跳转至

Using instrumentation libraries

You can use instrumentation libraries in order to generate telemetry data for a particular instrumented library.

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:

1
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 package 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:

1
2
3
dotnet add package OpenTelemetry
dotnet add package OpenTelemetry.Extensions.Hosting
dotnet add package OpenTelemetry.Exporter.Console

Then you can install the Instrumentation packages

1
2
dotnet add package OpenTelemetry.Instrumentation.AspNetCore --prerelease
dotnet add package OpenTelemetry.Instrumentation.Http --prerelease

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

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
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 manual instrumentation 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.