Introduce a fast proxy mode to improve HTTP/1.1 performances with backends

Co-authored-by: Romain <rtribotte@users.noreply.github.com>
Co-authored-by: Julien Salleyron <julien.salleyron@gmail.com>

pkg/proxy/httputil/observability.go

@@ -0,0 +1,105 @@
+package httputil
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/traefik/traefik/v3/pkg/metrics"
+	"github.com/traefik/traefik/v3/pkg/middlewares/observability"
+	"github.com/traefik/traefik/v3/pkg/tracing"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
+	"go.opentelemetry.io/otel/trace"
+)
+
+type wrapper struct {
+	semConvMetricRegistry *metrics.SemConvMetricsRegistry
+	rt                    http.RoundTripper
+}
+
+func newObservabilityRoundTripper(semConvMetricRegistry *metrics.SemConvMetricsRegistry, rt http.RoundTripper) http.RoundTripper {
+	return &wrapper{
+		semConvMetricRegistry: semConvMetricRegistry,
+		rt:                    rt,
+	}
+}
+
+func (t *wrapper) RoundTrip(req *http.Request) (*http.Response, error) {
+	start := time.Now()
+	var span trace.Span
+	var tracingCtx context.Context
+	var tracer *tracing.Tracer
+	if tracer = tracing.TracerFromContext(req.Context()); tracer != nil {
+		tracingCtx, span = tracer.Start(req.Context(), "ReverseProxy", trace.WithSpanKind(trace.SpanKindClient))
+		defer span.End()
+
+		req = req.WithContext(tracingCtx)
+
+		tracer.CaptureClientRequest(span, req)
+		tracing.InjectContextIntoCarrier(req)
+	}
+
+	var statusCode int
+	var headers http.Header
+	response, err := t.rt.RoundTrip(req)
+	if err != nil {
+		statusCode = ComputeStatusCode(err)
+	}
+	if response != nil {
+		statusCode = response.StatusCode
+		headers = response.Header
+	}
+
+	if tracer != nil {
+		tracer.CaptureResponse(span, headers, statusCode, trace.SpanKindClient)
+	}
+
+	end := time.Now()
+
+	// Ending the span as soon as the response is handled because we want to use the same end time for the trace and the metric.
+	// If any errors happen earlier, this span will be close by the defer instruction.
+	if span != nil {
+		span.End(trace.WithTimestamp(end))
+	}
+
+	if t.semConvMetricRegistry != nil && t.semConvMetricRegistry.HTTPClientRequestDuration() != nil {
+		var attrs []attribute.KeyValue
+
+		if statusCode < 100 || statusCode >= 600 {
+			attrs = append(attrs, attribute.Key("error.type").String(fmt.Sprintf("Invalid HTTP status code %d", statusCode)))
+		} else if statusCode >= 400 {
+			attrs = append(attrs, attribute.Key("error.type").String(strconv.Itoa(statusCode)))
+		}
+
+		attrs = append(attrs, semconv.HTTPRequestMethodKey.String(req.Method))
+		attrs = append(attrs, semconv.HTTPResponseStatusCode(statusCode))
+		attrs = append(attrs, semconv.NetworkProtocolName(strings.ToLower(req.Proto)))
+		attrs = append(attrs, semconv.NetworkProtocolVersion(observability.Proto(req.Proto)))
+		attrs = append(attrs, semconv.ServerAddress(req.URL.Host))
+
+		_, port, err := net.SplitHostPort(req.URL.Host)
+		if err != nil {
+			switch req.URL.Scheme {
+			case "http":
+				attrs = append(attrs, semconv.ServerPort(80))
+			case "https":
+				attrs = append(attrs, semconv.ServerPort(443))
+			}
+		} else {
+			intPort, _ := strconv.Atoi(port)
+			attrs = append(attrs, semconv.ServerPort(intPort))
+		}
+
+		attrs = append(attrs, semconv.URLScheme(req.Header.Get("X-Forwarded-Proto")))
+
+		t.semConvMetricRegistry.HTTPClientRequestDuration().Record(req.Context(), end.Sub(start).Seconds(), metric.WithAttributes(attrs...))
+	}
+
+	return response, err
+}