Skip to main content

Azure Function with IoT Hub Trigger

Summary​

Configure Javascript Function Apps​

Azure IoT Hub trigger for Azure Functions

Create a Function App with VS Code​

Develop Azure Functions by using Visual Studio Code

Connection Strings​

There are two critical strings available from the Azure Portal that are required to connect your Function App to an IoT Hub:

  1. Event Hub-compatible name
  2. Event Hub compatible endpoint

Both of these strings can be found under the IoT Hub > Hub settings > Built-in endpoints.

To configure your Function App with these strings you must:

  1. Edit function.json and specify the binding "eventHubName" with string (1) from above.
  2. Edit function.json and specify the binding "connection" with a variable name that you will define in the next step (for example, eventHubConnectionAppSetting)
  3. Define the connection variable:
    • If debugging locally, add a value to your local.settings.json with the key defined previously and the endpoint string (2) from above.
    • If hosted in Azure, add an AppSetting to the Function App matching the key defined previously and the endpoint string (2) from above.

Sample functions.json​

{
  "bindings": [
    {
      "type": "eventHubTrigger",
      "name": "IoTHubMessages",
      "direction": "in",
      "eventHubName": "iothub-ehub-gqciothub-24046002-aaec6b17f1",
      "connection": "eventHubConnectionAppSetting",
      "cardinality": "many",
      "consumerGroup": "$Default",
      "dataType": "string"
    }
  ]
}

Sample local.settings.json​

{
  "IsEncrypted": false,
  "Values": {
    "FUNCTIONS_WORKER_RUNTIME": "node",
    "APPINSIGHTS_INSTRUMENTATIONKEY": "xx",
    "APPLICATIONINSIGHTS_CONNECTION_STRING": "xx",
    "FUNCTIONS_EXTENSION_VERSION": "~4",
    "__WEBSITE_CONTENTAZUREFILECONNECTIONSTRING": "xx",
    "WEBSITE_CONTENTSHARE": "xx",
    "eventHubConnectionAppSetting": "Endpoint=sb://xx.servicebus.windows.net/;SharedAccessKeyName=xx;SharedAccessKey=xxxx"
  }
}