The systree functionality is enabled by default and reports the broker metrics at a fixed interval defined in the vernemq.conf. The metrics defined here are transformed to MQTT topics e.g. mqtt_publish_received is transformed to $SYS/<nodename>/mqtt/publish/received. <nodename> is your node's name, as configured in the vernemq.conf. To find it, you can grep the file for it: grep nodename vernemq.conf

The complete list of metrics can be found here.

systree_interval = 20000

This option defaults to 20000 milliseconds.

If the systree feature is not required it can be disabled in vernemq.conf

systree_enabled = off


mosquitto_sub -t \$SYS/<node-name>/\# -u <username> -P <password> -d