Collect and send extra HTTP headers to the agent

instrumentation_http.go

@@ -63,15 +63,34 @@ func TracingHandlerFunc(sensor *Sensor, pathTemplate string, handler http.Handle
 		span := tracer.StartSpan("g.http", opts...)
 		defer span.Finish()
 
+		var collectableHTTPHeaders []string
 		if t, ok := tracer.(Tracer); ok {
-			params := collectHTTPParams(req, t.Options().Secrets)
+			opts := t.Options()
+			collectableHTTPHeaders = opts.CollectableHTTPHeaders
+
+			params := collectHTTPParams(req, opts.Secrets)
 			if len(params) > 0 {
 				span.SetTag("http.params", params.Encode())
 			}
 		}
 
+		collectedHeaders := make(map[string]string)
+		// make sure collected headers are sent in case of panic/error
 		defer func() {
-			// Be sure to capture any kind of panic / error
+			if len(collectedHeaders) > 0 {
+				span.SetTag("http.header", collectedHeaders)
+			}
+		}()
+
+		// collect request headers
+		for _, h := range collectableHTTPHeaders {
+			if v := req.Header.Get(h); v != "" {
+				collectedHeaders[h] = v
+			}
+		}
+
+		defer func() {
+			// Be sure to capture any kind of panic/error
 			if err := recover(); err != nil {
 				if e, ok := err.(error); ok {
 					span.SetTag("http.error", e.Error())
@@ -94,6 +113,13 @@ func TracingHandlerFunc(sensor *Sensor, pathTemplate string, handler http.Handle
 		ctx = ContextWithSpan(ctx, span)
 		w3ctrace.TracingHandlerFunc(handler)(wrapped, req.WithContext(ctx))
 
+		// collect response headers
+		for _, h := range collectableHTTPHeaders {
+			if v := wrapped.Header().Get(h); v != "" {
+				collectedHeaders[h] = v
+			}
+		}
+
 		if wrapped.Status > 0 {
 			if wrapped.Status > http.StatusInternalServerError {
 				span.SetTag("http.error", http.StatusText(wrapped.Status))
@@ -136,20 +162,46 @@ func RoundTripper(sensor *Sensor, original http.RoundTripper) http.RoundTripper
 		req = cloneRequest(ContextWithSpan(ctx, span), req)
 		sensor.Tracer().Inject(span.Context(), ot.HTTPHeaders, ot.HTTPHeadersCarrier(req.Header))
 
+		var collectableHTTPHeaders []string
 		if t, ok := sensor.Tracer().(Tracer); ok {
-			params := collectHTTPParams(req, t.Options().Secrets)
+			opts := t.Options()
+			collectableHTTPHeaders = opts.CollectableHTTPHeaders
+
+			params := collectHTTPParams(req, opts.Secrets)
 			if len(params) > 0 {
 				span.SetTag("http.params", params.Encode())
 			}
 		}
 
+		collectedHeaders := make(map[string]string)
+		// make sure collected headers are sent in case of panic/error
+		defer func() {
+			if len(collectedHeaders) > 0 {
+				span.SetTag("http.header", collectedHeaders)
+			}
+		}()
+
+		// collect request headers
+		for _, h := range collectableHTTPHeaders {
+			if v := req.Header.Get(h); v != "" {
+				collectedHeaders[h] = v
+			}
+		}
+
 		resp, err := original.RoundTrip(req)
 		if err != nil {
 			span.SetTag("http.error", err.Error())
 			span.LogFields(otlog.Error(err))
 			return resp, err
 		}
 
+		// collect response headers
+		for _, h := range collectableHTTPHeaders {
+			if v := resp.Header.Get(h); v != "" {
+				collectedHeaders[h] = v
+			}
+		}
+
 		span.SetTag(string(ext.HTTPStatusCode), resp.StatusCode)
 
 		return resp, err

instrumentation_http_test.go

@@ -21,10 +21,14 @@ func TestTracingHandlerFunc_Write(t *testing.T) {
 	}, recorder))
 
 	h := instana.TracingHandlerFunc(s, "/{action}", func(w http.ResponseWriter, req *http.Request) {
+		w.Header().Set("X-Response", "true")
+		w.Header().Set("X-Custom-Header-2", "response")
 		fmt.Fprintln(w, "Ok")
 	})
 
 	req := httptest.NewRequest(http.MethodGet, "/test?q=term", nil)
+	req.Header.Set("Authorization", "Basic blah")
+	req.Header.Set("X-Custom-Header-1", "request")
 
 	rec := httptest.NewRecorder()
 	h.ServeHTTP(rec, req)
@@ -48,11 +52,15 @@ func TestTracingHandlerFunc_Write(t *testing.T) {
 	data := span.Data.(instana.HTTPSpanData)
 
 	assert.Equal(t, instana.HTTPSpanTags{
-		Host:         "example.com",
-		Status:       http.StatusOK,
-		Method:       "GET",
-		Path:         "/test",
-		Params:       "q=term",
+		Host:   "example.com",
+		Status: http.StatusOK,
+		Method: "GET",
+		Path:   "/test",
+		Params: "q=term",
+		Headers: map[string]string{
+			"x-custom-header-1": "request",
+			"x-custom-header-2": "response",
+		},
 		PathTemplate: "/{action}",
 	}, data.Tags)
 
@@ -337,11 +345,17 @@ func TestRoundTripper(t *testing.T) {
 		return &http.Response{
 			Status:     http.StatusText(http.StatusNotImplemented),
 			StatusCode: http.StatusNotImplemented,
+			Header: http.Header{
+				"X-Response":        []string{"true"},
+				"X-Custom-Header-2": []string{"response"},
+			},
 		}, nil
 	}))
 
 	ctx := instana.ContextWithSpan(context.Background(), parentSpan)
 	req := httptest.NewRequest("GET", "http://user:[email protected]/hello?q=term&sensitive_key=s3cr3t&myPassword=qwerty&SECRET_VALUE=1", nil)
+	req.Header.Set("X-Custom-Header-1", "request")
+	req.Header.Set("Authorization", "Basic blah")
 
 	_, err := rt.RoundTrip(req.WithContext(ctx))
 	require.NoError(t, err)
@@ -369,6 +383,10 @@ func TestRoundTripper(t *testing.T) {
 		Status: http.StatusNotImplemented,
 		URL:    "http://example.com/hello",
 		Params: "SECRET_VALUE=%3Credacted%3E&myPassword=%3Credacted%3E&q=term&sensitive_key=%3Credacted%3E",
+		Headers: map[string]string{
+			"x-custom-header-1": "request",
+			"x-custom-header-2": "response",
+		},
 	}, data.Tags)
 }
 

sensor_test.go

@@ -12,6 +12,9 @@ const TestServiceName = "test_service"
 func TestMain(m *testing.M) {
 	instana.InitSensor(&instana.Options{
 		Service: TestServiceName,
+		Tracer: instana.TracerOptions{
+			CollectableHTTPHeaders: []string{"x-custom-header-1", "x-custom-header-2"},
+		},
 	})
 
 	os.Exit(m.Run())