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Emulating multiple IoT devices

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Updated at August 29, 2024

In this scenario, you will learn to emulate multiple devices that send messages to MQTT topics. The example shows the emulation of air sensors that measure the following parameters:

  • Temperature
  • Humidity
  • Pressure
  • CO2 level

Each sensor sends its readings in JSON format. Here is an example:

{
  "DeviceId":"0e3ce1d0-1504-4325-972f-55c961319814",
  "TimeStamp":"2020-05-21T22:53:16Z",
  "Values":[{
    "Type":"Float",
    "Name":"Humidity",
    "Value":"25.281837"
  },
  {
    "Type":"Float",
    "Name":"CarbonDioxide",
    "Value":"67.96608"
  },
  {
    "Type":"Float",
    "Name":"Pressure",
    "Value":"110.7021"
  },
  {
    "Type":"Float",
    "Name":"Temperature",
    "Value":"127.708824"
  }]
}

To emulate the operation of multiple devices:

  1. Prepare your cloud.
  2. Install Terraform.
  3. Describe the infrastructure.
  4. Deploy cloud resources.

If you no longer need the resources you created, delete them.

Prepare your cloud

Sign up for Yandex Cloud and create a billing account:

  1. Go to the management console and log in to Yandex Cloud or create an account if you do not have one yet.
  2. On the Yandex Cloud Billing page, make sure you have a billing account linked and it has the ACTIVE or TRIAL_ACTIVE status. If you do not have a billing account, create one.

If you have an active billing account, you can go to the cloud page to create or select a folder for your infrastructure to operate in.

Learn more about clouds and folders.

Install Terraform

Using Terraform in Yandex Cloud, you can create cloud resources of any type, such as VMs, disks, or images. For more information about the resources you can create with Terraform, see the provider documentation.

From a mirror

Alert

The mirror may be unavailable.

You can download a Terraform distribution for your platform from a mirror. When the download is complete, add the path to the folder with the executable to the PATH variable:

export PATH=$PATH:/path/to/terraform

From the HashiCorp website

Use one of the following methods:

Use one of the following methods:

Describe the infrastructure

  1. Create the iot-terraform directory. It will store the Terraform configuration files.

  2. Download the archive with the files required to run the script and unpack it to iot-terraform.

    The archive contains:

    • common.tf: Terraform provider settings.
    • files.tf: Code file parameters to publish from the local folder.
    • function.tf: Parameters of a function to write emulated messages to devices.
    • iot_core.tf: Parameters of the registry where the devices are located.
    • output.tf.tf: Output variables.
    • publish: Files required to create a function.
    • service_account.tf: Parameters of the service accountcreated by the script.
    • trigger.tf: Parameters of the trigger to invoke a function with a specified timeout.
    • variables.tf: Variables used and their values.

  3. Edit the variables.tf file, specifying the following emulation parameters:

    • token: OAuth token for Yandex Cloud access.

    • cloud_id: Cloud ID.

    • folder_id: Folder ID.

    • zone: Availability zone.

    • device_count: Number of emulated devices.

      Note

      To emulate the operation of over 1000 devices, you need to increase quotas by making a request to technical support.

    • subtopic_for_publish: Subtopic in the following format: $devices/<device_ID>/events/<subtopic>.

    • publish_execution_timeout: Message send timeout in seconds.

    • publish_cron_expression: Schedule for sending messages to an MQTT topic as a cron expression. By default, messages send every minute.

    You can leave the remaining files unchanged.

Deploy cloud resources

  1. Go to the iot-terraform folder and check the configuration using the following command:

    terraform validate

    Result:

    Success! The configuration is valid.

  2. Format the configuration files in the current folder and subfolders:

    terraform fmt

    Result:

    main.tf
variables.tf

  3. After checking the configuration, run the command:

    terraform plan

    The terminal will display a list of resources with parameters. This is a test step; no resources will be created. If the configuration contains any errors, Terraform will point them out.

    Alert

    You will be charged for all the resources created with Terraform. Check the pricing plan carefully.

  4. To create resources, run the command:

    terraform apply

  5. Confirm creating the resources: type yes in the terminal and press Enter.

    Result:

    Outputs:

function = "d4erep.......aq085f0"
iot_core = "are.......ht10enkb3u"
service_account = "ajestqfepa.......0l6"
trigger = "a1sva8sse.......7kf6"

    Terraform will create all the required resources, and the terminal will display the IDs of the resources created. You can check the new resources and their configuration using the management console.

Delete the resources you created

  1. Delete the registry:
    1. Go to your working folder.
    2. In the list of services, select IoT Core.
    3. To the right of the registry you created, click and select Delete.
    4. Click Delete.
  2. Delete the devices:
    1. Go to your working folder.
    2. In the list of services, select IoT Core.
    3. Select the registry.
    4. Go to the Devices tab.
    5. To the right of the device you created, click and select Delete.
    6. Click Delete.
  3. Delete the function:
    1. Go to your working folder.
    2. In the list of services, select Cloud Functions.
    3. To the right of the function you created, click and select Delete.
    4. Click Delete.
  4. Delete the trigger:
    1. Go to your working folder.
    2. In the list of services, select Cloud Functions.
    3. Go to the Triggers tab.
    4. To the right of the trigger you created, click and select Delete.
    5. Click Delete.
  5. Delete the service account:
    1. Go to your working folder.
    2. At the top of the screen, go to the Service accounts tab.
    3. To the right of the service account you created, click and select Delete.
    4. Click Delete.
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