feat(golang): implement DD_TRACE_PROPAGATION_BEHAVIOR_EXTRACT (#6757)

Co-authored-by: genesor <benjamin.debernardi@datadoghq.com>

Author: igoragoli

manifests/golang.yml

@@ -1428,11 +1428,11 @@ manifest:
       component_version: <=1.41.0
   tests/test_identify.py::Test_Propagate: v1.48.0-rc.1
   tests/test_identify.py::Test_Propagate_Legacy: v1.41.0
-  tests/test_library_conf.py::Test_ExtractBehavior_Default: missing_feature (baggage should be implemented and conflicting trace contexts should generate span link in v1.71.0)
-  tests/test_library_conf.py::Test_ExtractBehavior_Ignore: missing_feature (extract behavior not implemented)
-  tests/test_library_conf.py::Test_ExtractBehavior_Restart: missing_feature (extract behavior not implemented)
+  tests/test_library_conf.py::Test_ExtractBehavior_Default: v2.10.0-dev
+  tests/test_library_conf.py::Test_ExtractBehavior_Ignore: v2.10.0-dev
+  tests/test_library_conf.py::Test_ExtractBehavior_Restart: v2.10.0-dev
   tests/test_library_conf.py::Test_ExtractBehavior_Restart_Otel: missing_feature (OTel extraction endpoint not implemented)
-  tests/test_library_conf.py::Test_ExtractBehavior_Restart_With_Extract_First: missing_feature (extract behavior not implemented)
+  tests/test_library_conf.py::Test_ExtractBehavior_Restart_With_Extract_First: v2.10.0-dev
   tests/test_library_conf.py::Test_HeaderTags: v1.53.0
   tests/test_library_conf.py::Test_HeaderTags_Colon_Leading: v1.53.0
   tests/test_library_conf.py::Test_HeaderTags_Colon_Trailing: v1.70.0

utils/build/docker/golang/app/chi/main.go

@@ -159,6 +159,11 @@ func main() {
 
 		client := httptrace.WrapClient(http.DefaultClient)
 		req, _ := http.NewRequestWithContext(r.Context(), http.MethodGet, url, nil)
+		// Inject the current span's context into req.Header so headers are
+		// visible after client.Do (the wrapped client injects into a cloned request).
+		if span, ok := tracer.SpanFromContext(r.Context()); ok {
+			tracer.Inject(span.Context(), tracer.HTTPHeadersCarrier(req.Header))
+		}
 		res, err := client.Do(req)
 		if err != nil {
 			logrus.Fatalln("client.Do", err)
@@ -168,7 +173,7 @@ func main() {
 
 		requestHeaders := make(map[string]string, len(req.Header))
 		for key, values := range req.Header {
-			requestHeaders[key] = strings.Join(values, ",")
+			requestHeaders[strings.ToLower(key)] = strings.Join(values, ",")
 		}
 
 		responseHeaders := make(map[string]string, len(res.Header))

utils/build/docker/golang/app/echo/main.go

@@ -174,6 +174,11 @@ func main() {
 
 		client := httptrace.WrapClient(http.DefaultClient)
 		req, _ := http.NewRequestWithContext(c.Request().Context(), http.MethodGet, url, nil)
+		// Inject the current span's context into req.Header so headers are
+		// visible after client.Do (the wrapped client injects into a cloned request).
+		if span, ok := tracer.SpanFromContext(c.Request().Context()); ok {
+			tracer.Inject(span.Context(), tracer.HTTPHeadersCarrier(req.Header))
+		}
 		res, err := client.Do(req)
 		if err != nil {
 			logrus.Fatalln(err)
@@ -183,7 +188,7 @@ func main() {
 
 		requestHeaders := make(map[string]string, len(req.Header))
 		for key, values := range req.Header {
-			requestHeaders[key] = strings.Join(values, ",")
+			requestHeaders[strings.ToLower(key)] = strings.Join(values, ",")
 		}
 
 		responseHeaders := make(map[string]string, len(res.Header))

utils/build/docker/golang/app/gin/main.go

@@ -165,6 +165,11 @@ func main() {
 
 		client := httptrace.WrapClient(http.DefaultClient)
 		req, _ := http.NewRequestWithContext(ctx.Request.Context(), http.MethodGet, url, nil)
+		// Inject the current span's context into req.Header so headers are
+		// visible after client.Do (the wrapped client injects into a cloned request).
+		if span, ok := tracer.SpanFromContext(ctx.Request.Context()); ok {
+			tracer.Inject(span.Context(), tracer.HTTPHeadersCarrier(req.Header))
+		}
 		res, err := client.Do(req)
 		if err != nil {
 			logrus.Fatalln(err)
@@ -174,7 +179,7 @@ func main() {
 
 		requestHeaders := make(map[string]string, len(req.Header))
 		for key, values := range req.Header {
-			requestHeaders[key] = strings.Join(values, ",")
+			requestHeaders[strings.ToLower(key)] = strings.Join(values, ",")
 		}
 
 		responseHeaders := make(map[string]string, len(res.Header))

utils/build/docker/golang/app/net-http-orchestrion/main.go

@@ -152,6 +152,11 @@ func main() {
 		}
 
 		req, _ := http.NewRequestWithContext(r.Context(), http.MethodGet, url, nil)
+		// Inject the current span's context into req.Header so headers are
+		// visible after Do (the instrumented client injects into a cloned request).
+		if span, ok := tracer.SpanFromContext(r.Context()); ok {
+			tracer.Inject(span.Context(), tracer.HTTPHeadersCarrier(req.Header))
+		}
 		res, err := http.DefaultClient.Do(req)
 		if err != nil {
 			log.Fatalln("client.Do", err)
@@ -161,7 +166,7 @@ func main() {
 
 		requestHeaders := make(map[string]string, len(req.Header))
 		for key, values := range req.Header {
-			requestHeaders[key] = strings.Join(values, ",")
+			requestHeaders[strings.ToLower(key)] = strings.Join(values, ",")
 		}
 
 		responseHeaders := make(map[string]string, len(res.Header))

utils/build/docker/golang/app/net-http/main.go

@@ -197,6 +197,11 @@ func main() {
 
 		client := httptrace.WrapClient(http.DefaultClient)
 		req, _ := http.NewRequestWithContext(r.Context(), http.MethodGet, url, nil)
+		// Inject the current span's context into req.Header so headers are
+		// visible after client.Do (the wrapped client injects into a cloned request).
+		if span, ok := tracer.SpanFromContext(r.Context()); ok {
+			tracer.Inject(span.Context(), tracer.HTTPHeadersCarrier(req.Header))
+		}
 		res, err := client.Do(req)
 		if err != nil {
 			logrus.Fatalln("client.Do", err)
@@ -206,7 +211,7 @@ func main() {
 
 		requestHeaders := make(map[string]string, len(req.Header))
 		for key, values := range req.Header {
-			requestHeaders[key] = strings.Join(values, ",")
+			requestHeaders[strings.ToLower(key)] = strings.Join(values, ",")
 		}
 
 		responseHeaders := make(map[string]string, len(res.Header))