Add captured headers options for tracing

Co-authored-by: Baptiste Mayelle <baptiste.mayelle@traefik.io>

pkg/server/middleware/observability.go

@@ -15,7 +15,7 @@ import (
 	"github.com/traefik/traefik/v3/pkg/middlewares/capture"
 	metricsMiddle "github.com/traefik/traefik/v3/pkg/middlewares/metrics"
 	tracingMiddle "github.com/traefik/traefik/v3/pkg/middlewares/tracing"
-	"go.opentelemetry.io/otel/trace"
+	"github.com/traefik/traefik/v3/pkg/tracing"
 )
 
 // ObservabilityMgr is a manager for observability (AccessLogs, Metrics and Tracing) enablement.
@@ -23,12 +23,12 @@ type ObservabilityMgr struct {
 	config                 static.Configuration
 	accessLoggerMiddleware *accesslog.Handler
 	metricsRegistry        metrics.Registry
-	tracer                 trace.Tracer
+	tracer                 *tracing.Tracer
 	tracerCloser           io.Closer
 }
 
 // NewObservabilityMgr creates a new ObservabilityMgr.
-func NewObservabilityMgr(config static.Configuration, metricsRegistry metrics.Registry, accessLoggerMiddleware *accesslog.Handler, tracer trace.Tracer, tracerCloser io.Closer) *ObservabilityMgr {
+func NewObservabilityMgr(config static.Configuration, metricsRegistry metrics.Registry, accessLoggerMiddleware *accesslog.Handler, tracer *tracing.Tracer, tracerCloser io.Closer) *ObservabilityMgr {
 	return &ObservabilityMgr{
 		config:                 config,
 		metricsRegistry:        metricsRegistry,

pkg/server/service/tracing_roundtripper.go

@@ -14,25 +14,27 @@ type wrapper struct {
 
 func (t *wrapper) RoundTrip(req *http.Request) (*http.Response, error) {
 	var span trace.Span
-	if tracer := tracing.TracerFromContext(req.Context()); tracer != nil {
+	var tracer *tracing.Tracer
+	if tracer = tracing.TracerFromContext(req.Context()); tracer != nil {
 		var tracingCtx context.Context
 		tracingCtx, span = tracer.Start(req.Context(), "ReverseProxy", trace.WithSpanKind(trace.SpanKindClient))
 		defer span.End()
 
 		req = req.WithContext(tracingCtx)
 
-		tracing.LogClientRequest(span, req)
+		tracer.CaptureClientRequest(span, req)
 		tracing.InjectContextIntoCarrier(req)
 	}
 
 	response, err := t.rt.RoundTrip(req)
 	if err != nil {
 		statusCode := computeStatusCode(err)
-		tracing.LogResponseCode(span, statusCode, trace.SpanKindClient)
+		tracer.CaptureResponse(span, nil, statusCode, trace.SpanKindClient)
+
 		return response, err
 	}
 
-	tracing.LogResponseCode(span, response.StatusCode, trace.SpanKindClient)
+	tracer.CaptureResponse(span, response.Header, response.StatusCode, trace.SpanKindClient)
 
 	return response, nil
 }

pkg/server/service/tracing_roundtripper_test.go

@@ -0,0 +1,138 @@
+package service
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/traefik/traefik/v3/pkg/tracing"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
+	"go.opentelemetry.io/otel/trace/embedded"
+)
+
+func TestTracingRoundTripper(t *testing.T) {
+	type expected struct {
+		name       string
+		attributes []attribute.KeyValue
+	}
+
+	testCases := []struct {
+		desc     string
+		expected []expected
+	}{
+		{
+			desc: "basic test",
+			expected: []expected{
+				{
+					name: "initial",
+					attributes: []attribute.KeyValue{
+						attribute.String("span.kind", "unspecified"),
+					},
+				},
+				{
+					name: "ReverseProxy",
+					attributes: []attribute.KeyValue{
+						attribute.String("span.kind", "client"),
+						attribute.String("http.request.method", "GET"),
+						attribute.String("network.protocol.version", "1.1"),
+						attribute.String("url.full", "http://www.test.com/search?q=Opentelemetry"),
+						attribute.String("url.scheme", "http"),
+						attribute.String("user_agent.original", "reverse-test"),
+						attribute.String("network.peer.address", ""),
+						attribute.String("server.address", "www.test.com"),
+						attribute.String("network.peer.port", "80"),
+						attribute.Int64("server.port", int64(80)),
+						attribute.StringSlice("http.request.header.x-foo", []string{"foo", "bar"}),
+						attribute.Int64("http.response.status_code", int64(404)),
+						attribute.StringSlice("http.response.header.x-bar", []string{"foo", "bar"}),
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, "http://www.test.com/search?q=Opentelemetry", nil)
+			req.RemoteAddr = "10.0.0.1:1234"
+			req.Header.Set("User-Agent", "reverse-test")
+			req.Header.Set("X-Forwarded-Proto", "http")
+			req.Header.Set("X-Foo", "foo")
+			req.Header.Add("X-Foo", "bar")
+
+			mockTracer := &mockTracer{}
+			tracer := tracing.NewTracer(mockTracer, []string{"X-Foo"}, []string{"X-Bar"})
+			initialCtx, initialSpan := tracer.Start(req.Context(), "initial")
+			defer initialSpan.End()
+			req = req.WithContext(initialCtx)
+
+			tracingRoundTripper := newTracingRoundTripper(roundTripperFn(func(req *http.Request) (*http.Response, error) {
+				return &http.Response{
+					Header: map[string][]string{
+						"X-Bar": {"foo", "bar"},
+					},
+					StatusCode: http.StatusNotFound,
+				}, nil
+			}))
+
+			_, err := tracingRoundTripper.RoundTrip(req)
+			require.NoError(t, err)
+
+			for i, span := range mockTracer.spans {
+				assert.Equal(t, test.expected[i].name, span.name)
+				assert.Equal(t, test.expected[i].attributes, span.attributes)
+			}
+		})
+	}
+}
+
+type mockTracer struct {
+	embedded.Tracer
+
+	spans []*mockSpan
+}
+
+var _ trace.Tracer = &mockTracer{}
+
+func (t *mockTracer) Start(ctx context.Context, name string, opts ...trace.SpanStartOption) (context.Context, trace.Span) {
+	config := trace.NewSpanStartConfig(opts...)
+	span := &mockSpan{}
+	span.SetName(name)
+	span.SetAttributes(attribute.String("span.kind", config.SpanKind().String()))
+	span.SetAttributes(config.Attributes()...)
+	t.spans = append(t.spans, span)
+	return trace.ContextWithSpan(ctx, span), span
+}
+
+// mockSpan is an implementation of Span that preforms no operations.
+type mockSpan struct {
+	embedded.Span
+
+	name       string
+	attributes []attribute.KeyValue
+}
+
+var _ trace.Span = &mockSpan{}
+
+func (*mockSpan) SpanContext() trace.SpanContext {
+	return trace.NewSpanContext(trace.SpanContextConfig{TraceID: trace.TraceID{1}, SpanID: trace.SpanID{1}})
+}
+func (*mockSpan) IsRecording() bool                  { return false }
+func (s *mockSpan) SetStatus(_ codes.Code, _ string) {}
+func (s *mockSpan) SetAttributes(kv ...attribute.KeyValue) {
+	s.attributes = append(s.attributes, kv...)
+}
+func (s *mockSpan) End(...trace.SpanEndOption)                  {}
+func (s *mockSpan) RecordError(_ error, _ ...trace.EventOption) {}
+func (s *mockSpan) AddEvent(_ string, _ ...trace.EventOption)   {}
+
+func (s *mockSpan) SetName(name string) { s.name = name }
+
+func (s *mockSpan) TracerProvider() trace.TracerProvider {
+	return nil
+}