In each probe it sends a message over MQTT broker and then wait for getting it over subscription. By measuring this time and also connection, subscription etc. durations you can check your cluster status. At Snapp! We use it to detect our EMQX clusters status from the client perspective.
m-yosefpor/mqtt-blackbox-exporter
Connect, Subscribe and Publish over MQTT broker to check its status.
GoGPL-3.0