How to setup OpenTelemetry instrumentation in ASP.NET core

In this post I’ll show how to setup OpenTelemetry tracing, metrics and logging for AspNetCore on dotnet 6

New project

Start by creating a new project. I’ll be using the webapi template.

dotnet new webapi --output opentelemetry-example

Add required packages

Then we need to add the OpenTelemetry packages.

dotnet add package --prerelease OpenTelemetry.Exporter.Console
dotnet add package --prerelease OpenTelemetry.Extensions.Hosting
dotnet add package --prerelease OpenTelemetry.Instrumentation.AspNetCore

The first package is the console exporter which is for outputing telemetry data on to your local developer console. For a real project you would probably use something like the jaeger or the otlp exporter.

The Extension.Hosting package includes the extension methods AddOpenTelemetryTracing and AddOpenTelemetryMetrics which is used on IServiceCollectionto setup OpenTelemetry. It also adds the LoggingBuilder extension method AddOpenTelemetry.

The Instrumentation.AspNetCore package collects telemetry data about incoming web requests. It provides the AddAspNetCoreInstrumentation extension method for TraceProviderBuilder and MeterProviderBuilder

Add tracing

builder.Services
    .AddOpenTelemetryTracing((builder) => builder
        // Configure the resource attribute `service.name` to MyServiceName
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MyServiceName"))
        // Add tracing of the AspNetCore instrumentation library
        .AddAspNetCoreInstrumentation()
        .AddConsoleExporter()
    );

Add metrics

builder.Services
    .AddOpenTelemetryMetrics(builder => builder
        // Configure the resource attribute `service.name` to MyServiceName
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MyServiceName"))
        // Add metrics from the AspNetCore instrumentation library
        .AddAspNetCoreInstrumentation()
        .AddConsoleExporter(options =>
        {
            options.MetricReaderType = MetricReaderType.Periodic;
            options.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 5000;
        }));

Add logging

builder.Host
    .ConfigureLogging(logging => logging
        .ClearProviders()
        .AddOpenTelemetry(options =>
        {
            // Export the body of the message
            options.IncludeFormattedMessage = true;
            // Configure the resource attribute `service.name` to MyServiceName
            options.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MyServiceName"));
            options.AddConsoleExporter(options =>
            {
                options.MetricReaderType = MetricReaderType.Periodic;
                options.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 5000;
            });
        }));

Complete example

using OpenTelemetry.Logs;
using OpenTelemetry.Metrics;
using OpenTelemetry.Resources;
using OpenTelemetry.Trace;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

builder.Services
    .AddOpenTelemetryTracing((builder) => builder
        // Configure the resource attribute `service.name` to MyServiceName
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MyServiceName"))
        // Add tracing of the AspNetCore instrumentation library
        .AddAspNetCoreInstrumentation()
        .AddConsoleExporter()
    );

builder.Services
    .AddOpenTelemetryMetrics(builder => builder
        // Configure the resource attribute `service.name` to MyServiceName
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MyServiceName"))
        // Add metrics from the AspNetCore instrumentation library
        .AddAspNetCoreInstrumentation()
        .AddConsoleExporter(options =>
        {
            options.MetricReaderType = MetricReaderType.Periodic;
            options.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 5000;
        }));

builder.Host
    .ConfigureLogging(logging => logging
        .ClearProviders()
        .AddOpenTelemetry(options =>
        {
            // Export the body of the message
            options.IncludeFormattedMessage = true;
            // Configure the resource attribute `service.name` to MyServiceName
            options.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService("MyServiceName"));
            options.AddConsoleExporter(options =>
            {
                options.MetricReaderType = MetricReaderType.Periodic;
                options.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 5000;
            });
        }));


var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();