Semconv OTLP stable HTTP metrics

pkg/middlewares/observability/router.go

@@ -0,0 +1,60 @@
+package observability
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/containous/alice"
+	"github.com/traefik/traefik/v3/pkg/logs"
+	"github.com/traefik/traefik/v3/pkg/middlewares"
+	"github.com/traefik/traefik/v3/pkg/tracing"
+	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
+	"go.opentelemetry.io/otel/trace"
+)
+
+const (
+	routerTypeName = "TracingRouter"
+)
+
+type routerTracing struct {
+	router     string
+	routerRule string
+	service    string
+	next       http.Handler
+}
+
+// WrapRouterHandler Wraps tracing to alice.Constructor.
+func WrapRouterHandler(ctx context.Context, router, routerRule, service string) alice.Constructor {
+	return func(next http.Handler) (http.Handler, error) {
+		return newRouter(ctx, router, routerRule, service, next), nil
+	}
+}
+
+// newRouter creates a new tracing middleware that traces the internal requests.
+func newRouter(ctx context.Context, router, routerRule, service string, next http.Handler) http.Handler {
+	middlewares.GetLogger(ctx, "tracing", routerTypeName).
+		Debug().Str(logs.RouterName, router).Str(logs.ServiceName, service).Msg("Added outgoing tracing middleware")
+
+	return &routerTracing{
+		router:     router,
+		routerRule: routerRule,
+		service:    service,
+		next:       next,
+	}
+}
+
+func (f *routerTracing) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	if tracer := tracing.TracerFromContext(req.Context()); tracer != nil {
+		tracingCtx, span := tracer.Start(req.Context(), "Router", trace.WithSpanKind(trace.SpanKindInternal))
+		defer span.End()
+
+		req = req.WithContext(tracingCtx)
+
+		span.SetAttributes(attribute.String("traefik.service.name", f.service))
+		span.SetAttributes(attribute.String("traefik.router.name", f.router))
+		span.SetAttributes(semconv.HTTPRoute(f.routerRule))
+	}
+
+	f.next.ServeHTTP(rw, req)
+}