diff --git a/vendor/google.golang.org/grpc/health/server.go b/vendor/google.golang.org/grpc/health/server.go
new file mode 100644
index 0000000..c79f9d2
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/server.go
@@ -0,0 +1,165 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+//go:generate ./regenerate.sh
+
+// Package health provides a service that exposes server's health and it must be
+// imported to enable support for client-side health checks.
+package health
+
+import (
+	"context"
+	"sync"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/grpclog"
+	healthgrpc "google.golang.org/grpc/health/grpc_health_v1"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
+	"google.golang.org/grpc/status"
+)
+
+// Server implements `service Health`.
+type Server struct {
+	mu sync.Mutex
+	// If shutdown is true, it's expected all serving status is NOT_SERVING, and
+	// will stay in NOT_SERVING.
+	shutdown bool
+	// statusMap stores the serving status of the services this Server monitors.
+	statusMap map[string]healthpb.HealthCheckResponse_ServingStatus
+	updates   map[string]map[healthgrpc.Health_WatchServer]chan healthpb.HealthCheckResponse_ServingStatus
+}
+
+// NewServer returns a new Server.
+func NewServer() *Server {
+	return &Server{
+		statusMap: map[string]healthpb.HealthCheckResponse_ServingStatus{"": healthpb.HealthCheckResponse_SERVING},
+		updates:   make(map[string]map[healthgrpc.Health_WatchServer]chan healthpb.HealthCheckResponse_ServingStatus),
+	}
+}
+
+// Check implements `service Health`.
+func (s *Server) Check(ctx context.Context, in *healthpb.HealthCheckRequest) (*healthpb.HealthCheckResponse, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if servingStatus, ok := s.statusMap[in.Service]; ok {
+		return &healthpb.HealthCheckResponse{
+			Status: servingStatus,
+		}, nil
+	}
+	return nil, status.Error(codes.NotFound, "unknown service")
+}
+
+// Watch implements `service Health`.
+func (s *Server) Watch(in *healthpb.HealthCheckRequest, stream healthgrpc.Health_WatchServer) error {
+	service := in.Service
+	// update channel is used for getting service status updates.
+	update := make(chan healthpb.HealthCheckResponse_ServingStatus, 1)
+	s.mu.Lock()
+	// Puts the initial status to the channel.
+	if servingStatus, ok := s.statusMap[service]; ok {
+		update <- servingStatus
+	} else {
+		update <- healthpb.HealthCheckResponse_SERVICE_UNKNOWN
+	}
+
+	// Registers the update channel to the correct place in the updates map.
+	if _, ok := s.updates[service]; !ok {
+		s.updates[service] = make(map[healthgrpc.Health_WatchServer]chan healthpb.HealthCheckResponse_ServingStatus)
+	}
+	s.updates[service][stream] = update
+	defer func() {
+		s.mu.Lock()
+		delete(s.updates[service], stream)
+		s.mu.Unlock()
+	}()
+	s.mu.Unlock()
+
+	var lastSentStatus healthpb.HealthCheckResponse_ServingStatus = -1
+	for {
+		select {
+		// Status updated. Sends the up-to-date status to the client.
+		case servingStatus := <-update:
+			if lastSentStatus == servingStatus {
+				continue
+			}
+			lastSentStatus = servingStatus
+			err := stream.Send(&healthpb.HealthCheckResponse{Status: servingStatus})
+			if err != nil {
+				return status.Error(codes.Canceled, "Stream has ended.")
+			}
+		// Context done. Removes the update channel from the updates map.
+		case <-stream.Context().Done():
+			return status.Error(codes.Canceled, "Stream has ended.")
+		}
+	}
+}
+
+// SetServingStatus is called when need to reset the serving status of a service
+// or insert a new service entry into the statusMap.
+func (s *Server) SetServingStatus(service string, servingStatus healthpb.HealthCheckResponse_ServingStatus) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.shutdown {
+		grpclog.Infof("health: status changing for %s to %v is ignored because health service is shutdown", service, servingStatus)
+		return
+	}
+
+	s.setServingStatusLocked(service, servingStatus)
+}
+
+func (s *Server) setServingStatusLocked(service string, servingStatus healthpb.HealthCheckResponse_ServingStatus) {
+	s.statusMap[service] = servingStatus
+	for _, update := range s.updates[service] {
+		// Clears previous updates, that are not sent to the client, from the channel.
+		// This can happen if the client is not reading and the server gets flow control limited.
+		select {
+		case <-update:
+		default:
+		}
+		// Puts the most recent update to the channel.
+		update <- servingStatus
+	}
+}
+
+// Shutdown sets all serving status to NOT_SERVING, and configures the server to
+// ignore all future status changes.
+//
+// This changes serving status for all services. To set status for a perticular
+// services, call SetServingStatus().
+func (s *Server) Shutdown() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.shutdown = true
+	for service := range s.statusMap {
+		s.setServingStatusLocked(service, healthpb.HealthCheckResponse_NOT_SERVING)
+	}
+}
+
+// Resume sets all serving status to SERVING, and configures the server to
+// accept all future status changes.
+//
+// This changes serving status for all services. To set status for a perticular
+// services, call SetServingStatus().
+func (s *Server) Resume() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.shutdown = false
+	for service := range s.statusMap {
+		s.setServingStatusLocked(service, healthpb.HealthCheckResponse_SERVING)
+	}
+}