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Connecting to Azure IoT

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The very first step to enable thin-edge.io is to connect your device to the cloud.

  • This is a 10 minutes operation to be done only once.
  • It establishes a permanent connection from your device to the cloud end-point.
  • This connection is secure (encrypted over TLS), and the two peers are identified by x509 certificates.
  • Sending data to the cloud will then be as simple as sending data locally.

The focus is here on connecting the device to Azure IoT. See this tutorial, if you want to connect Cumulocity IoT instead. See this tutorial, if you want to connect AWS IoT instead.

Before you try to connect your device to Azure IoT, you need:

You can now use tedge command to:

Create the certificate​

The tedge cert create command creates a self-signed certificate which can be used for testing purpose.

A single argument is required: an identifier for the device. This identifier will be used to uniquely identify your devices among others in your cloud tenant. This identifier will be also used as the Common Name (CN) of the certificate. Indeed, this certificate aims to authenticate that this device is the device with that identity.

sudo tedge cert create --device-id "undefined"
Output
Certificate was successfully created

Show certificate details​

You can then check the content of that certificate.

sudo tedge cert show
Device certificate: /etc/tedge/device-certs/tedge-certificate.pem
Subject: CN=undefined, O=Thin Edge, OU=Test Device
Issuer: CN=undefined, O=Thin Edge, OU=Test Device
Valid from: Tue, 09 Mar 2021 14:10:30 +0000
Valid up to: Thu, 10 Mar 2022 14:10:30 +0000
Thumbprint: 860218AD0A996004449521E2713C28F67B5EA580

You may notice that the issuer of this certificate is the device itself. This is a self-signed certificate. The Thumbprint is the Sha1sum of the certificate. This is required for registering the device using the self-signed certificate on Azure IoT Hub. To use a certificate signed by your Certificate Authority, see the reference guide of tedge cert.

Register the device on Azure IoT Hub​

For a device to be trusted by Azure, one needs to add the self-signed certificate thumbprint to the Azure IoT Hub Portal. In the Azure IoT Hub Portal, navigate to Explores → IoT Devices click on "+ New", this will open a new blade "Create a device".

Here provide the configuration parameters that are required to create the device as described below.

  • Device ID: Should be the same as the Subject of the certificate.
  • Authentication type: Select X.509 Self-Signed option.
    • Provide the Primary Thumbprint that was displayed in tedge cert show.
    • Use the same for the Secondary Thumbprint as well (Since we are using a single certificate).
  • Set "Connect this device to an IoT Hub" to Enable.
  • Then save the configuration. Upon successfully saved the configuration a new device has been created on the IoT Hub. The new device can be seen on the IoT Hub portal by navigating to Explores → IoT Devices.

More info about registering a device can be found here

Configure the device​

To connect the device to the Azure IoT Hub, one needs to set the URL/Hostname of the IoT Hub and the root certificate of the IoT Hub as below.

Set the URL/Hostname of your Azure IoT Hub.

sudo tedge config set az.url undefined

The URL/Hostname can be found in the Azure web portal, clicking on the overview section of your IoT Hub.

Set the path to the root certificate if necessary. The default is /etc/ssl/certs.

sudo tedge config set az.root_cert_path /etc/ssl/certs/Baltimore_CyberTrust_Root.pem

This will set the root certificate path of the Azure IoT Hub. In most of the Linux flavors, the certificate will be present in /etc/ssl/certs. If not found download it from here.

Connect the device​

Now, you are ready to get your device connected to Azure IoT Hub with tedge connect az. This command configures the MQTT broker:

  • to establish a permanent and secure connection to the Azure cloud,
  • to forward local messages to the cloud and vice versa.

Also, if you have installed tedge-mapper, this command starts and enables the tedge-mapper-az systemd service. At last, it sends packets to Azure IoT Hub to check the connection.

sudo tedge connect az
Output
Checking if systemd is available.

Checking if configuration for requested bridge already exists.

Validating the bridge certificates.

Saving configuration for requested bridge.

Restarting mosquitto service.

Awaiting mosquitto to start. This may take up to 5 seconds.

Enabling mosquitto service on reboots.

Successfully created bridge connection!

Sending packets to check connection. This may take up to 2 seconds.

Connection check is successful.

Checking if tedge-mapper is installed.

Starting tedge-mapper-az service.

Persisting tedge-mapper-az on reboot.

tedge-mapper-az service successfully started and enabled!

If your device does not have internet access and you want to create the bridge configuration, you can run a tedge connect az with the --offline flag.

sudo tedge connect az --offline
Output
Checking if systemd is available.

Checking if configuration for requested bridge already exists.

Validating the bridge certificates.

Saving configuration for requested bridge.

Restarting mosquitto service.

Awaiting mosquitto to start. This may take up to 5 seconds.

Enabling mosquitto service on reboots.

Successfully created bridge connection!

Offline mode. Skipping connection check.

Checking if tedge-mapper is installed.

Starting tedge-mapper-az service.

Persisting tedge-mapper-az on reboot.

tedge-mapper-az service successfully started and enabled!

Sending your first telemetry data​

Sending data to Azure is done using MQTT over topics prefixed with az. Any messages sent on the topic will be forwarded to Azure. Here, we publish a json message to Azure via the tedge mqtt topic.

tedge mqtt pub 'te/device/main///m/environment' '{
  "temperature": 21.3
}'

Alternatively, post your own custom messages on az/messages/events/# topic:

tedge mqtt pub 'az/messages/events/' '{
  "text": "My message"
}'

To view the messages that were sent from the device to the cloud, follow this document.

More info about sending telemetry to Azure can be found here

Next Steps​

You can now: