# Create custom traces and metrics

> Custom traces and metrics using .NET automatic instrumentation.

---

The automatic instrumentation configures a `TracerProvider` and a
`MeterProvider` so that you can add your own manual instrumentation. By using
both automatic and manual instrumentation, you can better instrument the logic
and functionality of your applications, clients, and frameworks.

## Traces

To create your custom traces manually, follow these steps:

1. Add the `System.Diagnostics.DiagnosticSource` dependency to your project:

   ```xml
   <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="8.0.0" />
   ```

2. Create an `ActivitySource` instance:

   ```csharp
   private static readonly ActivitySource RegisteredActivity = new ActivitySource("Examples.ManualInstrumentations.Registered");
   ```

3. Create an `Activity`. Optionally, set tags:

   ```csharp
   using (var activity = RegisteredActivity.StartActivity("Main"))
   {
      activity?.SetTag("foo", "bar1");
      // your logic for Main activity
   }
   ```

4. Register your `ActivitySource` in OpenTelemetry.AutoInstrumentation by
   setting the `OTEL_DOTNET_AUTO_TRACES_ADDITIONAL_SOURCES` environmental
   variable. You can set the value to either
   `Examples.ManualInstrumentations.Registered` or to
   `Examples.ManualInstrumentations.*`, which registers the entire prefix.

> [!WARNING]
>
> An `Activity` created for `NonRegistered.ManualInstrumentations`
> `ActivitySource` is not handled by the OpenTelemetry Automatic
> Instrumentation.

## Metrics

To create your custom metrics manually, follow these steps:

1. Add the `System.Diagnostics.DiagnosticSource` dependency to your project:

   ```xml
   <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="8.0.0" />
   ```

2. Create a `Meter` instance:

   ```csharp
   using var meter = new Meter("Examples.Service", "1.0");
   ```

3. Create an `Instrument`:

   ```csharp
   var successCounter = meter.CreateCounter<long>("srv.successes.count", description: "Number of successful responses");
   ```

4. Update the `Instrument` value. Optionally, set tags:

   ```csharp
   successCounter.Add(1, new KeyValuePair<string, object?>("tagName", "tagValue"));
   ```

5. Register your `Meter` with OpenTelemetry.AutoInstrumentation by setting the
   `OTEL_DOTNET_AUTO_METRICS_ADDITIONAL_SOURCES` environment variable:

   ```bash
   OTEL_DOTNET_AUTO_METRICS_ADDITIONAL_SOURCES=Examples.Service
   ```

   You can set the value to either `Examples.Service` or to `Examples.*`, which
   registers the entire prefix.

## Further reading

- [OpenTelemetry.io documentation for .NET Manual Instrumentation](/docs/languages/dotnet/instrumentation#setting-up-an-activitysource)