# Go

Instrument Go applications with OpenTelemetry

# Integration

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

## Installation

```bash
go get go.opentelemetry.io/otel
go get go.opentelemetry.io/otel/sdk
go get go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp
go get go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp
```

## Basic Setup

Initialize OpenTelemetry in your application:

```go
import (
    "context"

    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
    "go.opentelemetry.io/otel/sdk/resource"
    sdktrace "go.opentelemetry.io/otel/sdk/trace"
    semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
)

func initTracer(ctx context.Context) (*sdktrace.TracerProvider, error) {
    exporter, err := otlptracehttp.New(ctx)
    if err != nil {
        return nil, err
    }

    res, _ := resource.New(ctx,
        resource.WithAttributes(semconv.ServiceName("my-service")),
    )

    tp := sdktrace.NewTracerProvider(
        sdktrace.WithBatcher(exporter),
        sdktrace.WithResource(res),
    )
    otel.SetTracerProvider(tp)
    return tp, nil
}
```

The SDK reads the OTLP endpoint from standard OpenTelemetry environment variables.

## Running Your Application

Set the required environment variables and run:

```bash
export OTEL_EXPORTER_OTLP_ENDPOINT="https://otlp-http.kopai.app"
export OTEL_EXPORTER_OTLP_HEADERS="Authorization=Bearer YOUR_TOKEN"
export OTEL_SERVICE_NAME="my-service"
go run main.go
```

| Variable | Description |
|----------|-------------|
| `OTEL_EXPORTER_OTLP_ENDPOINT` | Kopai OTLP endpoint |
| `OTEL_EXPORTER_OTLP_HEADERS` | Auth header with your backend token |
| `OTEL_SERVICE_NAME` | Name shown in Kopai UI |

## Graceful Shutdown

Always shut down the tracer provider to flush remaining spans:

```go
defer func() {
    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()
    tp.Shutdown(ctx)
}()
```

## Working Example

For a complete working example:

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