Google Cloud - Detecting Offline Devices

Question

I am rather new to Google Cloud IoT Core and the associated services, and have come across a problem for which I can find no "best practice" solution.

Using Google Cloud IoT Core to receive telemetry data from IoT Devices, what is the best way to detect when an IoT Sensor Device goes offline or becomes silent? Other Cloud based IoT Service implementations have built-in notification timeouts for generating alerts, but I can find no similar for Google IoT

Example: A number of IoT Edge devices monitors the temperature of cold storage rooms, and pushes a measurement every minute to a Google Cloud IoT Core, via MQTT or HTTP through WiFi or mobile data connections. If the measured temperature exceeds acceptable limits, an alert message is triggered, and routed to operational service personnel.

However, if one of the IoT Edge sensors suddenly stops operating, for whatever reason, how can this be detected by Google Cloud IoT services? Obviously, the only sign of something being wrong, is that no messages have been received from a certain DeviceID for a period substantially longer than the configured messaging-interval, e.g. 2 x interval + grace_period, so that an alert can be generated to warn of a lack of telemetry data, possibly caused by a power failure, which needs to be addressed?

Is there any standard-means by which an "IoT Device Presence" status can be automatically maintained for each device, based on the (lack of) received telemetry data from the device, in such a way, that the state change (online/offline transitions) can cause alert messages to be generated?

Or will it require a separate scheduled service to iterate all (supposedly active) devices, measuring the duration since the last received telemetry (temperature) update, and updating the device presence status directly?

One thing to clarify here is what the true problem is. If the issue you describe is that the device simply stopped sending sensor readings due to an internal error, but it is still connected to the MQTT broker, that is not something IoT Core can track directly as it is a part of your application. However, if the issue is because the device lost connectivity, that is something you can track using Alex's answer. — devunwired

Alex Hong Alex Hong · Accepted Answer · 2019-02-25T18:14:23

Assuming you just want disconnect events, there was a solution posted earlier that involves setting up StackDriver logs that exports messages to Pub/Sub. From there, you can handle the event in a Cloud Function to send an email in a similar way to what is available in your listed implementation. It takes more time to set up, but is more flexible in terms of what you can do with connect/disconnect events.

Google Core IoT Device Offline Event or Connection Status

Google Cloud - Detecting Offline Devices

1 Answers