HotROD external baggage

tracing.go

func (tm *TracedServeMux) AddHandler(pattern string, handler http.Handler) {
	middleware := nethttp.Middleware(tm.tracer, handler,
		nethttp.MWSpanObserver(func(span opentracing.Span, r *http.Request) {
			if !tm.copyBaggage {
				return
			}
			bag := baggage.FromContext(r.Context())
			for _, m := range bag.Members() {
				span.SetBaggageItem(m.Key(), m.Value())
			}
		}),
	)
}

func otelBaggageExtractor(next http.Handler) http.Handler {
	propagator := propagation.Baggage{}
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		carrier := propagation.HeaderCarrier(r.Header)
		ctx := propagator.Extract(r.Context(), carrier)
		r = r.WithContext(ctx)
		next.ServeHTTP(w, r)
	})
}