Create and provision IoT Edge devices at scale on Linux using symmetric key

Applies to: IoT Edge 1.1

Important

IoT Edge 1.1 end of support date was December 13, 2022. Check the Microsoft Product Lifecycle for information about how this product, service, technology, or API is supported. For more information about updating to the latest version of IoT Edge, see Update IoT Edge.

This article provides end-to-end instructions for autoprovisioning one or more Linux IoT Edge devices using symmetric keys. You can automatically provision Azure IoT Edge devices with the Azure IoT Hub device provisioning service (DPS). If you're unfamiliar with the process of autoprovisioning, review the provisioning overview before continuing.

The tasks are as follows:

1. Create either an individual enrollment for a single device or a group enrollment for a set of devices.
2. Install the IoT Edge runtime and connect to the IoT Hub.

Symmetric key attestation is a simple approach to authenticating a device with a device provisioning service instance. This attestation method represents a "Hello world" experience for developers who are new to device provisioning, or do not have strict security requirements. Device attestation using a TPM or X.509 certificates is more secure, and should be used for more stringent security requirements.

Prerequisites

Cloud resources

• An active IoT hub
• An instance of the IoT Hub device provisioning service in Azure, linked to your IoT hub
  • If you don't have a device provisioning service instance, you can follow the instructions in the Create a new IoT Hub device provisioning service and Link the IoT hub and your device provisioning service sections of the IoT Hub device provisioning service quickstart.
  • After you have the device provisioning service running, copy the value of ID Scope from the overview page. You use this value when you configure the IoT Edge runtime.

Device requirements

A physical or virtual Linux device to be the IoT Edge device.

You will need to define a unique registration ID to identify each device. You can use the MAC address, serial number, or any unique information from the device. For example, you could use a combination of a MAC address and serial number forming the following string for a registration ID: sn-007-888-abc-mac-a1-b2-c3-d4-e5-f6. Valid characters are lowercase alphanumeric and dash (-).

Create a DPS enrollment

Create an enrollment to provision one or more devices through DPS.

If you are looking to provision a single IoT Edge device, create an individual enrollment. If you need multiple devices provisioned, follow the steps for creating a DPS group enrollment.

When you create an enrollment in DPS, you have the opportunity to declare an initial device twin state. In the device twin, you can set tags to group devices by any metric you need in your solution, like region, environment, location, or device type. These tags are used to create automatic deployments.

For more information about enrollments in the device provisioning service, see How to manage device enrollments.

Individual enrollment

Create a DPS individual enrollment

Tip

The steps in this article are for the Azure portal, but you can also create individual enrollments using the Azure CLI. For more information, see az iot dps enrollment. As part of the CLI command, use the edge-enabled flag to specify that the enrollment is for an IoT Edge device.

1. In the Azure portal, navigate to your instance of IoT Hub device provisioning service.

2. Under Settings, select Manage enrollments.

3. Select Add individual enrollment then complete the following steps to configure the enrollment:

   1. For Mechanism, select Symmetric Key.

   2. Provide a unique Registration ID for your device.

   3. Optionally, provide an IoT Hub Device ID for your device. You can use device IDs to target an individual device for module deployment. If you don't provide a device ID, the registration ID is used.

   4. Select True to declare that the enrollment is for an IoT Edge device.

   5. Optionally, add a tag value to the Initial Device Twin State. You can use tags to target groups of devices for module deployment. For example:

      {
         "tags": {
            "environment": "test"
         },
         "properties": {
            "desired": {}
         }
      }
      

   6. Select Save.

4. Copy the individual enrollment's Primary Key value to use when installing the IoT Edge runtime.

Now that an enrollment exists for this device, the IoT Edge runtime can automatically provision the device during installation.

Group enrollment

Create a DPS group enrollment

Tip

The steps in this article are for the Azure portal, but you can also create group enrollments using the Azure CLI. For more information, see az iot dps enrollment-group. As part of the CLI command, use the edge-enabled flag to specify that the enrollment is for IoT Edge devices. For a group enrollment, all devices must be IoT Edge devices or none of them can be.

1. In the Azure portal, navigate to your instance of IoT Hub device provisioning service.

2. Under Settings, select Manage enrollments.

3. Select Add individual enrollment then complete the following steps to configure the enrollment:

   1. Provide a Group name.

   2. Select Symmetric Key as the attestation type.

   3. Select True to declare that the enrollment is for an IoT Edge device. For a group enrollment, all devices must be IoT Edge devices or none of them can be.

   4. Optionally, add a tag value to the Initial Device Twin State. You can use tags to target groups of devices for module deployment. For example:

      {
         "tags": {
            "environment": "test"
         },
         "properties": {
            "desired": {}
         }
      }
      

   5. Select Save.

4. Copy your enrollment group's Primary Key value to use when creating device keys for use with a group enrollment.

Now that an enrollment group exists, the IoT Edge runtime can automatically provision devices during installation.

Derive a device key

Each device that is provisioned as part of a group enrollment needs a derived device key to perform symmetric key attestation with the enrollment during provisioning.

To generate a device key, use the key that you copied from your DPS enrollment group to compute an HMAC-SHA256 of the unique registration ID for the device and convert the result into Base64 format.

Important

Do not include your enrollment's primary or secondary key in your device code.

On Windows, you can use PowerShell to generate your derived device key as shown in the following example.

Replace the value of KEY with the Primary Key you noted earlier.

Replace the value of REG_ID with your device's registration ID.

$KEY='PASTE_YOUR_ENROLLMENT_KEY_HERE'
$REG_ID='PASTE_YOUR_REGISTRATION_ID_HERE'

$hmacsha256 = New-Object System.Security.Cryptography.HMACSHA256
$hmacsha256.key = [Convert]::FromBase64String($KEY)
$sig = $hmacsha256.ComputeHash([Text.Encoding]::ASCII.GetBytes($REG_ID))
$derivedkey = [Convert]::ToBase64String($sig)
echo "`n$derivedkey`n"

Below is a sample output of a derived device key:

Jsm0lyGpjaVYVP2g3FnmnmG9dI/9qU24wNoykUmermc=

Install IoT Edge

In this section, you prepare your Linux VM or physical device for IoT Edge. Then, you install IoT Edge.

Run the following commands to add the package repository and then add the Microsoft package signing key to your list of trusted keys.

Important

On June 30, 2022 Raspberry Pi OS Stretch was retired from the Tier 1 OS support list. To avoid potential security vulnerabilities update your host OS to Bullseye.

Ubuntu

Installing can be done with a few commands. Open a terminal and run the following commands:

• 20.04:

  wget https://packages.microsoft.com/config/ubuntu/20.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
  sudo dpkg -i packages-microsoft-prod.deb
  rm packages-microsoft-prod.deb
  

• 18.04:

  wget https://packages.microsoft.com/config/ubuntu/18.04/multiarch/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
  sudo dpkg -i packages-microsoft-prod.deb
  rm packages-microsoft-prod.deb
  

Debian

Installing with APT can be done with a few commands. Open a terminal and run the following commands:

• 11 - Bullseye (arm32v7):

  curl https://packages.microsoft.com/config/debian/11/packages-microsoft-prod.deb > ./packages-microsoft-prod.deb
  sudo apt install ./packages-microsoft-prod.deb
  

Tip

If you gave the "root" account a password during the OS install, you will not need 'sudo' and can run the above command by starting with 'apt'.

Red Hat Enterprise Linux

Installing can be done with a few commands. Open a terminal and run the following commands:

• 8.x (amd64):

    wget https://packages.microsoft.com/config/rhel/8/packages-microsoft-prod.rpm -O packages-microsoft-prod.rpm
    sudo yum localinstall packages-microsoft-prod.rpm
    rm packages-microsoft-prod.rpm
  

Note

Azure IoT Edge software packages are subject to the license terms located in each package (usr/share/doc/{package-name} or the LICENSE directory). Read the license terms prior to using a package. Your installation and use of a package constitutes your acceptance of these terms. If you don't agree with the license terms, don't use that package.

Install a container engine

Azure IoT Edge relies on an OCI-compatible container runtime. For production scenarios, we recommend that you use the Moby engine. The Moby engine is the only container engine officially supported with IoT Edge. Docker CE/EE container images are compatible with the Moby runtime.

Ubuntu

Install the Moby engine.

sudo apt-get update; \
  sudo apt-get install moby-engine

Debian

Install the Moby engine.

sudo apt-get update; \
  sudo apt-get install moby-engine

Red Hat Enterprise Linux

Install the Moby engine and CLI.

sudo yum install moby-engine moby-cli

Once the Moby engine is successfully installed, configure it to use local logging driver as the logging mechanism. To learn more about logging configuration, see Production Deployment Checklist.

• Create or open the Docker daemon's config file at /etc/docker/daemon.json.

• Set the default logging driver to the local logging driver as shown in the example below.

     {
        "log-driver": "local"
     }
  

• Restart the container engine for the changes to take effect.

  sudo systemctl restart docker
  

  Tip

  If you get errors when you install the Moby container engine, verify your Linux kernel for Moby compatibility. Some embedded device manufacturers ship device images that contain custom Linux kernels without the features required for container engine compatibility. Run the following command, which uses the check-config script provided by Moby, to check your kernel configuration:

  curl -ssl https://raw.githubusercontent.com/moby/moby/master/contrib/check-config.sh -o check-config.sh
  chmod +x check-config.sh
  ./check-config.sh
  

  In the output of the script, check that all items under Generally Necessary and Network Drivers are enabled. If you're missing features, enable them by rebuilding your kernel from source and selecting the associated modules for inclusion in the appropriate kernel .config. Similarly, if you're using a kernel configuration generator like defconfig or menuconfig, find and enable the respective features and rebuild your kernel accordingly. After you've deployed your newly modified kernel, run the check-config script again to verify that all the required features were successfully enabled.

Install the IoT Edge runtime

The IoT Edge security daemon provides and maintains security standards on the IoT Edge device. The daemon starts on every boot and bootstraps the device by starting the rest of the IoT Edge runtime.

The steps in this section represent the typical process to install the latest version on a device that has internet connection. If you need to install a specific version, like a pre-release version, or need to install while offline, follow the Offline or specific version installation steps later in this article.

Install IoT Edge version 1.1.* along with the libiothsm-std package:

Ubuntu

sudo apt-get update; \
  sudo apt-get install iotedge

Debian

sudo apt-get update; \
  sudo apt-get install iotedge

Red Hat Enterprise Linux

IoT Edge version 1.1 isn't supported on Red Hat Enterprise Linux 8.

Note

IoT Edge version 1.1 is the long-term support branch of IoT Edge. If you are running an older version, we recommend installing or updating to the latest patch as older versions are no longer supported.

Provision the device with its cloud identity

Once the runtime is installed on your device, configure the device with the information it uses to connect to the device provisioning service and IoT Hub.

Have the following information ready:

• The DPS ID Scope value
• The device Registration ID you created
• Either the Primary Key from an individual enrollment, or a derived key for devices using a group enrollment.

1. Open the configuration file on the IoT Edge device.

   sudo nano /etc/iotedge/config.yaml
   

2. Find the provisioning configurations section of the file. Uncomment the lines for DPS symmetric key provisioning, and make sure any other provisioning lines are commented out.

   The provisioning: line should have no preceding whitespace, and nested items should be indented by two spaces.

   # DPS TPM provisioning configuration
   provisioning:
     source: "dps"
     global_endpoint: "https://global.azure-devices-provisioning.net"
     scope_id: "PASTE_YOUR_SCOPE_ID_HERE"
     attestation:
       method: "symmetric_key"
       registration_id: "PASTE_YOUR_REGISTRATION_ID_HERE"
       symmetric_key: "PASTE_YOUR_PRIMARY_KEY_OR_DERIVED_KEY_HERE"
   
   # always_reprovision_on_startup: true
   # dynamic_reprovisioning: true
   

3. Update the values of scope_id, registration_id, and symmetric_key with your DPS and device information.

4. Optionally, use the always_reprovision_on_startup or dynamic_reprovisioning lines to configure your device's reprovisioning behavior. If a device is set to reprovision on startup, it will always attempt to provision with DPS first and then fall back to the provisioning backup if that fails. If a device is set to dynamically reprovision itself, IoT Edge (and all modules) will restart and reprovision if a reprovisioning event is detected, like if the device is moved from one IoT Hub to another. Specifically, IoT Edge checks for bad_credential or device_disabled errors from the SDK to detect the reprovision event. To trigger this event manually, disable the device in IoT Hub. For more information, see IoT Hub device reprovisioning concepts.

5. Restart the IoT Edge runtime so that it picks up all the configuration changes that you made on the device.

   sudo systemctl restart iotedge
   

Verify successful installation

If the runtime started successfully, you can go into your IoT Hub and start deploying IoT Edge modules to your device.

Individual enrollment

You can verify that the individual enrollment that you created in device provisioning service was used. Navigate to your device provisioning service instance in the Azure portal. Open the enrollment details for the individual enrollment that you created. Notice that the status of the enrollment is assigned and the device ID is listed.

Group enrollment

You can verify that the group enrollment that you created in device provisioning service was used. Navigate to your device provisioning service instance in the Azure portal. Open the enrollment details for the group enrollment that you created. Go to the Registration Records tab to view all devices registered in that group.

Use the following commands on your device to verify that the IoT Edge installed and started successfully.

Check the status of the IoT Edge service.

systemctl status iotedge

Examine service logs.

journalctl -u iotedge --no-pager --no-full

List running modules.

iotedge list

Next steps

The device provisioning service enrollment process lets you set the device ID and device twin tags at the same time as you provision the new device. You can use those values to target individual devices or groups of devices using automatic device management. Learn how to Deploy and monitor IoT Edge modules at scale using the Azure portal or using Azure CLI.