Using a Device Shadow to notify device(s) of new OTA update

Question

Hello,

I am looking to use device shadows for my device (ESP32) and am looking for some guidance on how I could have a creation of an AWS job update a device's desired shadow state to a newer version of firmware. I would like to have my device to then check this desired state and if the device's current firmware version is a lower version then it would start an OTA update on my device. My initial thoughts is to use the reserved MQTT topics from AWS Jobs API to notify via MQTT (/jobs/notify or /jobs/notify-next?), look to trigger a device shadow desired state change to the version number. The device would then check the desired section of its shadow and if the version is lower it would then proceed with an OTA update. For more context, I will have multiple devices that will require the same firmware.

Philipp S · Answer

Hi kevinah,

to create OTA update you can use [AWS IoT jobs](https://docs.aws.amazon.com/iot/latest/developerguide/jobs-devices.html). There is no need to use the shadow device. You can place for example the desired firmware version in the [job template](https://docs.aws.amazon.com/iot/latest/developerguide/job-templates.html) for your OTA job.

You can find examples for (OTA) jobs for [FreeRTOS](https://docs.aws.amazon.com/freertos/latest/userguide/dev-guide-ota-workflow.html) or the [AWS IoT Device Client](https://github.com/awslabs/aws-iot-device-client/blob/main/source/jobs/README.md#sample-jobs).

Cheers,  
Philipp

Using a Device Shadow to notify device(s) of new OTA update

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