Example telemetry listener which listens to Sockets, NameResolution, Http and Security events and counters

Program.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.Tracing;
using System.Net.Http;
using System.Threading.Tasks;

namespace TelemetryListener
{
    internal class Program
    {
        private static async Task Main()
        {
            using var listener = new TelemetryListener();

            var client = new HttpClient();

            try
            {
               await client.GetAsync("https://www.stevejgordon.co.uk");
            }
            catch
            {
                // ignore
            }

            await Task.Delay(2000);
        }
    }
    
    internal sealed class TelemetryListener : EventListener
    {
        protected override void OnEventSourceCreated(EventSource eventSource)
        {
            if (eventSource.Name.Equals("System.Net.Sockets") 
                || eventSource.Name.Equals("System.Net.Http")
                || eventSource.Name.Equals("System.Net.NameResolution")
                || eventSource.Name.Equals("System.Net.Security"))
            {
                EnableEvents(eventSource, EventLevel.Verbose, EventKeywords.All, new Dictionary<string, string>
                {
                    {"EventCounterIntervalSec", "2"}
                });
            }
        }

        protected override void OnEventWritten(EventWrittenEventArgs eventData)
        {
            if (eventData.EventName == "EventCounters")
            {
                if (eventData.Payload?.Count <= 0
                    || eventData.Payload?[0] is not IDictionary<string, object> data
                    || !data.TryGetValue("CounterType", out var ct)
                    || !data.TryGetValue("Name", out var n)
                    || ct is not string counterType
                    || n is not string name) return;

                var metricValue = counterType switch
                {
                    "Sum" when data.TryGetValue("Increment", out var increment) => Convert.ToInt64(increment),
                    "Mean" when data.TryGetValue("Mean", out var mean) => Convert.ToInt64(mean),
                    _ => 0
                };
                
                switch (nameString)
                {
                    case "dns-lookups-duration":
                        Console.WriteLine($"Event Counter = Avg Duration of Lookup: {metricValue}ms");
                        Console.WriteLine();
                        break;
                    case "dns-lookups-requested":
                        Console.WriteLine($"Event Counter = Name Resolution Lookups: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "total-tls-handshakes":
                        Console.WriteLine($"Event Counter = Total TLS Handshakes: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "requests-started":
                        Console.WriteLine($"Event Counter = HTTP Requests Started: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "requests-failed":
                        Console.WriteLine($"Event Counter = HTTP Requests Failed: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "outgoing-connections-established":
                        Console.WriteLine($"Event Counter = Outgoing Connections Established: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "http11-connections-current-total":
                        Console.WriteLine($"Event Counter = HTTP1.1 Connections Established: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "http20-connections-current-total":
                        Console.WriteLine($"Event Counter = HTTP2.0 Connections Established: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "bytes-sent":
                        Console.WriteLine($"Event Counter = Bytes Sent: {metricValue}");
                        Console.WriteLine();
                        break;
                    case "bytes-received":
                        Console.WriteLine($"Event Counter = Bytes Received: {metricValue}");
                        Console.WriteLine();
                        break;
                }
            }

            if (eventData.EventName != "EventCounters")
            {
                Console.WriteLine($"Event = {eventData.EventSource.Name} - {eventData.EventId}:{eventData.EventName}");

                for (var i = 0; i < eventData.PayloadNames?.Count; i++)
                {
                    Console.WriteLine(
                        $" - {eventData.PayloadNames[i]}: {eventData.Payload?[i]?.ToString() ?? string.Empty}");
                }
            }
        }
    }    
}