add option to skip clearing the route cache in grpc transcoder filter

Signed-off-by: ilackarms <sdw35@cornell.edu>

bazel/repository_locations.bzl

@@ -76,7 +76,7 @@ REPOSITORY_LOCATIONS = dict(
         urls = ["https://github.com/google/protobuf/archive/v3.5.0.tar.gz"],
     ),
     envoy_api = dict(
-        commit = "e73b8264a26c909f75d38ec2c73d9f47ad1b3b57",
+        commit = "c4590ec24e33a1205bde3ba13ea025664c4f3bb4",
         remote = "https://github.com/envoyproxy/data-plane-api",
     ),
     grpc_httpjson_transcoding = dict(

source/common/grpc/json_transcoder_filter.cc

@@ -127,8 +127,12 @@ JsonTranscoderConfig::JsonTranscoderConfig(
   print_options_.always_print_primitive_fields = print_config.always_print_primitive_fields();
   print_options_.always_print_enums_as_ints = print_config.always_print_enums_as_ints();
   print_options_.preserve_proto_field_names = print_config.preserve_proto_field_names();
+
+  match_incoming_request_route_ = proto_config.match_incoming_request_route();
 }
 
+bool JsonTranscoderConfig::matchIncomingRequestRoute() { return match_incoming_request_route_; }
+
 ProtobufUtil::Status JsonTranscoderConfig::createTranscoder(
     const Http::HeaderMap& headers, ZeroCopyInputStream& request_input,
     google::grpc::transcoding::TranscoderInputStream& response_input,
@@ -217,7 +221,9 @@ Http::FilterHeadersStatus JsonTranscoderFilter::decodeHeaders(Http::HeaderMap& h
   headers.insertMethod().value().setReference(Http::Headers::get().MethodValues.Post);
   headers.insertTE().value().setReference(Http::Headers::get().TEValues.Trailers);
 
-  decoder_callbacks_->clearRouteCache();
+  if (!config_.matchIncomingRequestRoute()) {
+    decoder_callbacks_->clearRouteCache();
+  }
 
   if (end_stream) {
     request_in_.finish();

source/common/grpc/json_transcoder_filter.h

@@ -62,6 +62,13 @@ class JsonTranscoderConfig : public Logger::Loggable<Logger::Id::config> {
                    std::unique_ptr<google::grpc::transcoding::Transcoder>& transcoder,
                    const Protobuf::MethodDescriptor*& method_descriptor);
 
+  /**
+   * If true, skip clearing the route cache after the incoming request has been modified.
+   * This allows Envoy to select the upstream cluster based on the incoming request
+   * rather than the outgoing.
+   */
+  bool matchIncomingRequestRoute();
+
 private:
   /**
    * Convert method descriptor to RequestInfo that needed for transcoding library
@@ -74,6 +81,8 @@ class JsonTranscoderConfig : public Logger::Loggable<Logger::Id::config> {
   google::grpc::transcoding::PathMatcherPtr<const Protobuf::MethodDescriptor*> path_matcher_;
   std::unique_ptr<google::grpc::transcoding::TypeHelper> type_helper_;
   Protobuf::util::JsonPrintOptions print_options_;
+
+  bool match_incoming_request_route_{false};
 };
 
 typedef std::shared_ptr<JsonTranscoderConfig> JsonTranscoderConfigSharedPtr;

test/common/grpc/json_transcoder_filter_test.cc

@@ -43,12 +43,14 @@ namespace Grpc {
 class GrpcJsonTranscoderConfigTest : public testing::Test {
 public:
   const envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder
-  getProtoConfig(const std::string& descriptor_path, const std::string& service_name) {
+  getProtoConfig(const std::string& descriptor_path, const std::string& service_name,
+                 const bool skip_recalculating_route = false) {
     std::string json_string = "{\"proto_descriptor\": \"" + descriptor_path +
                               "\",\"services\": [\"" + service_name + "\"]}";
     auto json_config = Json::Factory::loadFromString(json_string);
     envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder proto_config;
     Envoy::Config::FilterJson::translateGrpcJsonTranscoder(*json_config, proto_config);
+    proto_config.set_skip_recalculating_route(skip_recalculating_route);
     return proto_config;
   }
 
@@ -105,6 +107,12 @@ TEST_F(GrpcJsonTranscoderConfigTest, ParseConfig) {
       TestEnvironment::runfilesPath("test/proto/bookstore.descriptor"), "bookstore.Bookstore")));
 }
 
+TEST_F(GrpcJsonTranscoderConfigTest, ParseConfigSkipRecalculating) {
+  EXPECT_NO_THROW(JsonTranscoderConfig config(
+      getProtoConfig(TestEnvironment::runfilesPath("test/proto/bookstore.descriptor"),
+                     "bookstore.Bookstore", true)));
+}
+
 TEST_F(GrpcJsonTranscoderConfigTest, ParseBinaryConfig) {
   envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder proto_config;
   proto_config.set_proto_descriptor_bin(
@@ -197,17 +205,20 @@ TEST_F(GrpcJsonTranscoderConfigTest, InvalidVariableBinding) {
 
 class GrpcJsonTranscoderFilterTest : public testing::Test {
 public:
-  GrpcJsonTranscoderFilterTest() : config_(bookstoreProtoConfig()), filter_(config_) {
+  GrpcJsonTranscoderFilterTest(const bool skip_recalculating_route = false)
+      : config_(bookstoreProtoConfig(skip_recalculating_route)), filter_(config_) {
     filter_.setDecoderFilterCallbacks(decoder_callbacks_);
     filter_.setEncoderFilterCallbacks(encoder_callbacks_);
   }
 
-  const envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder bookstoreProtoConfig() {
+  const envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder
+  bookstoreProtoConfig(const bool skip_recalculating_route) {
     std::string json_string = "{\"proto_descriptor\": \"" + bookstoreDescriptorPath() +
                               "\",\"services\": [\"bookstore.Bookstore\"]}";
     auto json_config = Json::Factory::loadFromString(json_string);
     envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder proto_config{};
     Envoy::Config::FilterJson::translateGrpcJsonTranscoder(*json_config, proto_config);
+    proto_config.set_skip_recalculating_route(skip_recalculating_route);
     return proto_config;
   }
 
@@ -222,6 +233,11 @@ class GrpcJsonTranscoderFilterTest : public testing::Test {
   NiceMock<Http::MockStreamEncoderFilterCallbacks> encoder_callbacks_;
 };
 
+class GrpcJsonTranscoderFilterSkipRecalculatingTest : public GrpcJsonTranscoderFilterTest {
+public:
+  GrpcJsonTranscoderFilterSkipRecalculatingTest() : GrpcJsonTranscoderFilterTest(true) {}
+};
+
 TEST_F(GrpcJsonTranscoderFilterTest, NoTranscoding) {
   Http::TestHeaderMapImpl request_headers{{"content-type", "application/grpc"},
                                           {":method", "POST"},
@@ -324,6 +340,24 @@ TEST_F(GrpcJsonTranscoderFilterTest, TranscodingUnaryPost) {
   EXPECT_EQ(Http::FilterTrailersStatus::Continue, filter_.decodeTrailers(response_trailers));
 }
 
+TEST_F(GrpcJsonTranscoderFilterSkipRecalculatingTest, TranscodingUnaryPostSkipRecalculate) {
+  Http::TestHeaderMapImpl request_headers{
+      {"content-type", "application/json"}, {":method", "POST"}, {":path", "/shelf"}};
+
+  EXPECT_CALL(decoder_callbacks_, clearRouteCache()).Times(0);
+
+  EXPECT_EQ(Http::FilterHeadersStatus::Continue, filter_.decodeHeaders(request_headers, false));
+
+  EXPECT_EQ("application/grpc", request_headers.get_("content-type"));
+  EXPECT_EQ("/shelf", request_headers.get_("x-envoy-original-path"));
+  EXPECT_EQ("/bookstore.Bookstore/CreateShelf", request_headers.get_(":path"));
+  EXPECT_EQ("trailers", request_headers.get_("te"));
+
+  Buffer::OwnedImpl request_data{"{\"theme\": \"Children\"}"};
+
+  EXPECT_EQ(Http::FilterDataStatus::Continue, filter_.decodeData(request_data, true));
+}
+
 TEST_F(GrpcJsonTranscoderFilterTest, TranscodingUnaryError) {
   Http::TestHeaderMapImpl request_headers{
       {"content-type", "application/json"}, {":method", "POST"}, {":path", "/shelf"}};