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Automatic IoT device and module management using the Azure CLI

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Automatic device management in Azure IoT Hub automates many of the repetitive and complex tasks of managing large device fleets. With automatic device management, you can target a set of devices based on their properties, define a desired configuration, and then let IoT Hub update the devices when they come into scope. This update is done using an automatic device configuration or automatic module configuration, which lets you summarize completion and compliance, handle merging and conflicts, and roll out configurations in a phased approach.

Note

The features described in this article are available only in the standard tier of IoT Hub. For more information about the basic and standard/free IoT Hub tiers, see Choose the right IoT Hub tier for your solution.

Automatic device management works by updating a set of device twins or module twins with desired properties and reporting a summary that's based on twin reported properties. It introduces a new class and JSON document called a configuration that has three parts:

  • The target condition defines the scope of device twins or module twins to be updated. The target condition is specified as a query on device twin tags and/or reported properties.

  • The target content defines the desired properties to be added or updated in the targeted device twins or module twins. The content includes a path to the section of desired properties to be changed.

  • The metrics define the summary counts of various configuration states such as Success, In Progress, and Error. Custom metrics are specified as queries on twin reported properties. System metrics are the default metrics that measure twin update status, such as the number of twins that are targeted and the number of twins that have been successfully updated.

Automatic configurations run for the first time shortly after the configuration is created and then at five minute intervals. Metrics queries run each time the automatic configuration runs. A maximum of 100 automatic configurations is supported on standard tier IoT hubs; ten on free tier IoT hubs. Throttling limits also apply. To learn more, see Quotas and Throttling.

CLI prerequisites

  • An IoT hub in your Azure subscription. If you don't have a hub yet, you can follow the steps in Create an IoT hub.

  • Azure CLI in your environment. At a minimum, your Azure CLI version must be 2.0.70 or above. Use az –-version to validate. This version supports az extension commands and introduces the Knack command framework.

  • The IoT extension for Azure CLI.

Note

This article uses the newest version of the Azure IoT extension, called azure-iot. The legacy version is called azure-cli-iot-ext.You should only have one version installed at a time. You can use the command az extension list to validate the currently installed extensions.

Use az extension remove --name azure-cli-iot-ext to remove the legacy version of the extension.

Use az extension add --name azure-iot to add the new version of the extension.

To see what extensions you have installed, use az extension list.

Implement twins

Automatic device configurations require the use of device twins to synchronize state between the cloud and devices. For more information, see Understand and use device twins in IoT Hub.

Automatic module configurations require the use of module twins to synchronize state between the cloud and modules. For more information, see Understand and use module twins in IoT Hub.

Use tags to target twins

Before you create a configuration, you must specify which devices or modules you want to affect. Azure IoT Hub identifies devices and using tags in the device twin, and identifies modules using tags in the module twin. Each device or module can have multiple tags, and you can define them any way that makes sense for your solution. For example, if you manage devices in different locations, add the following tags to a device twin:

"tags": {
	"location": {
		"state": "Washington",
		"city": "Tacoma"
    }
},

Define the target content and metrics

The target content and metric queries are specified as JSON documents that describe the device twin or module twin desired properties to set and reported properties to measure. To create an automatic configuration using Azure CLI, save the target content and metrics locally as .txt files. You use the file paths in a later section when you run the command to apply the configuration to your device.

Here's a basic target content sample for an automatic device configuration:

{
  "content": {
    "deviceContent": {
      "properties.desired.chillerWaterSettings": {
        "temperature": 38,
        "pressure": 78
      }
    }
}

Automatic module configurations behave very similarly, but you target moduleContent instead of deviceContent.

{
  "content": {
    "moduleContent": {
      "properties.desired.chillerWaterSettings": {
        "temperature": 38,
        "pressure": 78
      }
    }
}

Here are examples of metric queries:

{
  "queries": {
    "Compliant": "select deviceId from devices where configurations.[[chillerdevicesettingswashington]].status = 'Applied' AND properties.reported.chillerWaterSettings.status='current'",
    "Error": "select deviceId from devices where configurations.[[chillerdevicesettingswashington]].status = 'Applied' AND properties.reported.chillerWaterSettings.status='error'",
    "Pending": "select deviceId from devices where configurations.[[chillerdevicesettingswashington]].status = 'Applied' AND properties.reported.chillerWaterSettings.status='pending'"
  }
}

Metric queries for modules are also similar to queries for devices, but you select for moduleId from devices.modules. For example:

{
  "queries": {
    "Compliant": "select deviceId, moduleId from devices.module where configurations.[[chillermodulesettingswashington]].status = 'Applied' AND properties.reported.chillerWaterSettings.status='current'"
  }
}

Create a configuration

You can create a maximum of 100 automatic configurations on standard tier IoT hubs; ten on free tier IoT hubs. To learn more, see Quotas and Throttling.

You configure target devices by creating a configuration that consists of the target content and metrics. Use the following command to create a configuration:

   az iot hub configuration create --config-id [configuration id] \
     --labels [labels] --content [file path] --hub-name [hub name] \
     --target-condition [target query] --priority [int] \
     --metrics [metric queries]

  • --config-id - The name of the configuration that will be created in the IoT hub. Give your configuration a unique name that is up to 128 characters long. Lowercase letters and the following special characters are allowed: -+%_*!'. Spaces are not allowed.

  • --labels - Add labels to help track your configuration. Labels are Name, Value pairs that describe your deployment. For example, HostPlatform, Linux or Version, 3.0.1

  • --content - Inline JSON or file path to the target content to be set as twin desired properties.

  • --hub-name - Name of the IoT hub in which the configuration will be created. The hub must be in the current subscription. Switch to the desired subscription with the command az account set -s [subscription name]

  • --target-condition - Enter a target condition to determine which devices or modules will be targeted with this configuration. For automatic device configuration, the condition is based on device twin tags or device twin desired properties and should match the expression format. For example, tags.environment='test' or properties.desired.devicemodel='4000x'. For automatic module configuration, the condition is based on module twin tags or module twin desired properties.. For example, from devices.modules where tags.environment='test' or from devices.modules where properties.reported.chillerProperties.model='4000x'.

  • --priority - A positive integer. In the event that two or more configurations are targeted at the same device or module, the configuration with the highest numerical value for Priority will apply.

  • --metrics - Filepath to the metric queries. Metrics provide summary counts of the various states that a device or module may report back after applying configuration content. For example, you may create a metric for pending settings changes, a metric for errors, and a metric for successful settings changes.

Monitor a configuration

Use the following command to display the contents of a configuration:

az iot hub configuration show --config-id [configuration id] \
  --hub-name [hub name]

  • --config-id - The name of the configuration that exists in the IoT hub.

  • --hub-name - Name of the IoT hub in which the configuration exists. The hub must be in the current subscription. Switch to the desired subscription with the command az account set -s [subscription name]

Inspect the configuration in the command window. The metrics property lists a count for each metric that is evaluated by each hub:

  • targetedCount - A system metric that specifies the number of device twins or module twins in IoT Hub that match the targeting condition.

  • appliedCount - A system metric specifies the number of devices or modules that have had the target content applied.

  • Your custom metric - Any metrics you've defined are user metrics.

You can show a list of device IDs, module IDs, or objects for each of the metrics by using the following command:

az iot hub configuration show-metric --config-id [configuration id] \
   --metric-id [metric id] --hub-name [hub name] --metric-type [type]

  • --config-id - The name of the deployment that exists in the IoT hub.

  • --metric-id - The name of the metric for which you want to see the list of device IDs or module IDs, for example appliedCount.

  • --hub-name - Name of the IoT hub in which the deployment exists. The hub must be in the current subscription. Switch to the desired subscription with the command az account set -s [subscription name].

  • --metric-type - Metric type can be system or user. System metrics are targetedCount and appliedCount. All other metrics are user metrics.

Modify a configuration

When you modify a configuration, the changes immediately replicate to all targeted devices.

If you update the target condition, the following updates occur:

  • If a twin didn't meet the old target condition, but meets the new target condition and this configuration is the highest priority for that twin, then this configuration is applied.

  • If a twin currently running this configuration no longer meets the target condition, the settings from the configuration will be removed and the twin will be modified by the next highest priority configuration.

  • If a twin currently running this configuration no longer meets the target condition and doesn't meet the target condition of any other configurations, then the settings from the configuration will be removed and no other changes will be made on the twin.

Use the following command to update a configuration:

az iot hub configuration update --config-id [configuration id] \
   --hub-name [hub name] --set [property1.property2='value']

  • --config-id - The name of the configuration that exists in the IoT hub.

  • --hub-name - Name of the IoT hub in which the configuration exists. The hub must be in the current subscription. Switch to the desired subscription with the command az account set -s [subscription name].

  • --set - Update a property in the configuration. You can update the following properties:

    • targetCondition - for example targetCondition=tags.location.state='Oregon'

    • labels

    • priority

Delete a configuration

When you delete a configuration, any device twins or module twins take on their next highest priority configuration. If twins don't meet the target condition of any other configuration, then no other settings are applied.

Use the following command to delete a configuration:

az iot hub configuration delete --config-id [configuration id] \
   --hub-name [hub name]

  • --config-id - The name of the configuration that exists in the IoT hub.

  • --hub-name - Name of the IoT hub in which the configuration exists. The hub must be in the current subscription. Switch to the desired subscription with the command az account set -s [subscription name].

Next steps

In this article, you learned how to configure and monitor IoT devices at scale.

To learn how to manage IoT Hub device identities in bulk, see Import and export IoT Hub device identities in bulk