return trailer metadata in unary rpc

examples/integration_test.go

@@ -19,6 +19,7 @@ import (
 	sub "github.com/gengo/grpc-gateway/examples/sub"
 	"github.com/gengo/grpc-gateway/runtime"
 	"github.com/golang/protobuf/proto"
+	"google.golang.org/grpc/codes"
 )
 
 type aBitOfEverything struct {
@@ -44,11 +45,6 @@ func TestIntegration(t *testing.T) {
 			runtime.WithForwardResponseOption(
 				func(ctx context.Context, w http.ResponseWriter, _ proto.Message) error {
 					if md, ok := runtime.ServerMetadataFromContext(ctx); ok {
-						for k, vs := range md.HeaderMD {
-							for i := range vs {
-								w.Header().Add(fmt.Sprintf("Grpc-Header-%s", k), vs[i])
-							}
-						}
 						for k, vs := range md.TrailerMD {
 							for i := range vs {
 								w.Header().Add(fmt.Sprintf("Grpc-Trailer-%s", k), vs[i])
@@ -71,6 +67,7 @@ func TestIntegration(t *testing.T) {
 	testABECreateBody(t)
 	testABEBulkCreate(t)
 	testABELookup(t)
+	testABELookupNotFound(t)
 	testABEList(t)
 	testABEListError(t)
 	testAdditionalBindings(t)
@@ -161,11 +158,11 @@ func testEchoBody(t *testing.T) {
 		t.Errorf("msg.Id = %q; want %q", got, want)
 	}
 
-	if value := resp.Header.Get("Grpc-Header-foo"); value != "foo1" {
+	if value := resp.Header.Get("Grpc-Metadata-foo"); value != "foo1" {
 		t.Errorf("Grpc-Header-foo was %s, wanted %s", value, "foo1")
 	}
 
-	if value := resp.Header.Get("Grpc-Header-bar"); value != "bar1" {
+	if value := resp.Header.Get("Grpc-Metadata-bar"); value != "bar1" {
 		t.Errorf("Grpc-Header-bar was %s, wanted %s", value, "bar1")
 	}
 
@@ -427,6 +424,63 @@ func testABELookup(t *testing.T) {
 	if got := msg; !reflect.DeepEqual(got, want) {
 		t.Errorf("msg= %v; want %v", &got, &want)
 	}
+
+	if got, want := resp.Header.Get("Grpc-Metadata-uuid"), want.Uuid; got != want {
+		t.Errorf("Grpc-Metadata-foo was %s, wanted %s", got, want)
+	}
+}
+
+func testABELookupNotFound(t *testing.T) {
+	url := "http://localhost:8080/v1/example/a_bit_of_everything"
+	uuid := "not_exist"
+	url = fmt.Sprintf("%s/%s", url, uuid)
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Errorf("http.Get(%q) failed with %v; want success", url, err)
+		return
+	}
+	defer resp.Body.Close()
+
+	buf, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Errorf("ioutil.ReadAll(resp.Body) failed with %v; want success", err)
+		return
+	}
+
+	if got, want := resp.StatusCode, http.StatusNotFound; got != want {
+		t.Errorf("resp.StatusCode = %d; want %d", got, want)
+		t.Logf("%s", buf)
+		return
+	}
+
+	var msg runtime.ErrorBody
+	if err := json.Unmarshal(buf, &msg); err != nil {
+		t.Errorf("json.Unmarshal(%s, &msg) failed with %v; want success", buf, err)
+		return
+	}
+
+	if got, want := msg.Code, int(codes.NotFound); got != want {
+		t.Errorf("msg.Code = %d; want %d", got, want)
+		return
+	}
+
+	if got, want := resp.Header.Get("Grpc-Metadata-uuid"), uuid; got != want {
+		t.Errorf("Grpc-Metadata-foo was %s, wanted %s", got, want)
+	}
+
+	md := msg.Trailer
+	if md.Len() == 0 {
+		t.Errorf("no trailer is set")
+		return
+	}
+
+	if got, want := md["foo"], []string{"foo2"}; !reflect.DeepEqual(got, want) {
+		t.Errorf("msg.Trailer[%q] = %v; want %v", "foo", got, want)
+	}
+
+	if got, want := md["bar"], []string{"bar2"}; !reflect.DeepEqual(got, want) {
+		t.Errorf("msg.Trailer[%q] = %v; want %v", "bar", got, want)
+	}
 }
 
 func testABEList(t *testing.T) {

examples/server/a_bit_of_everything.go

@@ -83,11 +83,20 @@ func (s *_ABitOfEverythingServer) BulkCreate(stream examples.ABitOfEverythingSer
 func (s *_ABitOfEverythingServer) Lookup(ctx context.Context, msg *examples.IdMessage) (*examples.ABitOfEverything, error) {
 	s.m.Lock()
 	defer s.m.Unlock()
-
 	glog.Info(msg)
+
+	grpc.SendHeader(ctx, metadata.New(map[string]string{
+		"uuid": msg.Uuid,
+	}))
+
 	if a, ok := s.v[msg.Uuid]; ok {
 		return a, nil
 	}
+
+	grpc.SetTrailer(ctx, metadata.New(map[string]string{
+		"foo": "foo2",
+		"bar": "bar2",
+	}))
 	return nil, grpc.Errorf(codes.NotFound, "not found")
 }
 

runtime/errors.go

@@ -2,13 +2,15 @@ package runtime
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
 
 	"github.com/golang/glog"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
 )
 
 // HTTPStatusFromCode converts a gRPC error code into the corresponding HTTP response status.
@@ -62,9 +64,10 @@ var (
 	OtherErrorHandler = DefaultOtherErrorHandler
 )
 
-type errorBody struct {
-	Error string `json:"error"`
-	Code  int    `json:"code"`
+type ErrorBody struct {
+	Error   string      `json:"error"`
+	Code    int         `json:"code"`
+	Trailer metadata.MD `json:"trailer,omitempty"`
 }
 
 // DefaultHTTPError is the default implementation of HTTPError.
@@ -77,7 +80,19 @@ func DefaultHTTPError(ctx context.Context, w http.ResponseWriter, _ *http.Reques
 	const fallback = `{"error": "failed to marshal error message"}`
 
 	w.Header().Set("Content-Type", "application/json")
-	body := errorBody{Error: grpc.ErrorDesc(err), Code: int(grpc.Code(err))}
+	body := ErrorBody{
+		Error: grpc.ErrorDesc(err),
+		Code:  int(grpc.Code(err)),
+	}
+	if md, ok := ServerMetadataFromContext(ctx); ok {
+		for k, vs := range md.HeaderMD {
+			hKey := fmt.Sprintf("%s%s", metadataHeaderPrefix, k)
+			for i := range vs {
+				w.Header().Add(hKey, vs[i])
+			}
+		}
+		body.Trailer = md.TrailerMD
+	}
 	buf, merr := json.Marshal(body)
 	if merr != nil {
 		glog.Errorf("Failed to marshal error message %q: %v", body, merr)

runtime/handler.go

@@ -80,6 +80,20 @@ func ForwardResponseStream(ctx context.Context, w http.ResponseWriter, req *http
 
 // ForwardResponseMessage forwards the message "resp" from gRPC server to REST client.
 func ForwardResponseMessage(ctx context.Context, w http.ResponseWriter, req *http.Request, resp proto.Message, opts ...func(context.Context, http.ResponseWriter, proto.Message) error) {
+	md, ok := ServerMetadataFromContext(ctx)
+	if !ok {
+		glog.Errorf("Failed to extract ServerMetadata from context")
+	}
+
+	if md != nil {
+		for k, vs := range md.HeaderMD {
+			hKey := fmt.Sprintf("%s%s", metadataHeaderPrefix, k)
+			for i := range vs {
+				w.Header().Add(hKey, vs[i])
+			}
+		}
+	}
+
 	w.Header().Set("Content-Type", "application/json")
 	if err := handleForwardResponseOptions(ctx, w, resp, opts); err != nil {
 		HTTPError(ctx, w, req, err)