# .NET

Add OpenTelemetry to ASP.NET Core and export .NET traces, metrics and logs to Kopai. Wire it by hand, or leave it to your agent and the Kopai skills.

Instrument your .NET applications to send traces, logs, and metrics to Kopai.

## Installation

```bash
dotnet add package OpenTelemetry.Extensions.Hosting
dotnet add package OpenTelemetry.Instrumentation.AspNetCore
dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol
```

## Basic Setup

Add OpenTelemetry to your ASP.NET Core application:

```csharp
using OpenTelemetry.Exporter;
using OpenTelemetry.Logs;
using OpenTelemetry.Metrics;
using OpenTelemetry.Resources;
using OpenTelemetry.Trace;

var builder = WebApplication.CreateBuilder(args);

var endpoint = Environment.GetEnvironmentVariable("OTEL_EXPORTER_OTLP_ENDPOINT")
    ?? "http://localhost:4318";
var serviceName = Environment.GetEnvironmentVariable("OTEL_SERVICE_NAME")
    ?? "my-service";

// Setup Traces and Metrics
builder.Services.AddOpenTelemetry()
    .ConfigureResource(r => r.AddService(serviceName))
    .WithTracing(tracing => tracing
        .AddAspNetCoreInstrumentation()
        .AddOtlpExporter(opts =>
        {
            opts.Endpoint = new Uri($"{endpoint}/v1/traces");
            opts.Protocol = OtlpExportProtocol.HttpProtobuf;
        }))
    .WithMetrics(metrics => metrics
        .AddAspNetCoreInstrumentation()
        .AddOtlpExporter(opts =>
        {
            opts.Endpoint = new Uri($"{endpoint}/v1/metrics");
            opts.Protocol = OtlpExportProtocol.HttpProtobuf;
        }));

// Setup Logs
builder.Logging.AddOpenTelemetry(logging =>
{
    logging.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(serviceName));
    logging.AddOtlpExporter(opts =>
    {
        opts.Endpoint = new Uri($"{endpoint}/v1/logs");
        opts.Protocol = OtlpExportProtocol.HttpProtobuf;
    });
});
```

**Important**: Use `OtlpExportProtocol.HttpProtobuf` and append the signal path (`/v1/traces`, `/v1/logs`, `/v1/metrics`) to the endpoint.

## Running Your Application

Set the required environment variables and run:

```bash
export OTEL_EXPORTER_OTLP_ENDPOINT="https://otlp-http.kopai.app"
export OTEL_SERVICE_NAME="my-service"
dotnet run
```

| Variable | Description |
|----------|-------------|
| `OTEL_EXPORTER_OTLP_ENDPOINT` | Kopai OTLP endpoint |
| `OTEL_SERVICE_NAME` | Name shown in Kopai UI |

## Sending Headers

For authentication, add headers to the exporter:

```csharp
opts.Headers = "Authorization=Bearer YOUR_TOKEN";
```

## Working Example

For a complete working example:

**[.NET Example](https://github.com/kopai-app/kopai-integration-examples/tree/main/dotnet)**