Manage observability at entrypoint and router level

Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

pkg/middlewares/observability/semconv.go

@@ -0,0 +1,81 @@
+package observability
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/containous/alice"
+	"github.com/rs/zerolog/log"
+	"github.com/traefik/traefik/v3/pkg/logs"
+	"github.com/traefik/traefik/v3/pkg/metrics"
+	"github.com/traefik/traefik/v3/pkg/middlewares"
+	"github.com/traefik/traefik/v3/pkg/middlewares/capture"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
+)
+
+const (
+	semConvServerMetricsTypeName = "SemConvServerMetrics"
+)
+
+type semConvServerMetrics struct {
+	next                  http.Handler
+	semConvMetricRegistry *metrics.SemConvMetricsRegistry
+}
+
+// SemConvServerMetricsHandler return the alice.Constructor for semantic conventions servers metrics.
+func SemConvServerMetricsHandler(ctx context.Context, semConvMetricRegistry *metrics.SemConvMetricsRegistry) alice.Constructor {
+	return func(next http.Handler) (http.Handler, error) {
+		return newServerMetricsSemConv(ctx, semConvMetricRegistry, next), nil
+	}
+}
+
+// newServerMetricsSemConv creates a new semConv server metrics middleware for incoming requests.
+func newServerMetricsSemConv(ctx context.Context, semConvMetricRegistry *metrics.SemConvMetricsRegistry, next http.Handler) http.Handler {
+	middlewares.GetLogger(ctx, "tracing", semConvServerMetricsTypeName).Debug().Msg("Creating middleware")
+
+	return &semConvServerMetrics{
+		semConvMetricRegistry: semConvMetricRegistry,
+		next:                  next,
+	}
+}
+
+func (e *semConvServerMetrics) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	if e.semConvMetricRegistry == nil || e.semConvMetricRegistry.HTTPServerRequestDuration() == nil {
+		e.next.ServeHTTP(rw, req)
+		return
+	}
+
+	start := time.Now()
+	e.next.ServeHTTP(rw, req)
+	end := time.Now()
+
+	ctx := req.Context()
+	capt, err := capture.FromContext(ctx)
+	if err != nil {
+		log.Ctx(ctx).Error().Err(err).Str(logs.MiddlewareType, semConvServerMetricsTypeName).Msg("Could not get Capture")
+		return
+	}
+
+	var attrs []attribute.KeyValue
+
+	if capt.StatusCode() < 100 || capt.StatusCode() >= 600 {
+		attrs = append(attrs, attribute.Key("error.type").String(fmt.Sprintf("Invalid HTTP status code ; %d", capt.StatusCode())))
+	} else if capt.StatusCode() >= 400 {
+		attrs = append(attrs, attribute.Key("error.type").String(strconv.Itoa(capt.StatusCode())))
+	}
+
+	attrs = append(attrs, semconv.HTTPRequestMethodKey.String(req.Method))
+	attrs = append(attrs, semconv.HTTPResponseStatusCode(capt.StatusCode()))
+	attrs = append(attrs, semconv.NetworkProtocolName(strings.ToLower(req.Proto)))
+	attrs = append(attrs, semconv.NetworkProtocolVersion(Proto(req.Proto)))
+	attrs = append(attrs, semconv.ServerAddress(req.Host))
+	attrs = append(attrs, semconv.URLScheme(req.Header.Get("X-Forwarded-Proto")))
+
+	e.semConvMetricRegistry.HTTPServerRequestDuration().Record(req.Context(), end.Sub(start).Seconds(), metric.WithAttributes(attrs...))
+}