Initial QSfera import

Server/pkg/middleware/tracing.go

@@ -0,0 +1,21 @@
+package middleware
+
+import (
+	"net/http"
+
+	"go.opentelemetry.io/otel/propagation"
+)
+
+var propagator = propagation.NewCompositeTextMapPropagator(
+	propagation.Baggage{},
+	propagation.TraceContext{},
+)
+
+// TraceContext unpacks the request context looking for an existing trace id.
+func TraceContext(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := propagator.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
+		propagator.Inject(ctx, propagation.HeaderCarrier(r.Header))
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}