adds Set-Cookie method to the HTTP transport. (#3353)

transport/http/server.go

@@ -296,6 +296,7 @@ func (s *Server) filter() mux.MiddlewareFunc {
 				reqHeader:    headerCarrier(req.Header),
 				replyHeader:  headerCarrier(w.Header()),
 				request:      req,
+				response:     w,
 			}
 			if s.endpoint != nil {
 				tr.endpoint = s.endpoint.String()

transport/http/transport.go

@@ -23,6 +23,7 @@ type Transport struct {
 	reqHeader    headerCarrier
 	replyHeader  headerCarrier
 	request      *http.Request
+	response     http.ResponseWriter
 	pathTemplate string
 }
 
@@ -70,6 +71,17 @@ func SetOperation(ctx context.Context, op string) {
 	}
 }
 
+// SetCookie adds a Set-Cookie header to the provided [ResponseWriter]'s headers.
+// The provided cookie must have a valid Name. Invalid cookies may be
+// silently dropped.
+func SetCookie(ctx context.Context, cookie *http.Cookie) {
+	if tr, ok := transport.FromServerContext(ctx); ok {
+		if tr, ok := tr.(*Transport); ok {
+			http.SetCookie(tr.response, cookie)
+		}
+	}
+}
+
 // RequestFromServerContext returns request from context.
 func RequestFromServerContext(ctx context.Context) (*http.Request, bool) {
 	if tr, ok := transport.FromServerContext(ctx); ok {