transport/grpc: add health check (#861)

* add grpc healthcheck

transport/grpc/server.go

@@ -11,8 +11,9 @@ import (
 	"github.com/go-kratos/kratos/v2/middleware"
 	"github.com/go-kratos/kratos/v2/middleware/recovery"
 	"github.com/go-kratos/kratos/v2/transport"
-
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/health"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
 )
 
 const loggerName = "transport/grpc"
@@ -74,6 +75,7 @@ type Server struct {
 	log        *log.Helper
 	middleware middleware.Middleware
 	grpcOpts   []grpc.ServerOption
+	health     *health.Server
 }
 
 // NewServer creates a gRPC server by options.
@@ -86,6 +88,7 @@ func NewServer(opts ...ServerOption) *Server {
 		middleware: middleware.Chain(
 			recovery.Recovery(),
 		),
+		health: health.NewServer(),
 	}
 	for _, o := range opts {
 		o(srv)
@@ -99,6 +102,8 @@ func NewServer(opts ...ServerOption) *Server {
 		grpcOpts = append(grpcOpts, srv.grpcOpts...)
 	}
 	srv.Server = grpc.NewServer(grpcOpts...)
+	// grpc health register
+	healthpb.RegisterHealthServer(srv.Server, srv.health)
 	return srv
 }
 
@@ -121,12 +126,14 @@ func (s *Server) Start() error {
 	}
 	s.lis = lis
 	s.log.Infof("[gRPC] server listening on: %s", lis.Addr().String())
+	s.health.Resume()
 	return s.Serve(lis)
 }
 
 // Stop stop the gRPC server.
 func (s *Server) Stop() error {
 	s.GracefulStop()
+	s.health.Shutdown()
 	s.log.Info("[gRPC] server stopping")
 	return nil
 }