OpenTelemetry tracer provider with ratio-based sampling

                  package observability

import (
  "context"

  "go.opentelemetry.io/otel"
  "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
  "go.opentelemetry.io/otel/propagation"
  "go.opentelemetry.io/otel/sdk/resource"
  sdktrace "go.opentelemetry.io/otel/sdk/trace"
  semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
)

func InitTracing(ctx context.Context, serviceName string) (*sdktrace.TracerProvider, error) {
  exp, err := otlptracegrpc.New(ctx)
  if err != nil {
    return nil, err
  }
  res, err := resource.New(ctx, resource.WithAttributes(semconv.ServiceName(serviceName)))
  if err != nil {
    return nil, err
  }

  tp := sdktrace.NewTracerProvider(
    sdktrace.WithBatcher(exp),
    sdktrace.WithResource(res),
    sdktrace.WithSampler(sdktrace.ParentBased(sdktrace.TraceIDRatioBased(0.1))),
  )

  otel.SetTracerProvider(tp)
  otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
  return tp, nil
}