runtime/errors: handle error details

Fixes grpc-ecosystem#405.

If we go with this, that is.

In a separate commit, I'll update the generated files.

Signed-off-by: Stephan Renatus <[email protected]>

examples/examplepb/a_bit_of_everything.proto

@@ -204,6 +204,11 @@ service ABitOfEverythingService {
 			get: "/v2/example/timeout",
 		};
 	}
+	rpc ErrorWithDetails(google.protobuf.Empty) returns (google.protobuf.Empty) {
+		option (google.api.http) = {
+			get: "/v2/example/errorwithdetails",
+		};
+	}
 	rpc GetMessageWithBody(MessageWithBody) returns (google.protobuf.Empty) {
 		option (google.api.http) = {
 			post: "/v2/example/withbody/{id}",

examples/integration_test.go

@@ -25,8 +25,9 @@ import (
 )
 
 type errorBody struct {
-	Error string `json:"error"`
-	Code  int    `json:"code"`
+	Error   string        `json:"error"`
+	Code    int           `json:"code"`
+	Details []interface{} `json:"details"`
 }
 
 func TestEcho(t *testing.T) {
@@ -460,7 +461,7 @@ func testABELookupNotFound(t *testing.T, port int) {
 
 	var msg errorBody
 	if err := json.Unmarshal(buf, &msg); err != nil {
-		t.Errorf("jsonpb.UnmarshalString(%s, &msg) failed with %v; want success", buf, err)
+		t.Errorf("json.Unmarshal(%s, &msg) failed with %v; want success", buf, err)
 		return
 	}
 
@@ -723,6 +724,59 @@ func TestTimeout(t *testing.T) {
 	}
 }
 
+func TestErrorWithDetails(t *testing.T) {
+	url := "http://localhost:8080/v2/example/errorwithdetails"
+	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.Fatalf("iotuil.ReadAll(resp.Body) failed with %v; want success", err)
+	}
+
+	if got, want := resp.StatusCode, http.StatusInternalServerError; got != want {
+		t.Errorf("resp.StatusCode = %d; want %d", got, want)
+	}
+
+	var msg errorBody
+	if err := json.Unmarshal(buf, &msg); err != nil {
+		t.Fatalf("json.Unmarshal(%s, &msg) failed with %v; want success", buf, err)
+	}
+
+	if got, want := msg.Code, int(codes.Unknown); got != want {
+		t.Errorf("msg.Code = %d; want %d", got, want)
+	}
+	if got, want := msg.Error, "with details"; got != want {
+		t.Errorf("msg.Error = %s; want %s", got, want)
+	}
+	if got, want := len(msg.Details), 1; got != want {
+		t.Fatalf("len(msg.Details) = %q; want %q", got, want)
+	}
+
+	details, ok := msg.Details[0].(map[string]interface{})
+	if got, want := ok, true; got != want {
+		t.Fatalf("msg.Details[0] got type: %T, want %T", msg.Details[0], map[string]interface{}{})
+	}
+	if got, want := details["detail"], "error debug details"; got != want {
+		t.Errorf("msg.Details[\"detail\"] = %q; want %q", got, want)
+	}
+	entries, ok := details["stack_entries"].([]interface{})
+	if got, want := ok, true; got != want {
+		t.Fatalf("msg.Details[0][\"stack_entries\"] got type: %T, want %T", entries, []string{})
+	}
+	entry, ok := entries[0].(string)
+	if got, want := ok, true; got != want {
+		t.Fatalf("msg.Details[0][\"stack_entries\"][0] got type: %T, want %T", entry, "")
+	}
+	if got, want := entries[0], "foo:1"; got != want {
+		t.Errorf("msg.Details[\"stack_entries\"][0] = %q; want %q", got, want)
+	}
+}
+
 func TestUnknownPath(t *testing.T) {
 	url := "http://localhost:8080"
 	resp, err := http.Post(url, "application/json", strings.NewReader("{}"))

examples/server/a_bit_of_everything.go

@@ -6,18 +6,19 @@ import (
 	"sync"
 
 	"github.com/golang/glog"
+	"github.com/golang/protobuf/proto"
 	"github.com/golang/protobuf/ptypes/duration"
 	"github.com/golang/protobuf/ptypes/empty"
 	examples "github.com/grpc-ecosystem/grpc-gateway/examples/examplepb"
 	sub "github.com/grpc-ecosystem/grpc-gateway/examples/sub"
 	sub2 "github.com/grpc-ecosystem/grpc-gateway/examples/sub2"
 	"github.com/rogpeppe/fastuuid"
 	"golang.org/x/net/context"
+	"google.golang.org/genproto/googleapis/rpc/errdetails"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
-
 )
 
 // Implements of ABitOfEverythingServiceServer
@@ -248,6 +249,21 @@ func (s *_ABitOfEverythingServer) Timeout(ctx context.Context, msg *empty.Empty)
 	}
 }
 
+func (s *_ABitOfEverythingServer) ErrorWithDetails(ctx context.Context, msg *empty.Empty) (*empty.Empty, error) {
+	stat := status.New(codes.Unknown, "with details")
+	details := []proto.Message{
+		&errdetails.DebugInfo{
+			StackEntries: []string{"foo:1"},
+			Detail:       "error debug details",
+		},
+	}
+	stat, err := stat.WithDetails(details...)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "unexpected error adding details: %s", err)
+	}
+	return nil, stat.Err()
+}
+
 func (s *_ABitOfEverythingServer) GetMessageWithBody(ctx context.Context, msg *examples.MessageWithBody) (*empty.Empty, error) {
 	return &empty.Empty{}, nil
 }

runtime/errors.go

@@ -63,11 +63,12 @@ var (
 )
 
 type errorBody struct {
-	Error string `protobuf:"bytes,1,name=error" json:"error"`
-	Code  int32  `protobuf:"varint,2,name=code" json:"code"`
+	Error   string          `protobuf:"bytes,1,name=error" json:"error"`
+	Code    int32           `protobuf:"varint,2,name=code" json:"code"`
+	Details []proto.Message `protobuf:"bytes,3,name=details" json:"details"`
 }
 
-//Make this also conform to proto.Message for builtin JSONPb Marshaler
+// Make this also conform to proto.Message for builtin JSONPb Marshaler
 func (e *errorBody) Reset()         { *e = errorBody{} }
 func (e *errorBody) String() string { return proto.CompactTextString(e) }
 func (*errorBody) ProtoMessage()    {}
@@ -94,6 +95,12 @@ func DefaultHTTPError(ctx context.Context, mux *ServeMux, marshaler Marshaler, w
 		Code:  int32(s.Code()),
 	}
 
+	for _, detail := range s.Details() {
+		if det, ok := detail.(proto.Message); ok {
+			body.Details = append(body.Details, det)
+		}
+	}
+
 	buf, merr := marshaler.Marshal(body)
 	if merr != nil {
 		grpclog.Printf("Failed to marshal error message %q: %v", body, merr)