add api metadata (#901)

* add api metadata

api/kratos/api/metadata.pb.go

@@ -0,0 +1,305 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.26.0
+// 	protoc        v3.15.8
+// source: metadata.proto
+
+package api
+
+import (
+	_ "google.golang.org/genproto/googleapis/api/annotations"
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	descriptorpb "google.golang.org/protobuf/types/descriptorpb"
+	anypb "google.golang.org/protobuf/types/known/anypb"
+	reflect "reflect"
+	sync "sync"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+type ListServicesReply struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Services []string `protobuf:"bytes,1,rep,name=services,proto3" json:"services,omitempty"`
+}
+
+func (x *ListServicesReply) Reset() {
+	*x = ListServicesReply{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_metadata_proto_msgTypes[0]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *ListServicesReply) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListServicesReply) ProtoMessage() {}
+
+func (x *ListServicesReply) ProtoReflect() protoreflect.Message {
+	mi := &file_metadata_proto_msgTypes[0]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListServicesReply.ProtoReflect.Descriptor instead.
+func (*ListServicesReply) Descriptor() ([]byte, []int) {
+	return file_metadata_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *ListServicesReply) GetServices() []string {
+	if x != nil {
+		return x.Services
+	}
+	return nil
+}
+
+type GetServiceMetaRequest struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+}
+
+func (x *GetServiceMetaRequest) Reset() {
+	*x = GetServiceMetaRequest{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_metadata_proto_msgTypes[1]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *GetServiceMetaRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*GetServiceMetaRequest) ProtoMessage() {}
+
+func (x *GetServiceMetaRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_metadata_proto_msgTypes[1]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use GetServiceMetaRequest.ProtoReflect.Descriptor instead.
+func (*GetServiceMetaRequest) Descriptor() ([]byte, []int) {
+	return file_metadata_proto_rawDescGZIP(), []int{1}
+}
+
+func (x *GetServiceMetaRequest) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
+}
+
+type GetServiceMetaReply struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	ProtoSet *descriptorpb.FileDescriptorSet `protobuf:"bytes,1,opt,name=protoSet,proto3" json:"protoSet,omitempty"`
+}
+
+func (x *GetServiceMetaReply) Reset() {
+	*x = GetServiceMetaReply{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_metadata_proto_msgTypes[2]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *GetServiceMetaReply) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*GetServiceMetaReply) ProtoMessage() {}
+
+func (x *GetServiceMetaReply) ProtoReflect() protoreflect.Message {
+	mi := &file_metadata_proto_msgTypes[2]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use GetServiceMetaReply.ProtoReflect.Descriptor instead.
+func (*GetServiceMetaReply) Descriptor() ([]byte, []int) {
+	return file_metadata_proto_rawDescGZIP(), []int{2}
+}
+
+func (x *GetServiceMetaReply) GetProtoSet() *descriptorpb.FileDescriptorSet {
+	if x != nil {
+		return x.ProtoSet
+	}
+	return nil
+}
+
+var File_metadata_proto protoreflect.FileDescriptor
+
+var file_metadata_proto_rawDesc = []byte{
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+	0x41, 0x50, 0x49, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
+}
+
+var (
+	file_metadata_proto_rawDescOnce sync.Once
+	file_metadata_proto_rawDescData = file_metadata_proto_rawDesc
+)
+
+func file_metadata_proto_rawDescGZIP() []byte {
+	file_metadata_proto_rawDescOnce.Do(func() {
+		file_metadata_proto_rawDescData = protoimpl.X.CompressGZIP(file_metadata_proto_rawDescData)
+	})
+	return file_metadata_proto_rawDescData
+}
+
+var file_metadata_proto_msgTypes = make([]protoimpl.MessageInfo, 3)
+var file_metadata_proto_goTypes = []interface{}{
+	(*ListServicesReply)(nil),              // 0: kratos.api.ListServicesReply
+	(*GetServiceMetaRequest)(nil),          // 1: kratos.api.GetServiceMetaRequest
+	(*GetServiceMetaReply)(nil),            // 2: kratos.api.GetServiceMetaReply
+	(*descriptorpb.FileDescriptorSet)(nil), // 3: google.protobuf.FileDescriptorSet
+	(*anypb.Any)(nil),                      // 4: google.protobuf.Any
+}
+var file_metadata_proto_depIdxs = []int32{
+	3, // 0: kratos.api.GetServiceMetaReply.protoSet:type_name -> google.protobuf.FileDescriptorSet
+	4, // 1: kratos.api.Metadata.ListServices:input_type -> google.protobuf.Any
+	1, // 2: kratos.api.Metadata.GetServiceMeta:input_type -> kratos.api.GetServiceMetaRequest
+	0, // 3: kratos.api.Metadata.ListServices:output_type -> kratos.api.ListServicesReply
+	2, // 4: kratos.api.Metadata.GetServiceMeta:output_type -> kratos.api.GetServiceMetaReply
+	3, // [3:5] is the sub-list for method output_type
+	1, // [1:3] is the sub-list for method input_type
+	1, // [1:1] is the sub-list for extension type_name
+	1, // [1:1] is the sub-list for extension extendee
+	0, // [0:1] is the sub-list for field type_name
+}
+
+func init() { file_metadata_proto_init() }
+func file_metadata_proto_init() {
+	if File_metadata_proto != nil {
+		return
+	}
+	if !protoimpl.UnsafeEnabled {
+		file_metadata_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*ListServicesReply); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_metadata_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*GetServiceMetaRequest); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_metadata_proto_msgTypes[2].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*GetServiceMetaReply); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: file_metadata_proto_rawDesc,
+			NumEnums:      0,
+			NumMessages:   3,
+			NumExtensions: 0,
+			NumServices:   1,
+		},
+		GoTypes:           file_metadata_proto_goTypes,
+		DependencyIndexes: file_metadata_proto_depIdxs,
+		MessageInfos:      file_metadata_proto_msgTypes,
+	}.Build()
+	File_metadata_proto = out.File
+	file_metadata_proto_rawDesc = nil
+	file_metadata_proto_goTypes = nil
+	file_metadata_proto_depIdxs = nil
+}

api/kratos/api/metadata.proto

@@ -0,0 +1,43 @@
+syntax = "proto3";
+
+package kratos.api;
+
+import "google/protobuf/any.proto";
+import "google/protobuf/descriptor.proto";
+import "google/api/annotations.proto";
+
+option go_package = "github.com/go-kratos/kratos/v2/api/kratos/api;api";
+option java_multiple_files = true;
+option java_package = "com.github.kratos.api";
+option objc_class_prefix = "KratosAPI";
+
+
+// Metadata is api defintion metadata service
+service Metadata {
+  // ListServices list the full name of all services
+  rpc ListServices (google.protobuf.Any) returns (ListServicesReply)  {
+      option (google.api.http) = {
+        get: "/services",
+      };
+  }
+
+  // GetServiceMeta get the full fileDescriptorSet of service
+  rpc GetServiceMeta (GetServiceMetaRequest) returns (GetServiceMetaReply)  {
+      option (google.api.http) = {
+        get: "/service/{name}/metadata",
+      };
+  }
+}
+
+message ListServicesReply {
+  repeated string services = 1;
+}
+
+message GetServiceMetaRequest {
+  string name = 1;
+}
+
+message GetServiceMetaReply {
+  google.protobuf.FileDescriptorSet protoSet = 1;
+}
+

api/kratos/api/metadata_grpc.pb.go

@@ -0,0 +1,146 @@
+// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
+// versions:
+// - protoc-gen-go-grpc v1.1.0
+// - protoc             v3.15.8
+// source: metadata.proto
+
+package api
+
+import (
+	context "context"
+	grpc "google.golang.org/grpc"
+	codes "google.golang.org/grpc/codes"
+	status "google.golang.org/grpc/status"
+	anypb "google.golang.org/protobuf/types/known/anypb"
+)
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+// Requires gRPC-Go v1.32.0 or later.
+const _ = grpc.SupportPackageIsVersion7
+
+// MetadataClient is the client API for Metadata service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
+type MetadataClient interface {
+	// ListServices list the full name of all services
+	ListServices(ctx context.Context, in *anypb.Any, opts ...grpc.CallOption) (*ListServicesReply, error)
+	// GetServiceMeta get the full fileDescriptorSet of service
+	GetServiceMeta(ctx context.Context, in *GetServiceMetaRequest, opts ...grpc.CallOption) (*GetServiceMetaReply, error)
+}
+
+type metadataClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewMetadataClient(cc grpc.ClientConnInterface) MetadataClient {
+	return &metadataClient{cc}
+}
+
+func (c *metadataClient) ListServices(ctx context.Context, in *anypb.Any, opts ...grpc.CallOption) (*ListServicesReply, error) {
+	out := new(ListServicesReply)
+	err := c.cc.Invoke(ctx, "/kratos.api.Metadata/ListServices", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *metadataClient) GetServiceMeta(ctx context.Context, in *GetServiceMetaRequest, opts ...grpc.CallOption) (*GetServiceMetaReply, error) {
+	out := new(GetServiceMetaReply)
+	err := c.cc.Invoke(ctx, "/kratos.api.Metadata/GetServiceMeta", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// MetadataServer is the server API for Metadata service.
+// All implementations must embed UnimplementedMetadataServer
+// for forward compatibility
+type MetadataServer interface {
+	// ListServices list the full name of all services
+	ListServices(context.Context, *anypb.Any) (*ListServicesReply, error)
+	// GetServiceMeta get the full fileDescriptorSet of service
+	GetServiceMeta(context.Context, *GetServiceMetaRequest) (*GetServiceMetaReply, error)
+	mustEmbedUnimplementedMetadataServer()
+}
+
+// UnimplementedMetadataServer must be embedded to have forward compatible implementations.
+type UnimplementedMetadataServer struct {
+}
+
+func (UnimplementedMetadataServer) ListServices(context.Context, *anypb.Any) (*ListServicesReply, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method ListServices not implemented")
+}
+func (UnimplementedMetadataServer) GetServiceMeta(context.Context, *GetServiceMetaRequest) (*GetServiceMetaReply, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method GetServiceMeta not implemented")
+}
+func (UnimplementedMetadataServer) mustEmbedUnimplementedMetadataServer() {}
+
+// UnsafeMetadataServer may be embedded to opt out of forward compatibility for this service.
+// Use of this interface is not recommended, as added methods to MetadataServer will
+// result in compilation errors.
+type UnsafeMetadataServer interface {
+	mustEmbedUnimplementedMetadataServer()
+}
+
+func RegisterMetadataServer(s grpc.ServiceRegistrar, srv MetadataServer) {
+	s.RegisterService(&Metadata_ServiceDesc, srv)
+}
+
+func _Metadata_ListServices_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(anypb.Any)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MetadataServer).ListServices(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/kratos.api.Metadata/ListServices",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MetadataServer).ListServices(ctx, req.(*anypb.Any))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _Metadata_GetServiceMeta_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(GetServiceMetaRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(MetadataServer).GetServiceMeta(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/kratos.api.Metadata/GetServiceMeta",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(MetadataServer).GetServiceMeta(ctx, req.(*GetServiceMetaRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+// Metadata_ServiceDesc is the grpc.ServiceDesc for Metadata service.
+// It's only intended for direct use with grpc.RegisterService,
+// and not to be introspected or modified (even as a copy)
+var Metadata_ServiceDesc = grpc.ServiceDesc{
+	ServiceName: "kratos.api.Metadata",
+	HandlerType: (*MetadataServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "ListServices",
+			Handler:    _Metadata_ListServices_Handler,
+		},
+		{
+			MethodName: "GetServiceMeta",
+			Handler:    _Metadata_GetServiceMeta_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "metadata.proto",
+}

api/kratos/api/metadata_http.pb.go

@@ -0,0 +1,90 @@
+// Code generated by protoc-gen-go-http. DO NOT EDIT.
+
+package api
+
+import (
+	context "context"
+	http1 "github.com/go-kratos/kratos/v2/transport/http"
+	binding "github.com/go-kratos/kratos/v2/transport/http/binding"
+	mux "github.com/gorilla/mux"
+	anypb "google.golang.org/protobuf/types/known/anypb"
+	http "net/http"
+)
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the kratos package it is being compiled against.
+var _ = new(http.Request)
+var _ = new(context.Context)
+var _ = binding.MapProto
+var _ = mux.NewRouter
+
+const _ = http1.SupportPackageIsVersion1
+
+type MetadataHandler interface {
+	GetServiceMeta(context.Context, *GetServiceMetaRequest) (*GetServiceMetaReply, error)
+
+	ListServices(context.Context, *anypb.Any) (*ListServicesReply, error)
+}
+
+func NewMetadataHandler(srv MetadataHandler, opts ...http1.HandleOption) http.Handler {
+	h := http1.DefaultHandleOptions()
+	for _, o := range opts {
+		o(&h)
+	}
+	r := mux.NewRouter()
+
+	r.HandleFunc("/services", func(w http.ResponseWriter, r *http.Request) {
+		var in anypb.Any
+		if err := h.Decode(r, &in); err != nil {
+			h.Error(w, r, err)
+			return
+		}
+
+		next := func(ctx context.Context, req interface{}) (interface{}, error) {
+			return srv.ListServices(ctx, req.(*anypb.Any))
+		}
+		if h.Middleware != nil {
+			next = h.Middleware(next)
+		}
+		out, err := next(r.Context(), &in)
+		if err != nil {
+			h.Error(w, r, err)
+			return
+		}
+		reply := out.(*ListServicesReply)
+		if err := h.Encode(w, r, reply); err != nil {
+			h.Error(w, r, err)
+		}
+	}).Methods("GET")
+
+	r.HandleFunc("/service/{name}/metadata", func(w http.ResponseWriter, r *http.Request) {
+		var in GetServiceMetaRequest
+		if err := h.Decode(r, &in); err != nil {
+			h.Error(w, r, err)
+			return
+		}
+
+		if err := binding.MapProto(&in, mux.Vars(r)); err != nil {
+			h.Error(w, r, err)
+			return
+		}
+
+		next := func(ctx context.Context, req interface{}) (interface{}, error) {
+			return srv.GetServiceMeta(ctx, req.(*GetServiceMetaRequest))
+		}
+		if h.Middleware != nil {
+			next = h.Middleware(next)
+		}
+		out, err := next(r.Context(), &in)
+		if err != nil {
+			h.Error(w, r, err)
+			return
+		}
+		reply := out.(*GetServiceMetaReply)
+		if err := h.Encode(w, r, reply); err != nil {
+			h.Error(w, r, err)
+		}
+	}).Methods("GET")
+
+	return r
+}

internal/api/metadata/server.go

@@ -0,0 +1,36 @@
+package metadata
+
+import (
+	"context"
+
+	"github.com/go-kratos/kratos/v2/api/kratos/api"
+	"google.golang.org/grpc"
+	anypb "google.golang.org/protobuf/types/known/anypb"
+)
+
+// Server is api meta server
+type Server struct {
+	api.UnimplementedMetadataServer
+	s *Service
+}
+
+// NewServer create server instance
+func NewServer(grpcSrv ...*grpc.Server) *Server {
+	return &Server{s: NewService(grpcSrv...)}
+}
+
+// ListServices return all services
+func (s *Server) ListServices(ctx context.Context, in *anypb.Any) (*api.ListServicesReply, error) {
+	var reply api.ListServicesReply
+	var err error
+	reply.Services, err = s.s.ListServices(ctx)
+	return &reply, err
+}
+
+// GetServiceMeta return service meta by name
+func (s *Server) GetServiceMeta(ctx context.Context, in *api.GetServiceMetaRequest) (*api.GetServiceMetaReply, error) {
+	var reply api.GetServiceMetaReply
+	var err error
+	reply.ProtoSet, err = s.s.GetServiceMeta(ctx, in.Name)
+	return &reply, err
+}

internal/api/metadata/service.go

@@ -0,0 +1,182 @@
+package metadata
+
+import (
+	"bytes"
+	"compress/gzip"
+	"context"
+	"fmt"
+	"io/ioutil"
+	"sync"
+
+	"github.com/golang/protobuf/proto"
+	dpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
+	"google.golang.org/grpc"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+	"google.golang.org/protobuf/types/descriptorpb"
+)
+
+// Service is description service
+type Service struct {
+	grpcSer  *grpc.Server
+	once     sync.Once
+	services map[string]*descriptorpb.FileDescriptorSet
+}
+
+// NewService create desc Service
+func NewService(grpcSrv ...*grpc.Server) *Service {
+	s := &Service{}
+	if len(grpcSrv) > 0 {
+		s.grpcSer = grpcSrv[0]
+	}
+	return s
+}
+
+// ListServices list the full name of all services
+func (s *Service) ListServices(ctx context.Context) (services []string, err error) {
+	services = []string{}
+	s.once.Do(func() {
+		err = s.initServices()
+	})
+	for name := range s.services {
+		services = append(services, name)
+	}
+	return
+}
+
+// GetServiceMeta get the full fileDescriptorSet of service
+func (s *Service) GetServiceMeta(ctx context.Context, name string) (fds *descriptorpb.FileDescriptorSet, err error) {
+	fds = &descriptorpb.FileDescriptorSet{}
+	s.once.Do(func() {
+		err = s.initServices()
+	})
+	if temp, ok := s.services[name]; ok {
+		fds = temp
+	}
+	return
+}
+
+func (s *Service) initServices() error {
+	serviceProto, err := s.listServices()
+	if err != nil {
+		s.services = make(map[string]*descriptorpb.FileDescriptorSet)
+		return err
+	}
+	s.services = serviceProto
+	return nil
+}
+
+func (s *Service) listServices() (map[string]*descriptorpb.FileDescriptorSet, error) {
+	services := make(map[string]*descriptorpb.FileDescriptorSet, 0)
+	if s.grpcSer != nil {
+		for svc, info := range s.grpcSer.GetServiceInfo() {
+			fdenc, ok := parseMetadata(info.Metadata)
+			if !ok {
+				return nil, fmt.Errorf("invalid service %s meta", svc)
+			}
+			fd, err := decodeFileDesc(fdenc)
+			if err != nil {
+				return nil, err
+			}
+			protoSet, err := allDependency(fd)
+			if err != nil {
+				return nil, err
+			}
+			services[svc] = &dpb.FileDescriptorSet{File: protoSet}
+		}
+		return services, nil
+	}
+	var err error
+	protoregistry.GlobalFiles.RangeFiles(func(fd protoreflect.FileDescriptor) bool {
+		if fd.Services() != nil && fd.Services().Len() > 0 {
+			for i := 0; i < fd.Services().Len(); i++ {
+				svc := string(fd.Services().Get(i).FullName())
+				fdp, e := fileDescriptorProto(fd.Path())
+				if e != nil {
+					err = e
+					return false
+				}
+				fdps, e := allDependency(fdp)
+				if e != nil {
+					err = e
+					return false
+				}
+				services[svc] = &dpb.FileDescriptorSet{File: fdps}
+			}
+		}
+		return true
+	})
+	return services, err
+}
+
+func fileDescriptorProto(path string) (*dpb.FileDescriptorProto, error) {
+	fdenc := proto.FileDescriptor(path)
+	fdDep, err := decodeFileDesc(fdenc)
+	if err != nil {
+		return nil, err
+	}
+	return fdDep, nil
+}
+
+func allDependency(fd *dpb.FileDescriptorProto) ([]*dpb.FileDescriptorProto, error) {
+	var files []*dpb.FileDescriptorProto
+	files = append(files, fd)
+	for _, dep := range fd.Dependency {
+		fdDep, err := fileDescriptorProto(dep)
+		if err != nil {
+			return nil, err
+		}
+		temp, err := allDependency(fdDep)
+		if err != nil {
+			return nil, err
+		}
+		files = append(files, temp...)
+	}
+	return files, nil
+}
+
+// parseMetadata finds the file descriptor bytes specified meta.
+// For SupportPackageIsVersion4, m is the name of the proto file, we
+// call proto.FileDescriptor to get the byte slice.
+// For SupportPackageIsVersion3, m is a byte slice itself.
+func parseMetadata(meta interface{}) ([]byte, bool) {
+	// Check if meta is the file name.
+	if fileNameForMeta, ok := meta.(string); ok {
+		return proto.FileDescriptor(fileNameForMeta), true
+	}
+
+	// Check if meta is the byte slice.
+	if enc, ok := meta.([]byte); ok {
+		return enc, true
+	}
+
+	return nil, false
+}
+
+// decodeFileDesc does decompression and unmarshalling on the given
+// file descriptor byte slice.
+func decodeFileDesc(enc []byte) (*dpb.FileDescriptorProto, error) {
+	raw, err := decompress(enc)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decompress enc: %v", err)
+	}
+
+	fd := new(dpb.FileDescriptorProto)
+	if err := proto.Unmarshal(raw, fd); err != nil {
+		return nil, fmt.Errorf("bad descriptor: %v", err)
+	}
+	return fd, nil
+}
+
+// decompress does gzip decompression.
+func decompress(b []byte) ([]byte, error) {
+	r, err := gzip.NewReader(bytes.NewReader(b))
+	if err != nil {
+		return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
+	}
+	out, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
+	}
+	return out, nil
+}

transport/grpc/server.go

@@ -6,6 +6,8 @@ import (
 	"net"
 	"time"
 
+	"github.com/go-kratos/kratos/v2/api/kratos/api"
+	"github.com/go-kratos/kratos/v2/internal/api/metadata"
 	"github.com/go-kratos/kratos/v2/internal/host"
 	"github.com/go-kratos/kratos/v2/log"
 	"github.com/go-kratos/kratos/v2/middleware"
@@ -77,6 +79,7 @@ type Server struct {
 	middleware middleware.Middleware
 	grpcOpts   []grpc.ServerOption
 	health     *health.Server
+	metaServer *metadata.Server
 }
 
 // NewServer creates a gRPC server by options.
@@ -103,8 +106,11 @@ func NewServer(opts ...ServerOption) *Server {
 		grpcOpts = append(grpcOpts, srv.grpcOpts...)
 	}
 	srv.Server = grpc.NewServer(grpcOpts...)
+	srv.metaServer = metadata.NewServer(srv.Server)
 	// grpc health register
 	healthpb.RegisterHealthServer(srv.Server, srv.health)
+	// api metadata register
+	api.RegisterMetadataServer(srv.Server, srv.metaServer)
 	// reflection register
 	reflection.Register(srv.Server)
 	return srv