The JSON encoder/decoder provided by gRPC-gateway runtime silently co…

…nverts (u)int64 to strings (see: grpc-ecosystem/grpc-gateway#920 ),

which is compliant with the Proto3 spec. However, this affects our response negatively because it breaks backwards compatibilty. Go's
JSON encoder/decoder doesn't have such surprises. This commit replaces runtime.JSONPb (from gRPC-Gateway) with a wrapper
around the stdlib JSON encoder/decoder.

grpc/internal/gateway/gateway.go

@@ -8,7 +8,6 @@ import (
 	"io/ioutil"
 	"net/http"
 	"strings"
-	"time"
 
 	log "github.com/sirupsen/logrus"
 
@@ -21,10 +20,13 @@ import (
 
 type GatewayResponseMiddleware func(ctx context.Context, response http.ResponseWriter, m proto.Message) error
 
+func JSONMarshaler() runtime.Marshaler {
+	return new(customJSONMarshaler)
+}
+
 // StatusCodeMutator changes the HTTP Repsonse status code to the desired mapping. The default mapping
 // by gRPC-Gateway doesn't have some of the desired responses (e.g. 201), which is why this function is needed.
 func StatusCodeMutator(ctx context.Context, response http.ResponseWriter, m proto.Message) error {
-	log.Printf("%s: message type: %T", time.Now(), m)
 	switch m.(type) {
 	case *authnpb.SignupResponseEnvelope, *authnpb.LoginResponseEnvelope, *authnpb.RefreshSessionResponseEnvelope, *authnpb.SubmitPasswordlessLoginResponseEnvelope, *authnpb.ChangePasswordResponseEnvelope:
 		response.WriteHeader(http.StatusCreated)

grpc/internal/gateway/marshaler.go

@@ -0,0 +1,36 @@
+package gateway
+
+import (
+	"encoding/json"
+	"io"
+
+	"github.com/grpc-ecosystem/grpc-gateway/runtime"
+)
+
+// customJSONMarshaler implements runtime.Marshaler
+type customJSONMarshaler struct{}
+
+// Marshal marshals "v" into byte sequence.
+func (j *customJSONMarshaler) Marshal(v interface{}) ([]byte, error) {
+	return json.Marshal(v)
+}
+
+// Unmarshal unmarshals "data" into "v".
+func (j *customJSONMarshaler) Unmarshal(data []byte, v interface{}) error {
+	return json.Unmarshal(data, v)
+}
+
+// NewDecoder returns a Decoder which reads byte sequence from "r".
+func (j *customJSONMarshaler) NewDecoder(r io.Reader) runtime.Decoder {
+	return json.NewDecoder(r)
+}
+
+// NewEncoder returns an Encoder which writes bytes sequence into "w".
+func (j *customJSONMarshaler) NewEncoder(w io.Writer) runtime.Encoder {
+	return json.NewEncoder(w)
+}
+
+// ContentType returns the Content-Type which this marshaler is responsible for.
+func (j *customJSONMarshaler) ContentType() string {
+	return "application/json"
+}

grpc/private/gateway.go

@@ -22,10 +22,9 @@ func RunPrivateGateway(ctx context.Context, app *app.App, r *mux.Router, conn *g
 
 	gmux := runtime.NewServeMux(
 		runtime.WithForwardResponseOption(gateway.StatusCodeMutator),
-		runtime.WithMarshalerOption("*", &runtime.JSONPb{
-			OrigName:     true,
-			EmitDefaults: true,
-		}),
+		// Workaround this limitation: https://github.com/grpc-ecosystem/grpc-gateway/issues/920.
+		// Go's JSON encoder doesn't convert (u)int64 to strings silently.
+		runtime.WithMarshalerOption(runtime.MIMEWildcard, gateway.JSONMarshaler()),
 	)
 
 	r.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {

grpc/public/gateway.go

@@ -34,10 +34,9 @@ func RunPublicGateway(ctx context.Context, app *app.App, r *mux.Router, conn *gr
 	gmux := runtime.NewServeMux(
 		runtime.WithForwardResponseOption(gateway.CookieSetter(app.Config)), // Cookies always have to go first
 		runtime.WithForwardResponseOption(gateway.StatusCodeMutator),
-		runtime.WithMarshalerOption("*", &runtime.JSONPb{
-			OrigName:     true,
-			EmitDefaults: true,
-		}),
+		// Workaround this limitation: https://github.com/grpc-ecosystem/grpc-gateway/issues/920.
+		// Go's JSON encoder doesn't convert (u)int64 to strings silently.
+		runtime.WithMarshalerOption(runtime.MIMEWildcard, gateway.JSONMarshaler()),
 	)
 
 	RegisterRoutes(r, app, gmux)