diff --git a/vendor/google.golang.org/grpc/health/client.go b/vendor/google.golang.org/grpc/health/client.go
new file mode 100644
index 0000000..e15f04c
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/client.go
@@ -0,0 +1,107 @@
+/*
+ *
+ * Copyright 2018 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.
+ *
+ */
+
+package health
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/backoff"
+	"google.golang.org/grpc/status"
+)
+
+const maxDelay = 120 * time.Second
+
+var backoffStrategy = backoff.Exponential{MaxDelay: maxDelay}
+var backoffFunc = func(ctx context.Context, retries int) bool {
+	d := backoffStrategy.Backoff(retries)
+	timer := time.NewTimer(d)
+	select {
+	case <-timer.C:
+		return true
+	case <-ctx.Done():
+		timer.Stop()
+		return false
+	}
+}
+
+func init() {
+	internal.HealthCheckFunc = clientHealthCheck
+}
+
+func clientHealthCheck(ctx context.Context, newStream func() (interface{}, error), reportHealth func(bool), service string) error {
+	tryCnt := 0
+
+retryConnection:
+	for {
+		// Backs off if the connection has failed in some way without receiving a message in the previous retry.
+		if tryCnt > 0 && !backoffFunc(ctx, tryCnt-1) {
+			return nil
+		}
+		tryCnt++
+
+		if ctx.Err() != nil {
+			return nil
+		}
+		rawS, err := newStream()
+		if err != nil {
+			continue retryConnection
+		}
+
+		s, ok := rawS.(grpc.ClientStream)
+		// Ideally, this should never happen. But if it happens, the server is marked as healthy for LBing purposes.
+		if !ok {
+			reportHealth(true)
+			return fmt.Errorf("newStream returned %v (type %T); want grpc.ClientStream", rawS, rawS)
+		}
+
+		if err = s.SendMsg(&healthpb.HealthCheckRequest{Service: service}); err != nil && err != io.EOF {
+			// Stream should have been closed, so we can safely continue to create a new stream.
+			continue retryConnection
+		}
+		s.CloseSend()
+
+		resp := new(healthpb.HealthCheckResponse)
+		for {
+			err = s.RecvMsg(resp)
+
+			// Reports healthy for the LBing purposes if health check is not implemented in the server.
+			if status.Code(err) == codes.Unimplemented {
+				reportHealth(true)
+				return err
+			}
+
+			// Reports unhealthy if server's Watch method gives an error other than UNIMPLEMENTED.
+			if err != nil {
+				reportHealth(false)
+				continue retryConnection
+			}
+
+			// As a message has been received, removes the need for backoff for the next retry by reseting the try count.
+			tryCnt = 0
+			reportHealth(resp.Status == healthpb.HealthCheckResponse_SERVING)
+		}
+	}
+}
diff --git a/vendor/google.golang.org/grpc/health/regenerate.sh b/vendor/google.golang.org/grpc/health/regenerate.sh
new file mode 100755
index 0000000..b11eccb
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/regenerate.sh
@@ -0,0 +1,33 @@
+#!/bin/bash
+# Copyright 2018 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.
+
+set -eux -o pipefail
+
+TMP=$(mktemp -d)
+
+function finish {
+  rm -rf "$TMP"
+}
+trap finish EXIT
+
+pushd "$TMP"
+mkdir -p grpc/health/v1
+curl https://raw.githubusercontent.com/grpc/grpc-proto/master/grpc/health/v1/health.proto > grpc/health/v1/health.proto
+
+protoc --go_out=plugins=grpc,paths=source_relative:. -I. grpc/health/v1/*.proto
+popd
+rm -f grpc_health_v1/*.pb.go
+cp "$TMP"/grpc/health/v1/*.pb.go grpc_health_v1/
+
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..c86e499
--- /dev/null
+++ b/vendor/google.golang.org/grpc/health/server.go
@@ -0,0 +1,125 @@
+/*
+ *
+ * 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"
+	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
+	// 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()
+
+	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
+	}
+}