my.ini"






  • Obtain the source code for mqttcollect, adjust the Makefile and run make.



Jan-Piet Mens