# .NET

Instrument .NET applications with OpenTelemetry

# Integration

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)**