diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/db.go b/vendor/go.etcd.io/etcd/etcdserver/api/snap/db.go
new file mode 100644
index 0000000..3002ccd
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/db.go
@@ -0,0 +1,104 @@
+// 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 snap
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"time"
+
+	"go.etcd.io/etcd/pkg/fileutil"
+
+	humanize "github.com/dustin/go-humanize"
+	"go.uber.org/zap"
+)
+
+var ErrNoDBSnapshot = errors.New("snap: snapshot file doesn't exist")
+
+// SaveDBFrom saves snapshot of the database from the given reader. It
+// guarantees the save operation is atomic.
+func (s *Snapshotter) SaveDBFrom(r io.Reader, id uint64) (int64, error) {
+	start := time.Now()
+
+	f, err := ioutil.TempFile(s.dir, "tmp")
+	if err != nil {
+		return 0, err
+	}
+	var n int64
+	n, err = io.Copy(f, r)
+	if err == nil {
+		fsyncStart := time.Now()
+		err = fileutil.Fsync(f)
+		snapDBFsyncSec.Observe(time.Since(fsyncStart).Seconds())
+	}
+	f.Close()
+	if err != nil {
+		os.Remove(f.Name())
+		return n, err
+	}
+	fn := s.dbFilePath(id)
+	if fileutil.Exist(fn) {
+		os.Remove(f.Name())
+		return n, nil
+	}
+	err = os.Rename(f.Name(), fn)
+	if err != nil {
+		os.Remove(f.Name())
+		return n, err
+	}
+
+	if s.lg != nil {
+		s.lg.Info(
+			"saved database snapshot to disk",
+			zap.String("path", fn),
+			zap.Int64("bytes", n),
+			zap.String("size", humanize.Bytes(uint64(n))),
+		)
+	} else {
+		plog.Infof("saved database snapshot to disk [total bytes: %d]", n)
+	}
+
+	snapDBSaveSec.Observe(time.Since(start).Seconds())
+	return n, nil
+}
+
+// DBFilePath returns the file path for the snapshot of the database with
+// given id. If the snapshot does not exist, it returns error.
+func (s *Snapshotter) DBFilePath(id uint64) (string, error) {
+	if _, err := fileutil.ReadDir(s.dir); err != nil {
+		return "", err
+	}
+	fn := s.dbFilePath(id)
+	if fileutil.Exist(fn) {
+		return fn, nil
+	}
+	if s.lg != nil {
+		s.lg.Warn(
+			"failed to find [SNAPSHOT-INDEX].snap.db",
+			zap.Uint64("snapshot-index", id),
+			zap.String("snapshot-file-path", fn),
+			zap.Error(ErrNoDBSnapshot),
+		)
+	}
+	return "", ErrNoDBSnapshot
+}
+
+func (s *Snapshotter) dbFilePath(id uint64) string {
+	return filepath.Join(s.dir, fmt.Sprintf("%016x.snap.db", id))
+}
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/doc.go b/vendor/go.etcd.io/etcd/etcdserver/api/snap/doc.go
new file mode 100644
index 0000000..dcc5db5
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/doc.go
@@ -0,0 +1,17 @@
+// 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 snap handles Raft nodes' states with snapshots.
+// The snapshot logic is internal to etcd server and raft package.
+package snap
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/message.go b/vendor/go.etcd.io/etcd/etcdserver/api/snap/message.go
new file mode 100644
index 0000000..c1151e2
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/message.go
@@ -0,0 +1,64 @@
+// 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 snap
+
+import (
+	"io"
+
+	"go.etcd.io/etcd/pkg/ioutil"
+	"go.etcd.io/etcd/raft/raftpb"
+)
+
+// Message is a struct that contains a raft Message and a ReadCloser. The type
+// of raft message MUST be MsgSnap, which contains the raft meta-data and an
+// additional data []byte field that contains the snapshot of the actual state
+// machine.
+// Message contains the ReadCloser field for handling large snapshot. This avoid
+// copying the entire snapshot into a byte array, which consumes a lot of memory.
+//
+// User of Message should close the Message after sending it.
+type Message struct {
+	raftpb.Message
+	ReadCloser io.ReadCloser
+	TotalSize  int64
+	closeC     chan bool
+}
+
+func NewMessage(rs raftpb.Message, rc io.ReadCloser, rcSize int64) *Message {
+	return &Message{
+		Message:    rs,
+		ReadCloser: ioutil.NewExactReadCloser(rc, rcSize),
+		TotalSize:  int64(rs.Size()) + rcSize,
+		closeC:     make(chan bool, 1),
+	}
+}
+
+// CloseNotify returns a channel that receives a single value
+// when the message sent is finished. true indicates the sent
+// is successful.
+func (m Message) CloseNotify() <-chan bool {
+	return m.closeC
+}
+
+func (m Message) CloseWithError(err error) {
+	if cerr := m.ReadCloser.Close(); cerr != nil {
+		err = cerr
+	}
+	if err == nil {
+		m.closeC <- true
+	} else {
+		m.closeC <- false
+	}
+}
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/metrics.go b/vendor/go.etcd.io/etcd/etcdserver/api/snap/metrics.go
new file mode 100644
index 0000000..2affecf
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/metrics.go
@@ -0,0 +1,82 @@
+// 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 snap
+
+import "github.com/prometheus/client_golang/prometheus"
+
+var (
+	snapMarshallingSec = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd_debugging",
+		Subsystem: "snap",
+		Name:      "save_marshalling_duration_seconds",
+		Help:      "The marshalling cost distributions of save called by snapshot.",
+
+		// lowest bucket start of upper bound 0.001 sec (1 ms) with factor 2
+		// highest bucket start of 0.001 sec * 2^13 == 8.192 sec
+		Buckets: prometheus.ExponentialBuckets(0.001, 2, 14),
+	})
+
+	snapSaveSec = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd_debugging",
+		Subsystem: "snap",
+		Name:      "save_total_duration_seconds",
+		Help:      "The total latency distributions of save called by snapshot.",
+
+		// lowest bucket start of upper bound 0.001 sec (1 ms) with factor 2
+		// highest bucket start of 0.001 sec * 2^13 == 8.192 sec
+		Buckets: prometheus.ExponentialBuckets(0.001, 2, 14),
+	})
+
+	snapFsyncSec = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd",
+		Subsystem: "snap",
+		Name:      "fsync_duration_seconds",
+		Help:      "The latency distributions of fsync called by snap.",
+
+		// lowest bucket start of upper bound 0.001 sec (1 ms) with factor 2
+		// highest bucket start of 0.001 sec * 2^13 == 8.192 sec
+		Buckets: prometheus.ExponentialBuckets(0.001, 2, 14),
+	})
+
+	snapDBSaveSec = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd",
+		Subsystem: "snap_db",
+		Name:      "save_total_duration_seconds",
+		Help:      "The total latency distributions of v3 snapshot save",
+
+		// lowest bucket start of upper bound 0.1 sec (100 ms) with factor 2
+		// highest bucket start of 0.1 sec * 2^9 == 51.2 sec
+		Buckets: prometheus.ExponentialBuckets(0.1, 2, 10),
+	})
+
+	snapDBFsyncSec = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd",
+		Subsystem: "snap_db",
+		Name:      "fsync_duration_seconds",
+		Help:      "The latency distributions of fsyncing .snap.db file",
+
+		// lowest bucket start of upper bound 0.001 sec (1 ms) with factor 2
+		// highest bucket start of 0.001 sec * 2^13 == 8.192 sec
+		Buckets: prometheus.ExponentialBuckets(0.001, 2, 14),
+	})
+)
+
+func init() {
+	prometheus.MustRegister(snapMarshallingSec)
+	prometheus.MustRegister(snapSaveSec)
+	prometheus.MustRegister(snapFsyncSec)
+	prometheus.MustRegister(snapDBSaveSec)
+	prometheus.MustRegister(snapDBFsyncSec)
+}
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/snappb/snap.pb.go b/vendor/go.etcd.io/etcd/etcdserver/api/snap/snappb/snap.pb.go
new file mode 100644
index 0000000..e72b577
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/snappb/snap.pb.go
@@ -0,0 +1,336 @@
+// Code generated by protoc-gen-gogo. DO NOT EDIT.
+// source: snap.proto
+
+/*
+	Package snappb is a generated protocol buffer package.
+
+	It is generated from these files:
+		snap.proto
+
+	It has these top-level messages:
+		Snapshot
+*/
+package snappb
+
+import (
+	"fmt"
+
+	proto "github.com/golang/protobuf/proto"
+
+	math "math"
+
+	_ "github.com/gogo/protobuf/gogoproto"
+
+	io "io"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type Snapshot struct {
+	Crc              uint32 `protobuf:"varint,1,opt,name=crc" json:"crc"`
+	Data             []byte `protobuf:"bytes,2,opt,name=data" json:"data,omitempty"`
+	XXX_unrecognized []byte `json:"-"`
+}
+
+func (m *Snapshot) Reset()                    { *m = Snapshot{} }
+func (m *Snapshot) String() string            { return proto.CompactTextString(m) }
+func (*Snapshot) ProtoMessage()               {}
+func (*Snapshot) Descriptor() ([]byte, []int) { return fileDescriptorSnap, []int{0} }
+
+func init() {
+	proto.RegisterType((*Snapshot)(nil), "snappb.snapshot")
+}
+func (m *Snapshot) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *Snapshot) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	dAtA[i] = 0x8
+	i++
+	i = encodeVarintSnap(dAtA, i, uint64(m.Crc))
+	if m.Data != nil {
+		dAtA[i] = 0x12
+		i++
+		i = encodeVarintSnap(dAtA, i, uint64(len(m.Data)))
+		i += copy(dAtA[i:], m.Data)
+	}
+	if m.XXX_unrecognized != nil {
+		i += copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	return i, nil
+}
+
+func encodeVarintSnap(dAtA []byte, offset int, v uint64) int {
+	for v >= 1<<7 {
+		dAtA[offset] = uint8(v&0x7f | 0x80)
+		v >>= 7
+		offset++
+	}
+	dAtA[offset] = uint8(v)
+	return offset + 1
+}
+func (m *Snapshot) Size() (n int) {
+	var l int
+	_ = l
+	n += 1 + sovSnap(uint64(m.Crc))
+	if m.Data != nil {
+		l = len(m.Data)
+		n += 1 + l + sovSnap(uint64(l))
+	}
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
+func sovSnap(x uint64) (n int) {
+	for {
+		n++
+		x >>= 7
+		if x == 0 {
+			break
+		}
+	}
+	return n
+}
+func sozSnap(x uint64) (n int) {
+	return sovSnap(uint64((x << 1) ^ uint64((int64(x) >> 63))))
+}
+func (m *Snapshot) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowSnap
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: snapshot: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: snapshot: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Crc", wireType)
+			}
+			m.Crc = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowSnap
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Crc |= (uint32(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Data", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowSnap
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthSnap
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Data = append(m.Data[:0], dAtA[iNdEx:postIndex]...)
+			if m.Data == nil {
+				m.Data = []byte{}
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipSnap(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthSnap
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.XXX_unrecognized = append(m.XXX_unrecognized, dAtA[iNdEx:iNdEx+skippy]...)
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func skipSnap(dAtA []byte) (n int, err error) {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return 0, ErrIntOverflowSnap
+			}
+			if iNdEx >= l {
+				return 0, io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		wireType := int(wire & 0x7)
+		switch wireType {
+		case 0:
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowSnap
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				iNdEx++
+				if dAtA[iNdEx-1] < 0x80 {
+					break
+				}
+			}
+			return iNdEx, nil
+		case 1:
+			iNdEx += 8
+			return iNdEx, nil
+		case 2:
+			var length int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowSnap
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				length |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			iNdEx += length
+			if length < 0 {
+				return 0, ErrInvalidLengthSnap
+			}
+			return iNdEx, nil
+		case 3:
+			for {
+				var innerWire uint64
+				var start int = iNdEx
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return 0, ErrIntOverflowSnap
+					}
+					if iNdEx >= l {
+						return 0, io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					innerWire |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				innerWireType := int(innerWire & 0x7)
+				if innerWireType == 4 {
+					break
+				}
+				next, err := skipSnap(dAtA[start:])
+				if err != nil {
+					return 0, err
+				}
+				iNdEx = start + next
+			}
+			return iNdEx, nil
+		case 4:
+			return iNdEx, nil
+		case 5:
+			iNdEx += 4
+			return iNdEx, nil
+		default:
+			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
+		}
+	}
+	panic("unreachable")
+}
+
+var (
+	ErrInvalidLengthSnap = fmt.Errorf("proto: negative length found during unmarshaling")
+	ErrIntOverflowSnap   = fmt.Errorf("proto: integer overflow")
+)
+
+func init() { proto.RegisterFile("snap.proto", fileDescriptorSnap) }
+
+var fileDescriptorSnap = []byte{
+	// 126 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0xe2, 0x2a, 0xce, 0x4b, 0x2c,
+	0xd0, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0x62, 0x03, 0xb1, 0x0b, 0x92, 0xa4, 0x44, 0xd2, 0xf3,
+	0xd3, 0xf3, 0xc1, 0x42, 0xfa, 0x20, 0x16, 0x44, 0x56, 0xc9, 0x8c, 0x8b, 0x03, 0x24, 0x5f, 0x9c,
+	0x91, 0x5f, 0x22, 0x24, 0xc6, 0xc5, 0x9c, 0x5c, 0x94, 0x2c, 0xc1, 0xa8, 0xc0, 0xa8, 0xc1, 0xeb,
+	0xc4, 0x72, 0xe2, 0x9e, 0x3c, 0x43, 0x10, 0x48, 0x40, 0x48, 0x88, 0x8b, 0x25, 0x25, 0xb1, 0x24,
+	0x51, 0x82, 0x49, 0x81, 0x51, 0x83, 0x27, 0x08, 0xcc, 0x76, 0x12, 0x39, 0xf1, 0x50, 0x8e, 0xe1,
+	0xc4, 0x23, 0x39, 0xc6, 0x0b, 0x8f, 0xe4, 0x18, 0x1f, 0x3c, 0x92, 0x63, 0x9c, 0xf1, 0x58, 0x8e,
+	0x01, 0x10, 0x00, 0x00, 0xff, 0xff, 0xd8, 0x0f, 0x32, 0xb2, 0x78, 0x00, 0x00, 0x00,
+}
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/snappb/snap.proto b/vendor/go.etcd.io/etcd/etcdserver/api/snap/snappb/snap.proto
new file mode 100644
index 0000000..cd3d21d
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/snappb/snap.proto
@@ -0,0 +1,14 @@
+syntax = "proto2";
+package snappb;
+
+import "gogoproto/gogo.proto";
+
+option (gogoproto.marshaler_all) = true;
+option (gogoproto.sizer_all) = true;
+option (gogoproto.unmarshaler_all) = true;
+option (gogoproto.goproto_getters_all) = false;
+
+message snapshot {
+	optional uint32 crc  = 1 [(gogoproto.nullable) = false];
+	optional bytes data  = 2;
+}
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/snap/snapshotter.go b/vendor/go.etcd.io/etcd/etcdserver/api/snap/snapshotter.go
new file mode 100644
index 0000000..7e79333
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/snap/snapshotter.go
@@ -0,0 +1,255 @@
+// 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 snap
+
+import (
+	"errors"
+	"fmt"
+	"hash/crc32"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"go.etcd.io/etcd/etcdserver/api/snap/snappb"
+	pioutil "go.etcd.io/etcd/pkg/ioutil"
+	"go.etcd.io/etcd/pkg/pbutil"
+	"go.etcd.io/etcd/raft"
+	"go.etcd.io/etcd/raft/raftpb"
+
+	"github.com/coreos/pkg/capnslog"
+	"go.uber.org/zap"
+)
+
+const snapSuffix = ".snap"
+
+var (
+	plog = capnslog.NewPackageLogger("go.etcd.io/etcd/v3", "snap")
+
+	ErrNoSnapshot    = errors.New("snap: no available snapshot")
+	ErrEmptySnapshot = errors.New("snap: empty snapshot")
+	ErrCRCMismatch   = errors.New("snap: crc mismatch")
+	crcTable         = crc32.MakeTable(crc32.Castagnoli)
+
+	// A map of valid files that can be present in the snap folder.
+	validFiles = map[string]bool{
+		"db": true,
+	}
+)
+
+type Snapshotter struct {
+	lg  *zap.Logger
+	dir string
+}
+
+func New(lg *zap.Logger, dir string) *Snapshotter {
+	return &Snapshotter{
+		lg:  lg,
+		dir: dir,
+	}
+}
+
+func (s *Snapshotter) SaveSnap(snapshot raftpb.Snapshot) error {
+	if raft.IsEmptySnap(snapshot) {
+		return nil
+	}
+	return s.save(&snapshot)
+}
+
+func (s *Snapshotter) save(snapshot *raftpb.Snapshot) error {
+	start := time.Now()
+
+	fname := fmt.Sprintf("%016x-%016x%s", snapshot.Metadata.Term, snapshot.Metadata.Index, snapSuffix)
+	b := pbutil.MustMarshal(snapshot)
+	crc := crc32.Update(0, crcTable, b)
+	snap := snappb.Snapshot{Crc: crc, Data: b}
+	d, err := snap.Marshal()
+	if err != nil {
+		return err
+	}
+	snapMarshallingSec.Observe(time.Since(start).Seconds())
+
+	spath := filepath.Join(s.dir, fname)
+
+	fsyncStart := time.Now()
+	err = pioutil.WriteAndSyncFile(spath, d, 0666)
+	snapFsyncSec.Observe(time.Since(fsyncStart).Seconds())
+
+	if err != nil {
+		if s.lg != nil {
+			s.lg.Warn("failed to write a snap file", zap.String("path", spath), zap.Error(err))
+		}
+		rerr := os.Remove(spath)
+		if rerr != nil {
+			if s.lg != nil {
+				s.lg.Warn("failed to remove a broken snap file", zap.String("path", spath), zap.Error(err))
+			} else {
+				plog.Errorf("failed to remove broken snapshot file %s", spath)
+			}
+		}
+		return err
+	}
+
+	snapSaveSec.Observe(time.Since(start).Seconds())
+	return nil
+}
+
+func (s *Snapshotter) Load() (*raftpb.Snapshot, error) {
+	names, err := s.snapNames()
+	if err != nil {
+		return nil, err
+	}
+	var snap *raftpb.Snapshot
+	for _, name := range names {
+		if snap, err = loadSnap(s.lg, s.dir, name); err == nil {
+			break
+		}
+	}
+	if err != nil {
+		return nil, ErrNoSnapshot
+	}
+	return snap, nil
+}
+
+func loadSnap(lg *zap.Logger, dir, name string) (*raftpb.Snapshot, error) {
+	fpath := filepath.Join(dir, name)
+	snap, err := Read(lg, fpath)
+	if err != nil {
+		brokenPath := fpath + ".broken"
+		if lg != nil {
+			lg.Warn("failed to read a snap file", zap.String("path", fpath), zap.Error(err))
+		}
+		if rerr := os.Rename(fpath, brokenPath); rerr != nil {
+			if lg != nil {
+				lg.Warn("failed to rename a broken snap file", zap.String("path", fpath), zap.String("broken-path", brokenPath), zap.Error(rerr))
+			} else {
+				plog.Warningf("cannot rename broken snapshot file %v to %v: %v", fpath, brokenPath, rerr)
+			}
+		} else {
+			if lg != nil {
+				lg.Warn("renamed to a broken snap file", zap.String("path", fpath), zap.String("broken-path", brokenPath))
+			}
+		}
+	}
+	return snap, err
+}
+
+// Read reads the snapshot named by snapname and returns the snapshot.
+func Read(lg *zap.Logger, snapname string) (*raftpb.Snapshot, error) {
+	b, err := ioutil.ReadFile(snapname)
+	if err != nil {
+		if lg != nil {
+			lg.Warn("failed to read a snap file", zap.String("path", snapname), zap.Error(err))
+		} else {
+			plog.Errorf("cannot read file %v: %v", snapname, err)
+		}
+		return nil, err
+	}
+
+	if len(b) == 0 {
+		if lg != nil {
+			lg.Warn("failed to read empty snapshot file", zap.String("path", snapname))
+		} else {
+			plog.Errorf("unexpected empty snapshot")
+		}
+		return nil, ErrEmptySnapshot
+	}
+
+	var serializedSnap snappb.Snapshot
+	if err = serializedSnap.Unmarshal(b); err != nil {
+		if lg != nil {
+			lg.Warn("failed to unmarshal snappb.Snapshot", zap.String("path", snapname), zap.Error(err))
+		} else {
+			plog.Errorf("corrupted snapshot file %v: %v", snapname, err)
+		}
+		return nil, err
+	}
+
+	if len(serializedSnap.Data) == 0 || serializedSnap.Crc == 0 {
+		if lg != nil {
+			lg.Warn("failed to read empty snapshot data", zap.String("path", snapname))
+		} else {
+			plog.Errorf("unexpected empty snapshot")
+		}
+		return nil, ErrEmptySnapshot
+	}
+
+	crc := crc32.Update(0, crcTable, serializedSnap.Data)
+	if crc != serializedSnap.Crc {
+		if lg != nil {
+			lg.Warn("snap file is corrupt",
+				zap.String("path", snapname),
+				zap.Uint32("prev-crc", serializedSnap.Crc),
+				zap.Uint32("new-crc", crc),
+			)
+		} else {
+			plog.Errorf("corrupted snapshot file %v: crc mismatch", snapname)
+		}
+		return nil, ErrCRCMismatch
+	}
+
+	var snap raftpb.Snapshot
+	if err = snap.Unmarshal(serializedSnap.Data); err != nil {
+		if lg != nil {
+			lg.Warn("failed to unmarshal raftpb.Snapshot", zap.String("path", snapname), zap.Error(err))
+		} else {
+			plog.Errorf("corrupted snapshot file %v: %v", snapname, err)
+		}
+		return nil, err
+	}
+	return &snap, nil
+}
+
+// snapNames returns the filename of the snapshots in logical time order (from newest to oldest).
+// If there is no available snapshots, an ErrNoSnapshot will be returned.
+func (s *Snapshotter) snapNames() ([]string, error) {
+	dir, err := os.Open(s.dir)
+	if err != nil {
+		return nil, err
+	}
+	defer dir.Close()
+	names, err := dir.Readdirnames(-1)
+	if err != nil {
+		return nil, err
+	}
+	snaps := checkSuffix(s.lg, names)
+	if len(snaps) == 0 {
+		return nil, ErrNoSnapshot
+	}
+	sort.Sort(sort.Reverse(sort.StringSlice(snaps)))
+	return snaps, nil
+}
+
+func checkSuffix(lg *zap.Logger, names []string) []string {
+	snaps := []string{}
+	for i := range names {
+		if strings.HasSuffix(names[i], snapSuffix) {
+			snaps = append(snaps, names[i])
+		} else {
+			// If we find a file which is not a snapshot then check if it's
+			// a vaild file. If not throw out a warning.
+			if _, ok := validFiles[names[i]]; !ok {
+				if lg != nil {
+					lg.Warn("found unexpected non-snap file; skipping", zap.String("path", names[i]))
+				} else {
+					plog.Warningf("skipped unexpected non snapshot file %v", names[i])
+				}
+			}
+		}
+	}
+	return snaps
+}