Azure Functions with IoT Hub

Question

I am asking myself whether it is a good idea to have an Azure Function consuming events directly from the EventHub compatible IoT Hub endpoint.

According to this answer Azure Functions use EventHubProcessorHost to consume the events. It also indicates that if a Function seems sluggish the scaling logic kicks in and creates more instances of a Function (e.g. per IoT Hub partition).

What is the trigger for the scaling logic? Number of unprocessed messages? Processing duration of a single message (would not be a good metric)?

Thanks

Answer 1

The scaling logic looks at the total number of unprocessed messages remaining in all the partitions of the EventHub.