Add Custom Properties for RequestTelemetry of the Azure Function (v3)

Question

I have a function app written in C# and deployed on Azure. In order to achieve correlation, I want to add some Custom Properties into the default RequestTelemetry of the Azure Function:

My function looks like as follow:

    [FunctionName("Upload")]
    [StorageAccount("AzureWebJobsStorage")]
    public static async Task<IActionResult> Upload(
        [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = "upload/{name}")] HttpRequest req,
        string name,
        ILogger log,
        ExecutionContext context)
    {       
      
        var requestTelemetry = req.HttpContext?.Features.Get<RequestTelemetry>();

        ....

        return new OkObjectResult(name + "Uploaded successfully.");
    }

According to my research, most people suggest using following code:

 requestTelemetry.Context.GlobalProperties.Add("someproperty", "123");

or

 // Deprecated
 requestTelemetry.Context.Properties.Add("someproperty", "123");

But it doesn't work.

So I wonder if it is even possible to modify the Custom Properties of the default RequestTelemetry in Azure Function(V3). Does anyone have other tips about how to achieve this?

Answer 1

There are some ways. One is like this:

var requestTelemetry = req.HttpContext.Features.Get<RequestTelemetry>();
requestTelemetry.Properties.Add("aProp", "aValue");

The other one is

Activity.Current.AddTag("aProp", "aValue");

I have a full working demo project in a personal repo found here that demonstrates the code in this answer.