diff --git a/vendor/github.com/coreos/etcd/rafthttp/stream.go b/vendor/github.com/coreos/etcd/rafthttp/stream.go
new file mode 100644
index 0000000..af49c18
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/rafthttp/stream.go
@@ -0,0 +1,533 @@
+// 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 rafthttp
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"path"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/time/rate"
+
+	"github.com/coreos/etcd/etcdserver/stats"
+	"github.com/coreos/etcd/pkg/httputil"
+	"github.com/coreos/etcd/pkg/transport"
+	"github.com/coreos/etcd/pkg/types"
+	"github.com/coreos/etcd/raft/raftpb"
+	"github.com/coreos/etcd/version"
+	"github.com/coreos/go-semver/semver"
+)
+
+const (
+	streamTypeMessage  streamType = "message"
+	streamTypeMsgAppV2 streamType = "msgappv2"
+
+	streamBufSize = 4096
+)
+
+var (
+	errUnsupportedStreamType = fmt.Errorf("unsupported stream type")
+
+	// the key is in string format "major.minor.patch"
+	supportedStream = map[string][]streamType{
+		"2.0.0": {},
+		"2.1.0": {streamTypeMsgAppV2, streamTypeMessage},
+		"2.2.0": {streamTypeMsgAppV2, streamTypeMessage},
+		"2.3.0": {streamTypeMsgAppV2, streamTypeMessage},
+		"3.0.0": {streamTypeMsgAppV2, streamTypeMessage},
+		"3.1.0": {streamTypeMsgAppV2, streamTypeMessage},
+		"3.2.0": {streamTypeMsgAppV2, streamTypeMessage},
+		"3.3.0": {streamTypeMsgAppV2, streamTypeMessage},
+	}
+)
+
+type streamType string
+
+func (t streamType) endpoint() string {
+	switch t {
+	case streamTypeMsgAppV2:
+		return path.Join(RaftStreamPrefix, "msgapp")
+	case streamTypeMessage:
+		return path.Join(RaftStreamPrefix, "message")
+	default:
+		plog.Panicf("unhandled stream type %v", t)
+		return ""
+	}
+}
+
+func (t streamType) String() string {
+	switch t {
+	case streamTypeMsgAppV2:
+		return "stream MsgApp v2"
+	case streamTypeMessage:
+		return "stream Message"
+	default:
+		return "unknown stream"
+	}
+}
+
+var (
+	// linkHeartbeatMessage is a special message used as heartbeat message in
+	// link layer. It never conflicts with messages from raft because raft
+	// doesn't send out messages without From and To fields.
+	linkHeartbeatMessage = raftpb.Message{Type: raftpb.MsgHeartbeat}
+)
+
+func isLinkHeartbeatMessage(m *raftpb.Message) bool {
+	return m.Type == raftpb.MsgHeartbeat && m.From == 0 && m.To == 0
+}
+
+type outgoingConn struct {
+	t streamType
+	io.Writer
+	http.Flusher
+	io.Closer
+}
+
+// streamWriter writes messages to the attached outgoingConn.
+type streamWriter struct {
+	peerID types.ID
+	status *peerStatus
+	fs     *stats.FollowerStats
+	r      Raft
+
+	mu      sync.Mutex // guard field working and closer
+	closer  io.Closer
+	working bool
+
+	msgc  chan raftpb.Message
+	connc chan *outgoingConn
+	stopc chan struct{}
+	done  chan struct{}
+}
+
+// startStreamWriter creates a streamWrite and starts a long running go-routine that accepts
+// messages and writes to the attached outgoing connection.
+func startStreamWriter(id types.ID, status *peerStatus, fs *stats.FollowerStats, r Raft) *streamWriter {
+	w := &streamWriter{
+		peerID: id,
+		status: status,
+		fs:     fs,
+		r:      r,
+		msgc:   make(chan raftpb.Message, streamBufSize),
+		connc:  make(chan *outgoingConn),
+		stopc:  make(chan struct{}),
+		done:   make(chan struct{}),
+	}
+	go w.run()
+	return w
+}
+
+func (cw *streamWriter) run() {
+	var (
+		msgc       chan raftpb.Message
+		heartbeatc <-chan time.Time
+		t          streamType
+		enc        encoder
+		flusher    http.Flusher
+		batched    int
+	)
+	tickc := time.NewTicker(ConnReadTimeout / 3)
+	defer tickc.Stop()
+	unflushed := 0
+
+	plog.Infof("started streaming with peer %s (writer)", cw.peerID)
+
+	for {
+		select {
+		case <-heartbeatc:
+			err := enc.encode(&linkHeartbeatMessage)
+			unflushed += linkHeartbeatMessage.Size()
+			if err == nil {
+				flusher.Flush()
+				batched = 0
+				sentBytes.WithLabelValues(cw.peerID.String()).Add(float64(unflushed))
+				unflushed = 0
+				continue
+			}
+
+			cw.status.deactivate(failureType{source: t.String(), action: "heartbeat"}, err.Error())
+
+			sentFailures.WithLabelValues(cw.peerID.String()).Inc()
+			cw.close()
+			plog.Warningf("lost the TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
+			heartbeatc, msgc = nil, nil
+
+		case m := <-msgc:
+			err := enc.encode(&m)
+			if err == nil {
+				unflushed += m.Size()
+
+				if len(msgc) == 0 || batched > streamBufSize/2 {
+					flusher.Flush()
+					sentBytes.WithLabelValues(cw.peerID.String()).Add(float64(unflushed))
+					unflushed = 0
+					batched = 0
+				} else {
+					batched++
+				}
+
+				continue
+			}
+
+			cw.status.deactivate(failureType{source: t.String(), action: "write"}, err.Error())
+			cw.close()
+			plog.Warningf("lost the TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
+			heartbeatc, msgc = nil, nil
+			cw.r.ReportUnreachable(m.To)
+			sentFailures.WithLabelValues(cw.peerID.String()).Inc()
+
+		case conn := <-cw.connc:
+			cw.mu.Lock()
+			closed := cw.closeUnlocked()
+			t = conn.t
+			switch conn.t {
+			case streamTypeMsgAppV2:
+				enc = newMsgAppV2Encoder(conn.Writer, cw.fs)
+			case streamTypeMessage:
+				enc = &messageEncoder{w: conn.Writer}
+			default:
+				plog.Panicf("unhandled stream type %s", conn.t)
+			}
+			flusher = conn.Flusher
+			unflushed = 0
+			cw.status.activate()
+			cw.closer = conn.Closer
+			cw.working = true
+			cw.mu.Unlock()
+
+			if closed {
+				plog.Warningf("closed an existing TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
+			}
+			plog.Infof("established a TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
+			heartbeatc, msgc = tickc.C, cw.msgc
+		case <-cw.stopc:
+			if cw.close() {
+				plog.Infof("closed the TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
+			}
+			plog.Infof("stopped streaming with peer %s (writer)", cw.peerID)
+			close(cw.done)
+			return
+		}
+	}
+}
+
+func (cw *streamWriter) writec() (chan<- raftpb.Message, bool) {
+	cw.mu.Lock()
+	defer cw.mu.Unlock()
+	return cw.msgc, cw.working
+}
+
+func (cw *streamWriter) close() bool {
+	cw.mu.Lock()
+	defer cw.mu.Unlock()
+	return cw.closeUnlocked()
+}
+
+func (cw *streamWriter) closeUnlocked() bool {
+	if !cw.working {
+		return false
+	}
+	if err := cw.closer.Close(); err != nil {
+		plog.Errorf("peer %s (writer) connection close error: %v", cw.peerID, err)
+	}
+	if len(cw.msgc) > 0 {
+		cw.r.ReportUnreachable(uint64(cw.peerID))
+	}
+	cw.msgc = make(chan raftpb.Message, streamBufSize)
+	cw.working = false
+	return true
+}
+
+func (cw *streamWriter) attach(conn *outgoingConn) bool {
+	select {
+	case cw.connc <- conn:
+		return true
+	case <-cw.done:
+		return false
+	}
+}
+
+func (cw *streamWriter) stop() {
+	close(cw.stopc)
+	<-cw.done
+}
+
+// streamReader is a long-running go-routine that dials to the remote stream
+// endpoint and reads messages from the response body returned.
+type streamReader struct {
+	peerID types.ID
+	typ    streamType
+
+	tr     *Transport
+	picker *urlPicker
+	status *peerStatus
+	recvc  chan<- raftpb.Message
+	propc  chan<- raftpb.Message
+
+	rl *rate.Limiter // alters the frequency of dial retrial attempts
+
+	errorc chan<- error
+
+	mu     sync.Mutex
+	paused bool
+	closer io.Closer
+
+	ctx    context.Context
+	cancel context.CancelFunc
+	done   chan struct{}
+}
+
+func (cr *streamReader) start() {
+	cr.done = make(chan struct{})
+	if cr.errorc == nil {
+		cr.errorc = cr.tr.ErrorC
+	}
+	if cr.ctx == nil {
+		cr.ctx, cr.cancel = context.WithCancel(context.Background())
+	}
+	go cr.run()
+}
+
+func (cr *streamReader) run() {
+	t := cr.typ
+	plog.Infof("started streaming with peer %s (%s reader)", cr.peerID, t)
+	for {
+		rc, err := cr.dial(t)
+		if err != nil {
+			if err != errUnsupportedStreamType {
+				cr.status.deactivate(failureType{source: t.String(), action: "dial"}, err.Error())
+			}
+		} else {
+			cr.status.activate()
+			plog.Infof("established a TCP streaming connection with peer %s (%s reader)", cr.peerID, cr.typ)
+			err = cr.decodeLoop(rc, t)
+			plog.Warningf("lost the TCP streaming connection with peer %s (%s reader)", cr.peerID, cr.typ)
+			switch {
+			// all data is read out
+			case err == io.EOF:
+			// connection is closed by the remote
+			case transport.IsClosedConnError(err):
+			default:
+				cr.status.deactivate(failureType{source: t.String(), action: "read"}, err.Error())
+			}
+		}
+		// Wait for a while before new dial attempt
+		err = cr.rl.Wait(cr.ctx)
+		if cr.ctx.Err() != nil {
+			plog.Infof("stopped streaming with peer %s (%s reader)", cr.peerID, t)
+			close(cr.done)
+			return
+		}
+		if err != nil {
+			plog.Errorf("streaming with peer %s (%s reader) rate limiter error: %v", cr.peerID, t, err)
+		}
+	}
+}
+
+func (cr *streamReader) decodeLoop(rc io.ReadCloser, t streamType) error {
+	var dec decoder
+	cr.mu.Lock()
+	switch t {
+	case streamTypeMsgAppV2:
+		dec = newMsgAppV2Decoder(rc, cr.tr.ID, cr.peerID)
+	case streamTypeMessage:
+		dec = &messageDecoder{r: rc}
+	default:
+		plog.Panicf("unhandled stream type %s", t)
+	}
+	select {
+	case <-cr.ctx.Done():
+		cr.mu.Unlock()
+		if err := rc.Close(); err != nil {
+			return err
+		}
+		return io.EOF
+	default:
+		cr.closer = rc
+	}
+	cr.mu.Unlock()
+
+	for {
+		m, err := dec.decode()
+		if err != nil {
+			cr.mu.Lock()
+			cr.close()
+			cr.mu.Unlock()
+			return err
+		}
+
+		receivedBytes.WithLabelValues(types.ID(m.From).String()).Add(float64(m.Size()))
+
+		cr.mu.Lock()
+		paused := cr.paused
+		cr.mu.Unlock()
+
+		if paused {
+			continue
+		}
+
+		if isLinkHeartbeatMessage(&m) {
+			// raft is not interested in link layer
+			// heartbeat message, so we should ignore
+			// it.
+			continue
+		}
+
+		recvc := cr.recvc
+		if m.Type == raftpb.MsgProp {
+			recvc = cr.propc
+		}
+
+		select {
+		case recvc <- m:
+		default:
+			if cr.status.isActive() {
+				plog.MergeWarningf("dropped internal raft message from %s since receiving buffer is full (overloaded network)", types.ID(m.From))
+			}
+			plog.Debugf("dropped %s from %s since receiving buffer is full", m.Type, types.ID(m.From))
+			recvFailures.WithLabelValues(types.ID(m.From).String()).Inc()
+		}
+	}
+}
+
+func (cr *streamReader) stop() {
+	cr.mu.Lock()
+	cr.cancel()
+	cr.close()
+	cr.mu.Unlock()
+	<-cr.done
+}
+
+func (cr *streamReader) dial(t streamType) (io.ReadCloser, error) {
+	u := cr.picker.pick()
+	uu := u
+	uu.Path = path.Join(t.endpoint(), cr.tr.ID.String())
+
+	req, err := http.NewRequest("GET", uu.String(), nil)
+	if err != nil {
+		cr.picker.unreachable(u)
+		return nil, fmt.Errorf("failed to make http request to %v (%v)", u, err)
+	}
+	req.Header.Set("X-Server-From", cr.tr.ID.String())
+	req.Header.Set("X-Server-Version", version.Version)
+	req.Header.Set("X-Min-Cluster-Version", version.MinClusterVersion)
+	req.Header.Set("X-Etcd-Cluster-ID", cr.tr.ClusterID.String())
+	req.Header.Set("X-Raft-To", cr.peerID.String())
+
+	setPeerURLsHeader(req, cr.tr.URLs)
+
+	req = req.WithContext(cr.ctx)
+
+	cr.mu.Lock()
+	select {
+	case <-cr.ctx.Done():
+		cr.mu.Unlock()
+		return nil, fmt.Errorf("stream reader is stopped")
+	default:
+	}
+	cr.mu.Unlock()
+
+	resp, err := cr.tr.streamRt.RoundTrip(req)
+	if err != nil {
+		cr.picker.unreachable(u)
+		return nil, err
+	}
+
+	rv := serverVersion(resp.Header)
+	lv := semver.Must(semver.NewVersion(version.Version))
+	if compareMajorMinorVersion(rv, lv) == -1 && !checkStreamSupport(rv, t) {
+		httputil.GracefulClose(resp)
+		cr.picker.unreachable(u)
+		return nil, errUnsupportedStreamType
+	}
+
+	switch resp.StatusCode {
+	case http.StatusGone:
+		httputil.GracefulClose(resp)
+		cr.picker.unreachable(u)
+		reportCriticalError(errMemberRemoved, cr.errorc)
+		return nil, errMemberRemoved
+	case http.StatusOK:
+		return resp.Body, nil
+	case http.StatusNotFound:
+		httputil.GracefulClose(resp)
+		cr.picker.unreachable(u)
+		return nil, fmt.Errorf("peer %s failed to find local node %s", cr.peerID, cr.tr.ID)
+	case http.StatusPreconditionFailed:
+		b, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			cr.picker.unreachable(u)
+			return nil, err
+		}
+		httputil.GracefulClose(resp)
+		cr.picker.unreachable(u)
+
+		switch strings.TrimSuffix(string(b), "\n") {
+		case errIncompatibleVersion.Error():
+			plog.Errorf("request sent was ignored by peer %s (server version incompatible)", cr.peerID)
+			return nil, errIncompatibleVersion
+		case errClusterIDMismatch.Error():
+			plog.Errorf("request sent was ignored (cluster ID mismatch: peer[%s]=%s, local=%s)",
+				cr.peerID, resp.Header.Get("X-Etcd-Cluster-ID"), cr.tr.ClusterID)
+			return nil, errClusterIDMismatch
+		default:
+			return nil, fmt.Errorf("unhandled error %q when precondition failed", string(b))
+		}
+	default:
+		httputil.GracefulClose(resp)
+		cr.picker.unreachable(u)
+		return nil, fmt.Errorf("unhandled http status %d", resp.StatusCode)
+	}
+}
+
+func (cr *streamReader) close() {
+	if cr.closer != nil {
+		if err := cr.closer.Close(); err != nil {
+			plog.Errorf("peer %s (reader) connection close error: %v", cr.peerID, err)
+		}
+	}
+	cr.closer = nil
+}
+
+func (cr *streamReader) pause() {
+	cr.mu.Lock()
+	defer cr.mu.Unlock()
+	cr.paused = true
+}
+
+func (cr *streamReader) resume() {
+	cr.mu.Lock()
+	defer cr.mu.Unlock()
+	cr.paused = false
+}
+
+// checkStreamSupport checks whether the stream type is supported in the
+// given version.
+func checkStreamSupport(v *semver.Version, t streamType) bool {
+	nv := &semver.Version{Major: v.Major, Minor: v.Minor}
+	for _, s := range supportedStream[nv.String()] {
+		if s == t {
+			return true
+		}
+	}
+	return false
+}