Troubleshooting Azure IoT Edge

This section provides guidance and solutions for common issues encountered when deploying and managing Azure IoT Edge devices.

Common Issues and Solutions

1. Device Connection Failures

Symptom: IoT Edge runtime fails to connect to Azure IoT Hub.

Check network connectivity: Ensure the device has a stable internet connection and can reach IoT Hub endpoints (e.g., *.azure-devices.net).
Verify connection string: Double-check the IoT Hub device connection string configured in the config.toml file. Ensure there are no typos or missing characters.
Firewall rules: Confirm that any firewalls (local or network) are not blocking outbound connections on the required ports (typically 443, 8883, or 5671 for AMQP/MQTT over TLS).
Certificate issues: If using certificates for authentication, ensure they are valid, correctly installed, and trusted by the device.

2. Module Deployment Problems

Symptom: Custom modules fail to deploy or run as expected.

Image pull errors: Verify that the container image is correctly tagged and accessible from the specified container registry (e.g., Azure Container Registry). Check registry credentials in config.toml.
Module logs: Examine the logs of the failing module. Use the following command on the Edge device:
```
sudo iotedge logs <module-name>
```
Resource constraints: Ensure the Edge device has sufficient CPU, memory, and disk space for the deployed modules.
Dependencies: If your module relies on other modules or services, confirm they are running and configured correctly.

3. Edge Agent Not Starting

Symptom: The edgeAgent module is not running or shows errors.

Runtime installation: Reinstall the IoT Edge runtime if the installation might be corrupted. Refer to the official installation guides for your OS.
Systemd/service status: Check the status of the IoT Edge service:
```
sudo systemctl status iotedge
```
Restart the service if necessary:
```
sudo systemctl restart iotedge
```
config.toml syntax: Validate the syntax of your config.toml file. Small errors can prevent the agent from starting.

4. Communication Issues Between Modules

Symptom: Modules are unable to send or receive messages from each other.

Routing configuration: Review the routes defined in the IoT Edge deployment manifest. Ensure message sources and sinks are correctly specified.
Module identity: Verify that modules have the necessary permissions to communicate. This is typically managed by the IoT Edge security manager.
Message format: Ensure modules are producing and consuming messages in a compatible format (e.g., JSON).

5. Device Twin Synchronization Problems

Symptom: Desired properties are not reflected on the device, or reported properties are not seen in IoT Hub.

Connection status: Ensure the device is connected to IoT Hub. Device twin updates rely on an active connection.
Edge Hub logs: Check the logs for the edgeHub module for any errors related to twin synchronization.
Deployment manifest: Verify that the deployment manifest correctly defines reported properties and desired property handlers.

Tip: Regularly check the logs of the edgeAgent and edgeHub modules. They provide invaluable insights into the runtime's state and potential issues.

Diagnostic Tools

Azure IoT Edge provides several tools to help diagnose problems:

IoT Explorer: A desktop application that helps you manage and monitor IoT devices, including IoT Edge. It can be used to view twin data, invoke direct methods, and send messages.
Azure CLI: Use the Azure CLI with the IoT extension for device management, deployment, and troubleshooting.
Device Logs: As mentioned earlier, use iotedge logs on the Edge device to inspect module output.
Diagnostic Settings: Configure diagnostic settings in IoT Hub to send logs and metrics to Azure Monitor for more advanced analysis.

Warning: Always back up your config.toml file before making significant changes. Incorrect configuration can lead to runtime instability.

Troubleshooting Checklist

Verify network connectivity and firewall rules.
Confirm correct IoT Hub connection string and credentials.
Inspect module logs for specific error messages.
Check device resource utilization (CPU, memory, disk).
Review deployment manifest for correct routes and module configurations.
Validate certificates if using them for authentication.
Ensure the IoT Edge runtime service is running.
Consult Azure Monitor for detailed logs and metrics.

If you are still experiencing issues, consider consulting the official Azure IoT Edge troubleshooting documentation or the Azure support community forums.