Using instrumentation libraries

Ao desenvolver uma aplicação, é possível utilizar bibliotecas e frameworks de terceiros para acelerar seu trabalho. Caso você instrumente sua aplicação utilizando OpenTelemetry, talvez queira evitar gastar tempo adicional para adicionar manualmente rastros, logs e métricas às bibliotecas e frameworks de terceiros que utiliza.

Muitas bibliotecas e frameworks já oferecem suporte ao OpenTelemetry ou são compatíveis por meio da instrumentação, permitindo gerar dados de telemetria que podem ser exportados para um backend de observabilidade.

Caso você esteja instrumentando uma aplicação ou serviço que utilize bibliotecas ou frameworks de terceiros, siga estas instruções para aprender como usar bibliotecas instrumentadas nativamente e bibliotecas de instrumentação para as dependências do seu projeto.

Usar bibliotecas com instrumentação nativa

Se uma biblioteca oferece suporte ao OpenTelemetry por padrão, é possível obter rastros, métricas e logs emitidos por essa biblioteca ao adicionar e configurar o SDK do OpenTelemetry na sua aplicação.

A biblioteca pode exigir alguma configuração adicional para sua instrumentação. Consulte a documentação dessa biblioteca para saber mais.

• Azure SDK Instrumentation
• MassTransit .NET client
• NServiceBus OpenTelemetry Integration
• ThrottlingTroll

Use Instrumentation Libraries

If a library does not come with OpenTelemetry out of the box, you can use instrumentation libraries in order to generate telemetry data for a library or framework.

For example, the instrumentation library for ASP.NET Core will automatically create spans and metrics based on the inbound HTTP requests.

Setup

Each instrumentation library is a NuGet package, and installing them is typically done like so:

dotnet add package OpenTelemetry.Instrumentation.{library-name-or-type}

It is typically then registered at application startup time, such as when creating a TracerProvider.

Note on Versioning

The Semantic Conventions (Standards) for attribute names are not currently stable therefore the instrumentation library is currently not in a released state. That doesn’t mean that the functionality itself is not stable, only that the names of some of the attributes may change in the future, some may be added, some may be removed. This means that you need to use the --prerelease flag, or install a specific version of the package

Example with ASP.NET Core and HttpClient

As an example, here’s how you can instrument inbound and output requests from an ASP.NET Core app.

First, get the appropriate packages of OpenTelemetry Core:

dotnet add package OpenTelemetry
dotnet add package OpenTelemetry.Extensions.Hosting
dotnet add package OpenTelemetry.Exporter.Console

Then you can install the instrumentation libraries:

dotnet add package OpenTelemetry.Instrumentation.AspNetCore --prerelease
dotnet add package OpenTelemetry.Instrumentation.Http --prerelease

Next, configure each instrumentation library at startup and use them!

using OpenTelemetry.Resources;
using OpenTelemetry.Trace;


var builder = WebApplication.CreateBuilder(args);

builder.Services.AddOpenTelemetry()
  .WithTracing(b =>
  {
      b
      .AddHttpClientInstrumentation()
      .AddAspNetCoreInstrumentation();
  });

var app = builder.Build();

var httpClient = new HttpClient();

app.MapGet("/hello", async () =>
{
    var html = await httpClient.GetStringAsync("https://example.com/");
    if (string.IsNullOrWhiteSpace(html))
    {
        return "Hello, World!";
    }
    else
    {
        return "Hello, World!";
    }
});

app.Run();

When you run this code and access the /hello endpoint, the instrumentation libraries will:

• Start a new trace
• Generate a span representing the request made to the endpoint
• Generate a child span representing the HTTP GET made to https://example.com/

If you add more instrumentation libraries, then you get more spans for each of those.

Available instrumentation libraries

A full list of instrumentation libraries produced by OpenTelemetry is available from the opentelemetry-dotnet repository.

You can also find more instrumentations available in the registry.

Next steps

After you have set up instrumentation libraries, you may want to add your own instrumentation to your code, to collect custom telemetry data.

If you are using .NET Framework 4.x instead of modern .NET, refer to the .NET Framework docs to configure OpenTelemetry and instrumentation libraries on .NET Framework.

You’ll also want to configure an appropriate exporter to export your telemetry data to one or more telemetry backends.

You can also check the automatic instrumentation for .NET, which is currently in beta.