Emulating multiple IoT devices

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 levels.

Each sensor sends its result in JSON format. For 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 these resources, delete them.

Prepare your cloudPrepare 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 TerraformInstall Terraform

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

From a mirrorFrom a mirror

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 websiteFrom the HashiCorp website

Describe the infrastructureDescribe 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 account created 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: ID of the folder.

   • 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 resourcesDeploy 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 are 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 plan carefully.

4. To create resources, run the command:

   terraform apply
   

5. Confirm the resource creation: 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 whether the resources are there, as well as verify their settings, using the management console.

Delete the resources you createdDelete the resources you created