Adding Opentelemetry to .Net Core worker service

Question

I am trying to add opentelemetry to one of my .net core 5.0 worker service project everything works ok but the traces are not begin sent to the Jaeger UI, I also notice the ActivitySource.StartActivity return null, I searched on google and looks like I might be missing the ActivirtListner but not sure how to add to my worker service,

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureServices((hostContext, services) =>
        {
            services.AddHostedService();
            services.AddOpenTelemetryTracing(builder =>
            {
                //IConfiguration config = sp.GetRequiredService();
                builder
                    //.SetSampler(new AlwaysOnSampler())
                    .AddHttpClientInstrumentation()
                    //.AddSqlClientInstrumentation()
                    //.AddNServiceBusInstrumentation()
                    //.AddRabbitMqInstrumentation()
                    .AddSource(nameof(Worker))
                    .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("WorkerServiceForTelemetry"))
                    .AddConsoleExporter()
                    .AddAspNetCoreInstrumentation()
                    //.AddOtlpExporter(options => options.Endpoint = new Uri("http://localhost:4317"))
                    .AddJaegerExporter(opts =>
                    {
                        opts.AgentHost = "Jaeger";
                        opts.AgentPort = 6831;
                        opts.ExportProcessorType = ExportProcessorType.Simple;
                    });
            });
        }

here is my worker.cs file

using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using MessageType;
using PublishToRabbitMq;
using System.Diagnostics;
using OpenTelemetry.Context.Propagation;

namespace WorkerServiceForTelemetry
{
    public class Worker : BackgroundService
    {
        private readonly ILogger _logger;
        private static readonly ActivitySource _activity = new(nameof(Worker));
        private static readonly TextMapPropagator Propagator = Propagators.DefaultTextMapPropagator;

        public Worker(ILogger logger)
        {
            _logger = logger;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            //using (var sample = new InstrumentationWithActivitySource())
            //{
            //    sample.Start();
            //    System.Console.WriteLine("Traces are being created and exported" +
            //        "to Jaeger in the background. Use Jaeger to view them." +
            //        "Press ENTER to stop.");
            //    System.Console.ReadLine();
            //}

            while (!stoppingToken.IsCancellationRequested)
            {
                _logger.LogInformation("Worker running at: {time}", DateTimeOffset.Now);             
                DoWork();
                await Task.Delay(10000, stoppingToken);
            }
        }

        public void DoWork()
        {
            //using var listener = new ActivityListener
            //{
            //    ShouldListenTo = _ => true,
            //    Sample = (ref ActivityCreationOptions _) => ActivitySamplingResult.AllData,
            //    ActivityStarted = activity => Console.WriteLine($"{activity.ParentId}:{activity.Id} - Start"),
            //    ActivityStopped = activity => Console.WriteLine($"{activity.ParentId}:{activity.Id} - Stop")
            //};

            //ActivitySource.AddActivityListener(listener);

            //var parentContext = Propagator.Extract(default,
            //        ea.BasicProperties,
            //        ActivityHelper.ExtractTraceContextFromBasicProperties);

            //Baggage.Current = parentContext.Baggage;
            Console.WriteLine("this is WorkerServiceForTelemetry is running");
            Console.WriteLine("Publish Message");
            Publish publish = new Publish();
            var context = Activity.Current?.Context;
            for (var i=0; i<=1; i++)
            {
                using (var activity = _activity.StartActivity("RabbitMq Publish", ActivityKind.Server))
                {
                    PersonName person = new PersonName();
                    person.FirstName = "Zafar" + i;
                    person.LastName = "Jamal" + i;
                    publish.SendMessage(person);
                }
            }
        }
    }
}

user_952050 · Answer

If you place a breakpoint inside the using block where you're starting the activity, you'll probably notice that StartActivity method is returning a null. This is because no listener got added to the ActivitySource.

Replace

ActivitySource.AddActivityListener(listener);

with

ActivitySource.AddActivityListener(new ActivityListener()
{
    ShouldListenTo = _ => true,
    Sample = (ref ActivityCreationOptions _) => ActivitySamplingResult.AllData,
    ActivityStarted = activity => Console.WriteLine($"{activity.ParentId}:{activity.Id} - Start"),
    ActivityStopped = activity => Console.WriteLine($"{activity.ParentId}:{activity.Id} - Stop")
});

and then try

user_3232646 · Answer

There is a lot of commented code in your question which makes it a bit difficult to analyze. But it seems like you are missing starting the host after its creation, which is required for tracing provider:

Host
    .CreateDefaultBuilder(args)
    .ConfigureServices((_, services) =>
    {
        ...
        services.AddOpenTelemetryTracing(builder =>
        {
            ...
            builder.AddSource("example");
            builder.AddConsoleExporter();
        });
    })
    .Build()
    .Start();

You can do an equivalent thing fashion using Sdk.CreateTracerProviderBuilder():

Sdk
    .CreateTracerProviderBuilder()
    .AddConsoleExporter()
    .AddSource("example")
    .Build();

Adding Opentelemetry to .Net Core worker service

2 Answers