Where to find custom metrics in Azure Portal

Question

I'm trying to send custom metrics to an App Service in Azure Portal given an instrumentation key. I have the following code running in .NET Core as part of a Background service:

public override async Task StartAsync(CancellationToken stoppingToken)
{
    try
    {
        TelemetryClient telemetry = new TelemetryClient();
        telemetry.TrackEvent("new event");
        var sample = new MetricTelemetry();
        sample.Name = "metric name";
        sample.Value = 42.3;
        telemetry.TrackMetric(sample);
        telemetry.Flush();
    }
    catch (Exception e)
    {
        _logger.LogError($"{e.Message} {e.StackTrace}");
    }
}

This sample code comes from here.

However I'm not sure if these metrics are even reaching the Azure instance or where to look for them. I went to Application Insights > MyInstance > Logs and found a table there named 'customEvents'. However I can't query over it. On the Metrics tabs I only get the default metrics namespace which shows the default metrics available in Azure, but not any new custom metrics.

Answer 1

I think the issue is that you create a new telemetry client by using this line of code: TelemetryClient telemetry = new TelemetryClient();, but the new telemetry client does not configure a InstrumentationKey. Then the custom events / custom metrics are not sent by using telemetry.TrackEvent / telemetry.TrackMetric methods.

You should change it like below in Worker.cs:

namespace WorkerService3
{
    public class Worker : BackgroundService
    {
        private readonly ILogger<Worker> _logger;

        //define a telemetry client here, and use it in your following code
        private TelemetryClient telemetry;

        public Worker(ILogger<Worker> logger, TelemetryClient tc)
        {
            _logger = logger;
            telemetry = tc;
        }

        public override async Task StartAsync(CancellationToken stoppingToken)
        {
            try
            {
                //do not create a another telemetry client, use the one defined in class-level.
                //TelemetryClient telemetry = new TelemetryClient();
                telemetry.TrackTrace("StartAsync: new message");
                telemetry.TrackEvent("StartAsync: new event");
                var sample = new MetricTelemetry();
                sample.Name = "StartAsync metric name";
                sample.Value = 11.55;
                telemetry.TrackMetric(sample);
                telemetry.Flush();
            }
            catch (Exception e)
            {
                _logger.LogError($"{e.Message} {e.StackTrace}");
            }

        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
           //other code
        }
    }
}

And this is my Program.cs:

namespace WorkerService3
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureServices((hostContext, services) =>
                {
                    services.AddHostedService<Worker>();
                    services.AddApplicationInsightsTelemetryWorkerService();
                });
    }
}

This is my appsettings.json:

{
  "ApplicationInsights": {
    "InstrumentationKey": "your application insights InstrumentationKey"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  }
}

After the code is executed, wait for a few minutes, I can search custom metrics / custom events in azure portal -> my application insights -> Logs(for custom events, query the customEvents table):