Program.cs

using OpenTelemetry.Resources;
using OpenTelemetry.Trace;
using OpenTelemetry.Logs;
using OpenTelemetry.Exporter;

var builder = WebApplication.CreateBuilder(args);

const string telemetrySourceName = "honeycomb.examples.year-service-dotnet";

var resourceBuilder = ResourceBuilder.CreateDefault()
    .AddService(builder.Configuration.GetValue<string>("Otlp:ServiceName"))
    .AddEnvironmentVariableDetector();

var configureOtlpExporter = (OtlpExporterOptions options) =>
{
    options.Endpoint = new Uri(builder.Configuration.GetValue<string>("Otlp:Endpoint"));
    var apiKey = builder.Configuration.GetValue<string>("Otlp:ApiKey");
    var dataset = builder.Configuration.GetValue<string>("Otlp:Dataset");
    options.Headers = $"x-honeycomb-team={apiKey},x-honeycomb-dataset={dataset}";
};

builder.Services.AddOpenTelemetry()
    .WithTracing(options => options
        .SetResourceBuilder(resourceBuilder)
        .AddSource(telemetrySourceName)
        .AddAspNetCoreInstrumentation()
        .AddHttpClientInstrumentation()
        .AddOtlpExporter(configureOtlpExporter));

builder.Logging.AddOpenTelemetry(options => options
    .SetResourceBuilder(resourceBuilder)
    .AddOtlpExporter(configureOtlpExporter)
);

Tracer tracer = TracerProvider.Default.GetTracer(telemetrySourceName);
var app = builder.Build();
int[] years = { 2015, 2016, 2017, 2018, 2019, 2020 };

app.MapGet("/year", () =>
{
    using var span = tracer.StartActiveSpan("🗓 get-a-year ✨");
    span.SetAttribute("banana", 1);
    var rng = new Random();
    var i = rng.Next(years.Length - 1);
    var year = years[i];
    app.Logger.LogInformation($"Selected year: ${year}");
    return year;
});

app.Run();