How do I configure 'ConsumerGroup` in local.settings.json while developing Azure Function Version 2

Question

I have below code to catch all the messages arrives at IoT Hub

    [FunctionName("device-message--funcapp-v2")]
    public static void Run([IoTHubTrigger("testhub", 
                       Connection = "IoTHubEventEndPoint", 
                       ConsumerGroup = "ActualConsumerGroup")]EventData message, 
        ILogger log)
    {
        log.LogInformation($"C# IoT Hub trigger:
       {Encoding.UTF8.GetString(message.Body.Array)}");     
    }

This works fine as expected, but now I do not want to hard code the ConsumerGroup. So I added below configuraiton entry in local.settings.json

   {
     "IsEncrypted": false,
     "Values": {
          "AzureWebJobsStorage": "",
          "FUNCTIONS_WORKER_RUNTIME": "dotnet",
          "EventHub": "",
          "CosmosDb": "",
         "ConfigurationConsumerGroup": "ActualConsumerGroup"
          }
        }

and changed code as below

       [FunctionName("device-message--funcapp-v2")]
    public static void Run([IoTHubTrigger("testhub", 
        Connection = "IoTHubEventEndPoint", 
        ConsumerGroup = "ConfigurationConsumerGroup")]EventData message, 
        ILogger log)

But it fails.

[1/18/2019 9:47:11 AM] Microsoft.Azure.EventHubs: The messaging entity 'iothub-ns-testhub-945897-3a6f492cc4:eventhub:lctesthub~8191|ConfigurationConsumerGroup' could not be found.

Answer 1

Use ConsumerGroup = "%ConfigurationConsumerGroup%" to read settings from local.settings.json. Check the doc. Note that the connection property of triggers and bindings is a special case and automatically resolves values as app settings, without percent signs.