Using Azure Function as output for Stream Analytics: Connection Test Fails

Question

I have an Azure Stream Analytics Job that uses an Azure Function as output. I deploy the ASA job as well as the function via CI/CD. When I deploy the ASA Job (given that the AF exists) the deployment succeeds and the job starts successfully. Furthermore the AF gets triggered successfully (i.e. the output works and it is not a problem e.g. related to the TSL setting -> Connection Test Failed when trying to add an Azure function as an output sink to Stream Analytics Job).

Still, when I am doing the connection test it fails:

Why is the connection test failing?

Answer 1

When testing the health of the connection an empty batch is send from ASA to the AF. The issue was that I was handling empty batches in way, that returned a 500 response what in the end caused the connection test to fail.

To avoid this issue it was necessary to implement another way of handling empty batches:

// Get and deserialize input content
string content = await req.Content.ReadAsStringAsync();
dynamic asaInput = JsonConvert.DeserializeObject(content);

// Handle empty input
if (asaInput is null || asaInput.Count == 0)
{
    log.Info("Received an empty request body...");
    return req.CreateResponse(HttpStatusCode.NoContent);
}