diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/watch.go b/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/watch.go
new file mode 100644
index 0000000..f41cb6c
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/watch.go
@@ -0,0 +1,584 @@
+// Copyright 2015 The etcd 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 v3rpc
+
+import (
+	"context"
+	"io"
+	"math/rand"
+	"sync"
+	"time"
+
+	"go.etcd.io/etcd/auth"
+	"go.etcd.io/etcd/etcdserver"
+	"go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
+	pb "go.etcd.io/etcd/etcdserver/etcdserverpb"
+	"go.etcd.io/etcd/mvcc"
+	"go.etcd.io/etcd/mvcc/mvccpb"
+
+	"go.uber.org/zap"
+)
+
+type watchServer struct {
+	lg *zap.Logger
+
+	clusterID int64
+	memberID  int64
+
+	maxRequestBytes int
+
+	sg        etcdserver.RaftStatusGetter
+	watchable mvcc.WatchableKV
+	ag        AuthGetter
+}
+
+// NewWatchServer returns a new watch server.
+func NewWatchServer(s *etcdserver.EtcdServer) pb.WatchServer {
+	return &watchServer{
+		lg: s.Cfg.Logger,
+
+		clusterID: int64(s.Cluster().ID()),
+		memberID:  int64(s.ID()),
+
+		maxRequestBytes: int(s.Cfg.MaxRequestBytes + grpcOverheadBytes),
+
+		sg:        s,
+		watchable: s.Watchable(),
+		ag:        s,
+	}
+}
+
+var (
+	// External test can read this with GetProgressReportInterval()
+	// and change this to a small value to finish fast with
+	// SetProgressReportInterval().
+	progressReportInterval   = 10 * time.Minute
+	progressReportIntervalMu sync.RWMutex
+)
+
+// GetProgressReportInterval returns the current progress report interval (for testing).
+func GetProgressReportInterval() time.Duration {
+	progressReportIntervalMu.RLock()
+	interval := progressReportInterval
+	progressReportIntervalMu.RUnlock()
+
+	// add rand(1/10*progressReportInterval) as jitter so that etcdserver will not
+	// send progress notifications to watchers around the same time even when watchers
+	// are created around the same time (which is common when a client restarts itself).
+	jitter := time.Duration(rand.Int63n(int64(interval) / 10))
+
+	return interval + jitter
+}
+
+// SetProgressReportInterval updates the current progress report interval (for testing).
+func SetProgressReportInterval(newTimeout time.Duration) {
+	progressReportIntervalMu.Lock()
+	progressReportInterval = newTimeout
+	progressReportIntervalMu.Unlock()
+}
+
+// We send ctrl response inside the read loop. We do not want
+// send to block read, but we still want ctrl response we sent to
+// be serialized. Thus we use a buffered chan to solve the problem.
+// A small buffer should be OK for most cases, since we expect the
+// ctrl requests are infrequent.
+const ctrlStreamBufLen = 16
+
+// serverWatchStream is an etcd server side stream. It receives requests
+// from client side gRPC stream. It receives watch events from mvcc.WatchStream,
+// and creates responses that forwarded to gRPC stream.
+// It also forwards control message like watch created and canceled.
+type serverWatchStream struct {
+	lg *zap.Logger
+
+	clusterID int64
+	memberID  int64
+
+	maxRequestBytes int
+
+	sg        etcdserver.RaftStatusGetter
+	watchable mvcc.WatchableKV
+	ag        AuthGetter
+
+	gRPCStream  pb.Watch_WatchServer
+	watchStream mvcc.WatchStream
+	ctrlStream  chan *pb.WatchResponse
+
+	// mu protects progress, prevKV, fragment
+	mu sync.RWMutex
+	// tracks the watchID that stream might need to send progress to
+	// TODO: combine progress and prevKV into a single struct?
+	progress map[mvcc.WatchID]bool
+	// record watch IDs that need return previous key-value pair
+	prevKV map[mvcc.WatchID]bool
+	// records fragmented watch IDs
+	fragment map[mvcc.WatchID]bool
+
+	// closec indicates the stream is closed.
+	closec chan struct{}
+
+	// wg waits for the send loop to complete
+	wg sync.WaitGroup
+}
+
+func (ws *watchServer) Watch(stream pb.Watch_WatchServer) (err error) {
+	sws := serverWatchStream{
+		lg: ws.lg,
+
+		clusterID: ws.clusterID,
+		memberID:  ws.memberID,
+
+		maxRequestBytes: ws.maxRequestBytes,
+
+		sg:        ws.sg,
+		watchable: ws.watchable,
+		ag:        ws.ag,
+
+		gRPCStream:  stream,
+		watchStream: ws.watchable.NewWatchStream(),
+		// chan for sending control response like watcher created and canceled.
+		ctrlStream: make(chan *pb.WatchResponse, ctrlStreamBufLen),
+
+		progress: make(map[mvcc.WatchID]bool),
+		prevKV:   make(map[mvcc.WatchID]bool),
+		fragment: make(map[mvcc.WatchID]bool),
+
+		closec: make(chan struct{}),
+	}
+
+	sws.wg.Add(1)
+	go func() {
+		sws.sendLoop()
+		sws.wg.Done()
+	}()
+
+	errc := make(chan error, 1)
+	// Ideally recvLoop would also use sws.wg to signal its completion
+	// but when stream.Context().Done() is closed, the stream's recv
+	// may continue to block since it uses a different context, leading to
+	// deadlock when calling sws.close().
+	go func() {
+		if rerr := sws.recvLoop(); rerr != nil {
+			if isClientCtxErr(stream.Context().Err(), rerr) {
+				if sws.lg != nil {
+					sws.lg.Debug("failed to receive watch request from gRPC stream", zap.Error(rerr))
+				} else {
+					plog.Debugf("failed to receive watch request from gRPC stream (%q)", rerr.Error())
+				}
+			} else {
+				if sws.lg != nil {
+					sws.lg.Warn("failed to receive watch request from gRPC stream", zap.Error(rerr))
+				} else {
+					plog.Warningf("failed to receive watch request from gRPC stream (%q)", rerr.Error())
+				}
+				streamFailures.WithLabelValues("receive", "watch").Inc()
+			}
+			errc <- rerr
+		}
+	}()
+
+	select {
+	case err = <-errc:
+		close(sws.ctrlStream)
+
+	case <-stream.Context().Done():
+		err = stream.Context().Err()
+		// the only server-side cancellation is noleader for now.
+		if err == context.Canceled {
+			err = rpctypes.ErrGRPCNoLeader
+		}
+	}
+
+	sws.close()
+	return err
+}
+
+func (sws *serverWatchStream) isWatchPermitted(wcr *pb.WatchCreateRequest) bool {
+	authInfo, err := sws.ag.AuthInfoFromCtx(sws.gRPCStream.Context())
+	if err != nil {
+		return false
+	}
+	if authInfo == nil {
+		// if auth is enabled, IsRangePermitted() can cause an error
+		authInfo = &auth.AuthInfo{}
+	}
+	return sws.ag.AuthStore().IsRangePermitted(authInfo, wcr.Key, wcr.RangeEnd) == nil
+}
+
+func (sws *serverWatchStream) recvLoop() error {
+	for {
+		req, err := sws.gRPCStream.Recv()
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+
+		switch uv := req.RequestUnion.(type) {
+		case *pb.WatchRequest_CreateRequest:
+			if uv.CreateRequest == nil {
+				break
+			}
+
+			creq := uv.CreateRequest
+			if len(creq.Key) == 0 {
+				// \x00 is the smallest key
+				creq.Key = []byte{0}
+			}
+			if len(creq.RangeEnd) == 0 {
+				// force nil since watchstream.Watch distinguishes
+				// between nil and []byte{} for single key / >=
+				creq.RangeEnd = nil
+			}
+			if len(creq.RangeEnd) == 1 && creq.RangeEnd[0] == 0 {
+				// support  >= key queries
+				creq.RangeEnd = []byte{}
+			}
+
+			if !sws.isWatchPermitted(creq) {
+				wr := &pb.WatchResponse{
+					Header:       sws.newResponseHeader(sws.watchStream.Rev()),
+					WatchId:      creq.WatchId,
+					Canceled:     true,
+					Created:      true,
+					CancelReason: rpctypes.ErrGRPCPermissionDenied.Error(),
+				}
+
+				select {
+				case sws.ctrlStream <- wr:
+				case <-sws.closec:
+				}
+				return nil
+			}
+
+			filters := FiltersFromRequest(creq)
+
+			wsrev := sws.watchStream.Rev()
+			rev := creq.StartRevision
+			if rev == 0 {
+				rev = wsrev + 1
+			}
+			id, err := sws.watchStream.Watch(mvcc.WatchID(creq.WatchId), creq.Key, creq.RangeEnd, rev, filters...)
+			if err == nil {
+				sws.mu.Lock()
+				if creq.ProgressNotify {
+					sws.progress[id] = true
+				}
+				if creq.PrevKv {
+					sws.prevKV[id] = true
+				}
+				if creq.Fragment {
+					sws.fragment[id] = true
+				}
+				sws.mu.Unlock()
+			}
+			wr := &pb.WatchResponse{
+				Header:   sws.newResponseHeader(wsrev),
+				WatchId:  int64(id),
+				Created:  true,
+				Canceled: err != nil,
+			}
+			if err != nil {
+				wr.CancelReason = err.Error()
+			}
+			select {
+			case sws.ctrlStream <- wr:
+			case <-sws.closec:
+				return nil
+			}
+
+		case *pb.WatchRequest_CancelRequest:
+			if uv.CancelRequest != nil {
+				id := uv.CancelRequest.WatchId
+				err := sws.watchStream.Cancel(mvcc.WatchID(id))
+				if err == nil {
+					sws.ctrlStream <- &pb.WatchResponse{
+						Header:   sws.newResponseHeader(sws.watchStream.Rev()),
+						WatchId:  id,
+						Canceled: true,
+					}
+					sws.mu.Lock()
+					delete(sws.progress, mvcc.WatchID(id))
+					delete(sws.prevKV, mvcc.WatchID(id))
+					delete(sws.fragment, mvcc.WatchID(id))
+					sws.mu.Unlock()
+				}
+			}
+		case *pb.WatchRequest_ProgressRequest:
+			if uv.ProgressRequest != nil {
+				sws.ctrlStream <- &pb.WatchResponse{
+					Header:  sws.newResponseHeader(sws.watchStream.Rev()),
+					WatchId: -1, // response is not associated with any WatchId and will be broadcast to all watch channels
+				}
+			}
+		default:
+			// we probably should not shutdown the entire stream when
+			// receive an valid command.
+			// so just do nothing instead.
+			continue
+		}
+	}
+}
+
+func (sws *serverWatchStream) sendLoop() {
+	// watch ids that are currently active
+	ids := make(map[mvcc.WatchID]struct{})
+	// watch responses pending on a watch id creation message
+	pending := make(map[mvcc.WatchID][]*pb.WatchResponse)
+
+	interval := GetProgressReportInterval()
+	progressTicker := time.NewTicker(interval)
+
+	defer func() {
+		progressTicker.Stop()
+		// drain the chan to clean up pending events
+		for ws := range sws.watchStream.Chan() {
+			mvcc.ReportEventReceived(len(ws.Events))
+		}
+		for _, wrs := range pending {
+			for _, ws := range wrs {
+				mvcc.ReportEventReceived(len(ws.Events))
+			}
+		}
+	}()
+
+	for {
+		select {
+		case wresp, ok := <-sws.watchStream.Chan():
+			if !ok {
+				return
+			}
+
+			// TODO: evs is []mvccpb.Event type
+			// either return []*mvccpb.Event from the mvcc package
+			// or define protocol buffer with []mvccpb.Event.
+			evs := wresp.Events
+			events := make([]*mvccpb.Event, len(evs))
+			sws.mu.RLock()
+			needPrevKV := sws.prevKV[wresp.WatchID]
+			sws.mu.RUnlock()
+			for i := range evs {
+				events[i] = &evs[i]
+				if needPrevKV {
+					opt := mvcc.RangeOptions{Rev: evs[i].Kv.ModRevision - 1}
+					r, err := sws.watchable.Range(evs[i].Kv.Key, nil, opt)
+					if err == nil && len(r.KVs) != 0 {
+						events[i].PrevKv = &(r.KVs[0])
+					}
+				}
+			}
+
+			canceled := wresp.CompactRevision != 0
+			wr := &pb.WatchResponse{
+				Header:          sws.newResponseHeader(wresp.Revision),
+				WatchId:         int64(wresp.WatchID),
+				Events:          events,
+				CompactRevision: wresp.CompactRevision,
+				Canceled:        canceled,
+			}
+
+			if _, okID := ids[wresp.WatchID]; !okID {
+				// buffer if id not yet announced
+				wrs := append(pending[wresp.WatchID], wr)
+				pending[wresp.WatchID] = wrs
+				continue
+			}
+
+			mvcc.ReportEventReceived(len(evs))
+
+			sws.mu.RLock()
+			fragmented, ok := sws.fragment[wresp.WatchID]
+			sws.mu.RUnlock()
+
+			var serr error
+			if !fragmented && !ok {
+				serr = sws.gRPCStream.Send(wr)
+			} else {
+				serr = sendFragments(wr, sws.maxRequestBytes, sws.gRPCStream.Send)
+			}
+
+			if serr != nil {
+				if isClientCtxErr(sws.gRPCStream.Context().Err(), serr) {
+					if sws.lg != nil {
+						sws.lg.Debug("failed to send watch response to gRPC stream", zap.Error(serr))
+					} else {
+						plog.Debugf("failed to send watch response to gRPC stream (%q)", serr.Error())
+					}
+				} else {
+					if sws.lg != nil {
+						sws.lg.Warn("failed to send watch response to gRPC stream", zap.Error(serr))
+					} else {
+						plog.Warningf("failed to send watch response to gRPC stream (%q)", serr.Error())
+					}
+					streamFailures.WithLabelValues("send", "watch").Inc()
+				}
+				return
+			}
+
+			sws.mu.Lock()
+			if len(evs) > 0 && sws.progress[wresp.WatchID] {
+				// elide next progress update if sent a key update
+				sws.progress[wresp.WatchID] = false
+			}
+			sws.mu.Unlock()
+
+		case c, ok := <-sws.ctrlStream:
+			if !ok {
+				return
+			}
+
+			if err := sws.gRPCStream.Send(c); err != nil {
+				if isClientCtxErr(sws.gRPCStream.Context().Err(), err) {
+					if sws.lg != nil {
+						sws.lg.Debug("failed to send watch control response to gRPC stream", zap.Error(err))
+					} else {
+						plog.Debugf("failed to send watch control response to gRPC stream (%q)", err.Error())
+					}
+				} else {
+					if sws.lg != nil {
+						sws.lg.Warn("failed to send watch control response to gRPC stream", zap.Error(err))
+					} else {
+						plog.Warningf("failed to send watch control response to gRPC stream (%q)", err.Error())
+					}
+					streamFailures.WithLabelValues("send", "watch").Inc()
+				}
+				return
+			}
+
+			// track id creation
+			wid := mvcc.WatchID(c.WatchId)
+			if c.Canceled {
+				delete(ids, wid)
+				continue
+			}
+			if c.Created {
+				// flush buffered events
+				ids[wid] = struct{}{}
+				for _, v := range pending[wid] {
+					mvcc.ReportEventReceived(len(v.Events))
+					if err := sws.gRPCStream.Send(v); err != nil {
+						if isClientCtxErr(sws.gRPCStream.Context().Err(), err) {
+							if sws.lg != nil {
+								sws.lg.Debug("failed to send pending watch response to gRPC stream", zap.Error(err))
+							} else {
+								plog.Debugf("failed to send pending watch response to gRPC stream (%q)", err.Error())
+							}
+						} else {
+							if sws.lg != nil {
+								sws.lg.Warn("failed to send pending watch response to gRPC stream", zap.Error(err))
+							} else {
+								plog.Warningf("failed to send pending watch response to gRPC stream (%q)", err.Error())
+							}
+							streamFailures.WithLabelValues("send", "watch").Inc()
+						}
+						return
+					}
+				}
+				delete(pending, wid)
+			}
+
+		case <-progressTicker.C:
+			sws.mu.Lock()
+			for id, ok := range sws.progress {
+				if ok {
+					sws.watchStream.RequestProgress(id)
+				}
+				sws.progress[id] = true
+			}
+			sws.mu.Unlock()
+
+		case <-sws.closec:
+			return
+		}
+	}
+}
+
+func sendFragments(
+	wr *pb.WatchResponse,
+	maxRequestBytes int,
+	sendFunc func(*pb.WatchResponse) error) error {
+	// no need to fragment if total request size is smaller
+	// than max request limit or response contains only one event
+	if wr.Size() < maxRequestBytes || len(wr.Events) < 2 {
+		return sendFunc(wr)
+	}
+
+	ow := *wr
+	ow.Events = make([]*mvccpb.Event, 0)
+	ow.Fragment = true
+
+	var idx int
+	for {
+		cur := ow
+		for _, ev := range wr.Events[idx:] {
+			cur.Events = append(cur.Events, ev)
+			if len(cur.Events) > 1 && cur.Size() >= maxRequestBytes {
+				cur.Events = cur.Events[:len(cur.Events)-1]
+				break
+			}
+			idx++
+		}
+		if idx == len(wr.Events) {
+			// last response has no more fragment
+			cur.Fragment = false
+		}
+		if err := sendFunc(&cur); err != nil {
+			return err
+		}
+		if !cur.Fragment {
+			break
+		}
+	}
+	return nil
+}
+
+func (sws *serverWatchStream) close() {
+	sws.watchStream.Close()
+	close(sws.closec)
+	sws.wg.Wait()
+}
+
+func (sws *serverWatchStream) newResponseHeader(rev int64) *pb.ResponseHeader {
+	return &pb.ResponseHeader{
+		ClusterId: uint64(sws.clusterID),
+		MemberId:  uint64(sws.memberID),
+		Revision:  rev,
+		RaftTerm:  sws.sg.Term(),
+	}
+}
+
+func filterNoDelete(e mvccpb.Event) bool {
+	return e.Type == mvccpb.DELETE
+}
+
+func filterNoPut(e mvccpb.Event) bool {
+	return e.Type == mvccpb.PUT
+}
+
+// FiltersFromRequest returns "mvcc.FilterFunc" from a given watch create request.
+func FiltersFromRequest(creq *pb.WatchCreateRequest) []mvcc.FilterFunc {
+	filters := make([]mvcc.FilterFunc, 0, len(creq.Filters))
+	for _, ft := range creq.Filters {
+		switch ft {
+		case pb.WatchCreateRequest_NOPUT:
+			filters = append(filters, filterNoPut)
+		case pb.WatchCreateRequest_NODELETE:
+			filters = append(filters, filterNoDelete)
+		default:
+		}
+	}
+	return filters
+}