handler-with-producer.go

func handler(c *gin.Context) {
	tracer := otel.GetTracerProvider().Tracer("gin-hander")
	ctx, span := tracer.Start(c.Request.Context(), "handler-span")
	defer span.End()

	fmt.Println(c.Request.Header)

	rand.Seed(time.Now().Unix())
	msg := sarama.ProducerMessage{
		Topic: "example-topic",
		Key:   sarama.StringEncoder("random_number"),
		Value: sarama.StringEncoder(fmt.Sprintf("%d", rand.Intn(1000))),
	}
	otel.GetTextMapPropagator().Inject(ctx, otelsarama.NewProducerMessageCarrier(&msg))

	producer.Input() <- &msg
	successMsg := <-producer.Successes()
	fmt.Println("Successful to write message, offset:", successMsg.Offset)

	c.JSON(http.StatusOK, gin.H{
		"message": http.StatusText(http.StatusOK),
	})
}