Cherry-pick #1606 against v2

internal/descriptor/registry.go

@@ -84,6 +84,9 @@ type Registry struct {
 	simpleOperationIDs bool
 
 	standalone bool
+	// warnOnUnboundMethods causes the registry to emit warning logs if an RPC method
+	// has no HttpRule annotation.
+	warnOnUnboundMethods bool
 }
 
 type repeatedFieldSeparator struct {
@@ -524,6 +527,11 @@ func (r *Registry) GetSimpleOperationIDs() bool {
 	return r.simpleOperationIDs
 }
 
+// SetWarnOnUnboundMethods sets warnOnUnboundMethods
+func (r *Registry) SetWarnOnUnboundMethods(warn bool) {
+	r.warnOnUnboundMethods = warn
+}
+
 // sanitizePackageName replaces unallowed character in package name
 // with allowed character.
 func sanitizePackageName(pkgName string) string {

internal/descriptor/services.go

@@ -36,7 +36,11 @@ func (r *Registry) loadServices(file *File) error {
 				optsList = append(optsList, opts)
 			}
 			if len(optsList) == 0 {
-				glog.Warningf("No HttpRule found for method: %s.%s", svc.GetName(), md.GetName())
+				logFn := glog.V(1).Infof
+				if  r.warnOnUnboundMethods {
+					logFn = glog.Warningf
+				}
+				logFn("No HttpRule found for method: %s.%s", svc.GetName(), md.GetName())
 			}
 			meth, err := r.newMethod(svc, md, optsList)
 			if err != nil {

protoc-gen-grpc-gateway/main.go

@@ -36,6 +36,7 @@ var (
 	allowPatchFeature          = flag.Bool("allow_patch_feature", true, "determines whether to use PATCH feature involving update masks (using google.protobuf.FieldMask).")
 	standalone                 = flag.Bool("standalone", false, "generates a standalone gateway package, which imports the target service package")
 	versionFlag                = flag.Bool("version", false, "print the current version")
+	warnOnUnboundMethods       = flag.Bool("warn_on_unbound_methods", false, "emit a warning message if an RPC method has no HttpRule annotation")
 )
 
 // Variables set by goreleaser at build time
@@ -96,6 +97,7 @@ func main() {
 	reg.SetImportPath(*importPath)
 	reg.SetAllowDeleteBody(*allowDeleteBody)
 	reg.SetAllowRepeatedFieldsInBody(*allowRepeatedFieldsInBody)
+	reg.SetWarnOnUnboundMethods(*warnOnUnboundMethods)
 	if err := reg.SetRepeatedPathParamSeparator(*repeatedPathParamSeparator); err != nil {
 		emitError(err)
 		return