func initTracer() func(context.Context) error {

   secureOption := otlptracegrpc.WithTLSCredentials(credentials.NewClientTLSFromCert(nil, ""))
   if len(insecure) > 0 {
      secureOption = otlptracegrpc.WithInsecure()
   }

   exporter, err := stdouttrace.New(stdouttrace.WithPrettyPrint())
   if err != nil {
      log.Fatalf("failed to initialize stdout export pipeline: %v", err)
   }

   tracer, err := otlptrace.New(
      context.Background(),
      otlptracegrpc.NewClient(
         secureOption,
         otlptracegrpc.WithEndpoint(collectorURL),
      ),
   )

   if err != nil {
      log.Fatal(err)
   }
   resources, err := resource.New(
      context.Background(),
      resource.WithAttributes(
         attribute.String("service.name", serviceName),
         attribute.String("library.language", "go"),
      ),
   )
   if err != nil {
      log.Println("Could not set resources: ", err)
   }

   otel.SetTracerProvider(
      sdktrace.NewTracerProvider(
         sdktrace.WithSampler(sdktrace.AlwaysSample()),
         sdktrace.WithBatcher(tracer),
         sdktrace.WithBatcher(exporter),
         sdktrace.WithResource(resources),
      ),
   )

   return tracer.Shutdown
}