Azure - Debugging Iot Hub - Function trigger - azure

Question

I'm trying to get the payload of Azure IoT Hub telemetry to a Function. I tried using this documentation, but I must be missing something. While I see data coming through, my function is not executed. I tried to put a Service Bus in between, so I created a Message Route in my IoT Hub and used that according to the same documentation, but for Service Bus instead of IoT Hub. I see the messages from a simulated device in the IoT Hub and the Service Bus, but somehow, the function is not executed. I also have no idea how to debug this problem, why the function is not executed. Any help with debugging tips or documentation tips would be much appreciated.
I added the Service Bus parameters in host.json:
...
"serviceBus": {
"prefetchCount": 100,
"messageHandlerOptions": {
"autoComplete": true,
"maxConcurrentCalls": 32,
"maxAutoRenewDuration": "00:05:00"
},
"sessionHandlerOptions": {
"autoComplete": false,
"messageWaitTimeout": "00:00:30",
"maxAutoRenewDuration": "00:55:00",
"maxConcurrentSessions": 16
},
"batchOptions": {
"maxMessageCount": 1000,
"operationTimeout": "00:01:00",
"autoComplete": true
}
}
...
And set the right trigger binding in functions.json:
{
"scriptFile": "__init__.py",
"bindings": [
{
"name": "msg",
"type": "serviceBusTrigger",
"direction": "in",
"queueName": "[MyQueueName]",
"connection": "Endpoint=sb://[MyServiceBusName].servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=[MyServiceBusSAS]"
}
]
}

Answer 1

So what the instructions lack to tell you, what I did wrong, is that you should give your connection an arbitrary name, say queue_conn_str. Then on the Azure Portal, you go to your function app, and set there the application setting with the actual connection string (Endpoint...), with the same name (queue_conn_str).
With that you can actually connect your IoT hub directly to your function, no need for an Event Hub or Service Bus in between.