Migrate to opentelemetry

pkg/middlewares/tracing/middleware.go

@@ -0,0 +1,71 @@
+package tracing
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/containous/alice"
+	"github.com/rs/zerolog/log"
+	"github.com/traefik/traefik/v3/pkg/logs"
+	"github.com/traefik/traefik/v3/pkg/tracing"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// Traceable embeds tracing information.
+type Traceable interface {
+	GetTracingInformation() (name string, typeName string, spanKind trace.SpanKind)
+}
+
+// WrapMiddleware adds traceability to an alice.Constructor.
+func WrapMiddleware(ctx context.Context, constructor alice.Constructor) alice.Constructor {
+	return func(next http.Handler) (http.Handler, error) {
+		if constructor == nil {
+			return nil, nil
+		}
+		handler, err := constructor(next)
+		if err != nil {
+			return nil, err
+		}
+
+		if traceableHandler, ok := handler.(Traceable); ok {
+			name, typeName, spanKind := traceableHandler.GetTracingInformation()
+			log.Ctx(ctx).Debug().Str(logs.MiddlewareName, name).Msg("Adding tracing to middleware")
+			return NewMiddleware(handler, name, typeName, spanKind), nil
+		}
+		return handler, nil
+	}
+}
+
+// NewMiddleware returns a http.Handler struct.
+func NewMiddleware(next http.Handler, name string, typeName string, spanKind trace.SpanKind) http.Handler {
+	return &middlewareTracing{
+		next:     next,
+		name:     name,
+		typeName: typeName,
+		spanKind: spanKind,
+	}
+}
+
+// middlewareTracing is used to wrap http handler middleware.
+type middlewareTracing struct {
+	next     http.Handler
+	name     string
+	typeName string
+	spanKind trace.SpanKind
+}
+
+func (w *middlewareTracing) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	if tracer := tracing.TracerFromContext(req.Context()); tracer != nil {
+		tracingCtx, span := tracer.Start(req.Context(), w.typeName, trace.WithSpanKind(w.spanKind))
+		defer span.End()
+
+		req = req.WithContext(tracingCtx)
+
+		span.SetAttributes(attribute.String("traefik.middleware.name", w.name))
+	}
+
+	if w.next != nil {
+		w.next.ServeHTTP(rw, req)
+	}
+}