Explanation
The module twin for the IoT Edge agent is called $edgeAgent and coordinates the communications between the IoT Edge agent running on a device and IoT Hub. The desired properties are set when applying a deployment manifest on a specific device as part of a single-device or at-scale deployment.
These properties include: runtime.settings.registryCredentials.{registryId}.username runtime.settings.registryCredentials.registryId}.password Reference:
https://docs.microsoft.com/en-us/azure/iot-edge/module-edgeagent-edgehub