Remotely collect diagnostic logs from devices using Device Update for IoT Hub

Learn how to initiate a Device Update for IoT Hub log operation and view collected logs within Azure blob storage.

Prerequisites

• Access to an IoT Hub with Device Update for IoT Hub enabled.
• An IoT device (or simulator) provisioned for Device Update within IoT Hub and implementing the Diagnostic Interface.
• An Azure Blob storage account under the same subscription as your Device Update for IoT Hub account.

Note

The remote log collection feature is currently compatible only with devices that implement the Diagnostic Interface and are able to upload files to Azure Blob storage. The reference agent implementation also expects the device to write log files to a user-specified file path on the device.

Azure portal

Supported browsers:

• Microsoft Edge
• Google Chrome

Azure CLI

An Azure CLI environment:

• Use the Bash environment in Azure Cloud Shell.

  

• Or, if you prefer to run CLI reference commands locally, install the Azure CLI

  • Sign in to the Azure CLI by using the az login command.
  • Run az version to find the version and dependent libraries that are installed. To upgrade to the latest version, run az upgrade.
  • When prompted, install Azure CLI extensions on first use. The commands in this article use the azure-iot extension. Run az extension update --name azure-iot to make sure you're using the latest version of the extension.

Tip

The Azure CLI commands in this article use the backslash \ character for line continuation so that the command arguments are easier to read. This syntax works in Bash environments. If you're running these commands in PowerShell, replace each backslash with a backtick ```, or remove them entirely.

Link your Azure Blob storage account to your Device Update instance

In order to use the remote log collection feature, you must first link an Azure Blob storage account with your Device Update instance. This Azure Blob storage account is where your devices will upload diagnostic logs to.

Azure portal

1. In the Azure portal, navigate to your Device Update for IoT Hub account.

2. Select Instances under the Instance Management section of the navigation pane.

3. Select your Device Update instance from the list, then Configure Diagnostics.

4. Select the Customer Diagnostics tab, then Select Azure Storage Account.

5. Choose your desired storage account from the list and select Save.

6. Once back on the instance list, select Refresh periodically until the instance's provisioning state shows "Succeeded." This process usually takes 2-3 minutes.

Azure CLI

Use the az iot du instance create command to configure diagnostics for your Device Update instance.

Tip

You can use the az iot du instance create command on an existing Device Update instances and it will configure the instance with the updated parameters.

Replace the following placeholders with your own information:

• <account_name>: The name of your Device Update account.
• <instance_name>: The name of your Device Update instance.
• <storage_id>: The resource ID of the storage account where the diagnostics logs will be stored. You can retrieve the resource ID by using the az storage show command and querying for the ID value: az storage account show -n <storage_name> --query id.

az iot du instance update --account <account_name> --instance <instance_name> --set enableDiagnostics=true diagnosticStorageProperties.resourceId=<storage_id>

Configure log collection

The device update agent refers to a configuration file on the device, located at /etc/adu/du-diagnostics-config.json in the reference agent.

Log collection file paths

The Device Update agent on a device will collect files from specific file paths on the device when it receives a log upload start signal from the Device Update service. These file paths are defined in the diagnostics config file.

Within the configuration file, each log file to be collected and uploaded is represented as a logComponent object with componentName and logPath properties. This configuration can be modified as desired.

Max log file size

The Device Update agent will only collect log files under a certain file size. This max file size is defined in the diagnostics config file.

The relevant parameter "maxKilobytesToUploadPerLogPath" will apply to each logComponent object, and can be modified as desired.

Create a log operation

Log operations are a service-driven action that you can instruct your IoT devices to perform through the Device Update service. For a more detailed explanation of how log operations function, see Device update diagnostics.

Azure portal

1. Navigate to your IoT Hub and select the Updates tab under the Device Management section of the navigation pane.

2. Select the Diagnostics tab in the UI. If you don't see a Diagnostics tab, make sure you're using the newest version of the Device Update for IoT Hub user interface. If you see "Diagnostics must be enabled for this Device Update instance," make sure you've linked an Azure Blob storage account with your Device Update instance.

3. Select Add log upload operation to navigate to the log operation creation page.

4. Enter a name (ID) and description for your new log operation, then select Add devices to select which IoT devices you want to collect diagnostic logs from.

5. Select Add.

6. Once back on the Diagnostics tab, select Refresh until you see your log operation listed in the Operation Table.

7. Once the operation status is Succeeded or Failed, select the operation name to view its details. An operation will be marked "Succeeded" only if all targeted devices successfully completed the log upload. If some targeted devices succeeded and some failed, the log operation will be marked "Failed." You can use the log operation details page to see which devices succeeded and which failed.

8. In the log operation details, you can view the device-specific status and see the log location path. This path corresponds to the virtual directory path within your Azure Blob storage account where the diagnostic logs have been uploaded.

Azure CLI

Use the az iot du device log collect command to configure a diagnostics log collection operation.

The device log collect command takes the following arguments:

• --account: The Device Update account name.
• --instance: The Device Update instance name.
• --log-collection-id: A name for the log collection operation.
• --agent-id: Key=value pairs that identify a target Device Update agent for this log collection operation. Use deviceId=<device name> if the agent has a device identity. Use deviceId=<device name> moduleId=<module name> if the agent has a module identity. You can use the --agent-id parameter multiple times to target multiple devices.

For example:

az iot du device log collect \
    --account <Device Update account name> \
    --instance <Device Update instance name> \
    --log-collection-id <log collection name} \
    --agent-id deviceId=<device name> \
    --agent-id deviceId=<device name> moduleId=<module name>

Use az iot du device log show to view the details of a specific diagnostic log collection operation.

az iot du device log show \
    --account <Device Update account name> \
    --instance <Device Update instance name> \
    --log-collection-id <log collection name>

View and export collected diagnostic logs

1. Once your log operation has succeeded, navigate to your Azure Blob storage account.

2. Select Containers under the Data storage section of the navigation pane.

3. Select the container with the same name as your Device Update instance.

4. Use the log location path from the log operation details to navigate to the correct directory containing the logs. By default, the remote log collection feature instructs targeted devices to upload diagnostic logs using the following directory path model: Blob storage container/Target device ID/Log operation ID/On-device log path

5. If you haven't modified the diagnostic component of the Device Update agent, the device will respond to any log operation by attempting to upload two plaintext log files: the Device Update agent diagnostic log ("aduc.log"), and the DO agent diagnostic log ("do-agent.log"). You can learn more about which log files the Device Update reference agent collects by reading the Device Update diagnostics concept page.

6. You can view the log file's contents by selecting the file name, then selecting the menu element (ellipsis) and clicking View/edit. You can also download or delete the log file by selecting the respectively labeled options.

   

Next steps

To learn more about Device Update's diagnostic capabilities, see Device update diagnostic feature overview