> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apitally.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Tracing instrumentation

> Instrument your .NET application for tracing in Apitally.

When tracing is enabled, the Apitally SDK captures [Activities](https://learn.microsoft.com/en-us/dotnet/core/diagnostics/distributed-tracing-concepts) during request handling and attaches them to request logs. This allows you to see exactly what happened during each request, including database queries, HTTP calls to external services, and custom operations.

The SDK uses the native `System.Diagnostics.Activity` API, which is the same API that [OpenTelemetry for .NET](https://opentelemetry.io/docs/languages/dotnet/) is built on. This means OpenTelemetry is not required, but any existing OpenTelemetry instrumentation will work seamlessly.

## Enable tracing

To enable tracing, set `CaptureTraces` to `true` in your request logging configuration:

<CodeGroup>
  ```csharp Program.cs {5-6} theme={null}
  builder.Services.AddApitally(options =>
  {
      options.ClientId = "your-client-id";
      options.Env = "dev";
      options.RequestLogging.Enabled = true;
      options.RequestLogging.CaptureTraces = true;
  });
  ```

  ```json appsettings.json {6-7} theme={null}
  {
    "Apitally": {
      "ClientId": "your-client-id",
      "Env": "dev",
      "RequestLogging": {
        "Enabled": true,
        "CaptureTraces": true
      }
    }
  }
  ```
</CodeGroup>

## Instrument libraries

`HttpClient` and some other .NET libraries include built-in Activity instrumentation, so they generate spans automatically without any additional setup.

Other libraries require OpenTelemetry instrumentation packages. For example:

| Library               | Instrumentation package                                                                                                                 |
| :-------------------- | :-------------------------------------------------------------------------------------------------------------------------------------- |
| Entity Framework Core | [`OpenTelemetry.Instrumentation.EntityFrameworkCore`](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.EntityFrameworkCore) |
| SqlClient             | [`OpenTelemetry.Instrumentation.SqlClient`](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.SqlClient)                     |
| Npgsql                | [`Npgsql.OpenTelemetry`](https://www.nuget.org/packages/Npgsql.OpenTelemetry)                                                           |
| StackExchange.Redis   | [`OpenTelemetry.Instrumentation.StackExchangeRedis`](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.StackExchangeRedis)   |

See the [OpenTelemetry registry](https://opentelemetry.io/ecosystem/registry/?language=dotnet\&component=instrumentation) for more instrumentation packages.

## Create custom spans

For custom operations that aren't covered by library instrumentation, you can create spans manually using the `System.Diagnostics` API.

First, create an `ActivitySource` for your application (typically as a static field):

```csharp theme={null}
using System.Diagnostics;

public static class Telemetry
{
    public static readonly ActivitySource Source = new("MyApp");
}
```

Then use `StartActivity` to create spans:

```csharp theme={null}
public async Task ProcessOrderAsync(int orderId)
{
    using var activity = Telemetry.Source.StartActivity("ProcessOrder");
    activity?.SetTag("order.id", orderId);

    // ...
}
```