Adding Custom Dimension to Request Telemetry - Azure functions

Question

I am creating a new Function app using v2.x and I am integrating Application Insights for request logging that is automatically being done as Azure Function is now integrated with App Insights (as mentioned in the documentation link). What I would need to do is log few custom fields in the custom dimensions in Application Insights Request Telemetry. Is it possible without using Custom Request logging (using TrackRequest method)

Answer 1

You should use ITelemetry Initializer(which can add custom dimension to a specified telemetry like only for request) in function app, please follow the steps below:

1.In Visual studio, create a function app(In my test, I create a blob triggerd function), and install the following nuget packages:

Microsoft.ApplicationInsights, version 2.10.0

Microsoft.NET.Sdk.Functions, version 1.0.29

2.Then in the Function1.cs, write code like below:

using Microsoft.ApplicationInsights.Channel;
using Microsoft.ApplicationInsights.DataContracts;
using Microsoft.ApplicationInsights.Extensibility;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System.IO;

[assembly: WebJobsStartup(typeof(FunctionApp21.MyStartup))]
namespace FunctionApp21
{
    public static class Function1
    {


        [FunctionName("Function1")]
        public static void Run([BlobTrigger("samples-workitems/{name}", Connection = "AzureWebJobsStorage")]Stream myBlob, string name, ILogger log)
        {
            log.LogInformation($"C# Blob trigger function Processed blob\n Name:{name} \n Size: {myBlob.Length} Bytes");
        }
    }

    internal class MyTelemetryInitializer : ITelemetryInitializer
    {
        public void Initialize(ITelemetry telemetry)
        {           

            //use telemetry is RequestTelemetry to make sure only add to request
            if (telemetry != null && telemetry is RequestTelemetry && !telemetry.Context.GlobalProperties.ContainsKey("my_custom_dimen22"))
            {
                telemetry.Context.GlobalProperties.Add("my_custom_dimen22", "Hello, this is custom dimension for request!!!");
            }
        }
    }

    public class MyStartup : IWebJobsStartup
    {
        public void Configure(IWebJobsBuilder builder)
        {
            builder.Services.AddSingleton<ITelemetryInitializer, MyTelemetryInitializer>();

        }
    }
}

3.Publish it to azure, then nav to azure portal -> the published function app -> Monitor -> Add an application insights.

4.Run the function from azure. And wait for a few minutes -> nav to the application insights portal, check the telemetry data, and you can see the custom dimension is only added to request telemetry: