Using instrumentation libraries

アプリを開発する際、作業を加速するためにサードパーティのライブラリやフレームワークを使用することがあるでしょう。 OpenTelemetryを使用してアプリを計装する場合、使用するサードパーティのライブラリやフレームワークにトレース、ログ、メトリクスを手動で追加するために時間を費やすことを避けたいことがあります。

多くのライブラリやフレームワークはすでにOpenTelemetryをサポートしているか、OpenTelemetryの計装を介してサポートされているため、テレメトリーを生成してオブザーバビリティバックエンドにエクスポートできます。

サードパーティのライブラリやフレームワークを使用しているアプリやサービスを計装する場合は、このページの手順に従って、ネイティブに計装されたライブラリと依存関係の計装ライブラリの使用方法を学んでください。

ネイティブに計装されたライブラリを使用する

デフォルトでOpenTelemetryサポートが付属しているライブラリの場合、アプリにOpenTelemetry SDKを追加して設定することで、そのライブラリから発行されるトレース、メトリクス、ログを取得できます。

ライブラリによっては、計装のために追加の構成が必要な場合があります。 詳細はライブラリごとのドキュメントをご覧ください。

• 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.