feat: Add ability to echo request headers in trailing metadata

cmd/gapic-showcase/echo.go

@@ -59,6 +59,8 @@ func init() {
 
 	EchoCmd.Flags().StringVar(&echoInputOtherRequestId, "other_request_id", "", "To facilitate testing of...")
 
+	EchoCmd.Flags().StringSliceVar(&EchoInput.HttpRequestHeaderToEcho, "http_request_header_to_echo", []string{}, "Http request headers to echo via...")
+
 	EchoCmd.Flags().StringVar(&EchoInputResponse, "response", "", "Choices: content, error")
 
 	EchoCmd.Flags().StringVar(&EchoFromFile, "from_file", "", "Absolute path to JSON file containing request payload")

schema/google/showcase/v1beta1/echo.proto

@@ -222,6 +222,9 @@ message EchoRequest {
   optional string other_request_id = 8 [
     (google.api.field_info).format = UUID4
   ];
+
+  // Http request headers to echo via EchoResponse.http_request_header_value
+  repeated string http_request_header_to_echo = 9;
 }
 
 // The response message for the Echo methods.
@@ -237,6 +240,13 @@ message EchoResponse {
 
   // The other request ID specified or autopopulated in the request.
   string other_request_id = 4;
+
+
+  message RepeatedValues {
+    repeated string header_values = 1;
+  }
+  // The HTTP header to echo as specified in the request
+  map<string, RepeatedValues> http_request_header_value = 5;
 }
 
 // The request message used for the EchoErrorDetails method.

server/services/echo_service.go

@@ -46,12 +46,21 @@ type echoServerImpl struct {
 
 func (s *echoServerImpl) Echo(ctx context.Context, in *pb.EchoRequest) (*pb.EchoResponse, error) {
 	err := status.ErrorProto(in.GetError())
-	if err != nil {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if err != nil || !ok {
 		return nil, err
 	}
 	echoHeaders(ctx)
 	echoTrailers(ctx)
-	return &pb.EchoResponse{Content: in.GetContent(), Severity: in.GetSeverity(), RequestId: in.GetRequestId(), OtherRequestId: in.GetOtherRequestId()}, nil
+	requestHeaders := make(map[string]*pb.EchoResponse_RepeatedValues)
+	headersToTrack := in.GetHttpRequestHeaderToEcho()
+	for k, v := range md {
+		if strContains(headersToTrack, k) {
+			requestHeaders[k] = &pb.EchoResponse_RepeatedValues{HeaderValues: v}
+		}
+	}
+
+	return &pb.EchoResponse{Content: in.GetContent(), Severity: in.GetSeverity(), RequestId: in.GetRequestId(), OtherRequestId: in.GetOtherRequestId(), HttpRequestHeaderValue: requestHeaders}, nil
 }
 
 func (s *echoServerImpl) EchoErrorDetails(ctx context.Context, in *pb.EchoErrorDetailsRequest) (*pb.EchoErrorDetailsResponse, error) {
@@ -141,6 +150,8 @@ func (s *echoServerImpl) Chat(stream pb.Echo_ChatServer) error {
 	for {
 		req, err := stream.Recv()
 		if err == io.EOF {
+			// Echo headers and trailers when the stream ends
+			echoStreamingHeaders(stream)
 			echoStreamingTrailers(stream)
 			return nil
 		}
@@ -152,7 +163,6 @@ func (s *echoServerImpl) Chat(stream pb.Echo_ChatServer) error {
 		if s != nil {
 			return s
 		}
-		echoStreamingHeaders(stream)
 		stream.Send(&pb.EchoResponse{Content: req.GetContent()})
 	}
 }

server/services/echo_service_test.go

@@ -42,12 +42,16 @@ func TestEcho_success(t *testing.T) {
 	server := NewEchoServer()
 	for _, val := range table {
 		in := &pb.EchoRequest{
-			Response: &pb.EchoRequest_Content{Content: val},
-			Severity: pb.Severity_CRITICAL,
+			Response:                &pb.EchoRequest_Content{Content: val},
+			Severity:                pb.Severity_CRITICAL,
+			HttpRequestHeaderToEcho: []string{"x-goog-api-version"},
 		}
 		mockStream := &mockUnaryStream{t: t}
 		ctx := appendTestOutgoingMetadata(context.Background(), &mockSTS{t: t, stream: mockStream})
 		out, err := server.Echo(ctx, in)
+		if !reflect.DeepEqual(out.HttpRequestHeaderValue["x-goog-api-version"].HeaderValues[0], "apiVersion") {
+			t.Errorf("Did not find apiVersion in response")
+		}
 		if err != nil {
 			t.Error(err)
 		}
@@ -153,6 +157,7 @@ func (m *mockExpandStream) SetTrailer(md metadata.MD) {
 
 func (m *mockExpandStream) SetHeader(md metadata.MD) error {
 	m.head = append(m.head, md.Get("x-goog-request-params")...)
+	m.head = append(m.head, md.Get("x-goog-api-version")...)
 	return nil
 }
 
@@ -367,7 +372,7 @@ func (m *mockChatStream) SetTrailer(md metadata.MD) {
 }
 
 func (m *mockChatStream) verify(expectHeadersAndTrailers bool) {
-	if expectHeadersAndTrailers && !reflect.DeepEqual([]string{"show", "case"}, m.trail) && !reflect.DeepEqual([]string{"showcaseHeader", "anotherHeader"}, m.head) {
+	if expectHeadersAndTrailers && (!reflect.DeepEqual([]string{"show", "case"}, m.trail) || !reflect.DeepEqual([]string{"showcaseHeader", "anotherHeader"}, m.head)) {
 		m.t.Errorf("Chat did not get all expected trailers.\nGot these headers: %+v\nGot these trailers: %+v", m.head, m.trail)
 	}
 }
@@ -898,6 +903,6 @@ func TestBlockError(t *testing.T) {
 
 func appendTestOutgoingMetadata(ctx context.Context, stream grpc.ServerTransportStream) context.Context {
 	ctx = grpc.NewContextWithServerTransportStream(ctx, stream)
-	ctx = metadata.NewIncomingContext(ctx, metadata.Pairs("showcase-trailer", "show", "showcase-trailer", "case", "trailer", "trail", "x-goog-request-params", "showcaseHeader", "x-goog-request-params", "anotherHeader", "header", "head"))
+	ctx = metadata.NewIncomingContext(ctx, metadata.Pairs("showcase-trailer", "show", "showcase-trailer", "case", "trailer", "trail", "x-goog-request-params", "showcaseHeader", "x-goog-request-params", "anotherHeader", "header", "head", "x-goog-api-version", "apiVersion"))
 	return ctx
 }