diff --git a/vendor/go.etcd.io/etcd/raft/raftpb/confchange.go b/vendor/go.etcd.io/etcd/raft/raftpb/confchange.go
new file mode 100644
index 0000000..46a7a70
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/raftpb/confchange.go
@@ -0,0 +1,170 @@
+// Copyright 2019 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 raftpb
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/gogo/protobuf/proto"
+)
+
+// ConfChangeI abstracts over ConfChangeV2 and (legacy) ConfChange to allow
+// treating them in a unified manner.
+type ConfChangeI interface {
+	AsV2() ConfChangeV2
+	AsV1() (ConfChange, bool)
+}
+
+// MarshalConfChange calls Marshal on the underlying ConfChange or ConfChangeV2
+// and returns the result along with the corresponding EntryType.
+func MarshalConfChange(c ConfChangeI) (EntryType, []byte, error) {
+	var typ EntryType
+	var ccdata []byte
+	var err error
+	if ccv1, ok := c.AsV1(); ok {
+		typ = EntryConfChange
+		ccdata, err = ccv1.Marshal()
+	} else {
+		ccv2 := c.AsV2()
+		typ = EntryConfChangeV2
+		ccdata, err = ccv2.Marshal()
+	}
+	return typ, ccdata, err
+}
+
+// AsV2 returns a V2 configuration change carrying out the same operation.
+func (c ConfChange) AsV2() ConfChangeV2 {
+	return ConfChangeV2{
+		Changes: []ConfChangeSingle{{
+			Type:   c.Type,
+			NodeID: c.NodeID,
+		}},
+		Context: c.Context,
+	}
+}
+
+// AsV1 returns the ConfChange and true.
+func (c ConfChange) AsV1() (ConfChange, bool) {
+	return c, true
+}
+
+// AsV2 is the identity.
+func (c ConfChangeV2) AsV2() ConfChangeV2 { return c }
+
+// AsV1 returns ConfChange{} and false.
+func (c ConfChangeV2) AsV1() (ConfChange, bool) { return ConfChange{}, false }
+
+// EnterJoint returns two bools. The second bool is true if and only if this
+// config change will use Joint Consensus, which is the case if it contains more
+// than one change or if the use of Joint Consensus was requested explicitly.
+// The first bool can only be true if second one is, and indicates whether the
+// Joint State will be left automatically.
+func (c *ConfChangeV2) EnterJoint() (autoLeave bool, ok bool) {
+	// NB: in theory, more config changes could qualify for the "simple"
+	// protocol but it depends on the config on top of which the changes apply.
+	// For example, adding two learners is not OK if both nodes are part of the
+	// base config (i.e. two voters are turned into learners in the process of
+	// applying the conf change). In practice, these distinctions should not
+	// matter, so we keep it simple and use Joint Consensus liberally.
+	if c.Transition != ConfChangeTransitionAuto || len(c.Changes) > 1 {
+		// Use Joint Consensus.
+		var autoLeave bool
+		switch c.Transition {
+		case ConfChangeTransitionAuto:
+			autoLeave = true
+		case ConfChangeTransitionJointImplicit:
+			autoLeave = true
+		case ConfChangeTransitionJointExplicit:
+		default:
+			panic(fmt.Sprintf("unknown transition: %+v", c))
+		}
+		return autoLeave, true
+	}
+	return false, false
+}
+
+// LeaveJoint is true if the configuration change leaves a joint configuration.
+// This is the case if the ConfChangeV2 is zero, with the possible exception of
+// the Context field.
+func (c *ConfChangeV2) LeaveJoint() bool {
+	cpy := *c
+	cpy.Context = nil
+	return proto.Equal(&cpy, &ConfChangeV2{})
+}
+
+// ConfChangesFromString parses a Space-delimited sequence of operations into a
+// slice of ConfChangeSingle. The supported operations are:
+// - vn: make n a voter,
+// - ln: make n a learner,
+// - rn: remove n, and
+// - un: update n.
+func ConfChangesFromString(s string) ([]ConfChangeSingle, error) {
+	var ccs []ConfChangeSingle
+	toks := strings.Split(strings.TrimSpace(s), " ")
+	if toks[0] == "" {
+		toks = nil
+	}
+	for _, tok := range toks {
+		if len(tok) < 2 {
+			return nil, fmt.Errorf("unknown token %s", tok)
+		}
+		var cc ConfChangeSingle
+		switch tok[0] {
+		case 'v':
+			cc.Type = ConfChangeAddNode
+		case 'l':
+			cc.Type = ConfChangeAddLearnerNode
+		case 'r':
+			cc.Type = ConfChangeRemoveNode
+		case 'u':
+			cc.Type = ConfChangeUpdateNode
+		default:
+			return nil, fmt.Errorf("unknown input: %s", tok)
+		}
+		id, err := strconv.ParseUint(tok[1:], 10, 64)
+		if err != nil {
+			return nil, err
+		}
+		cc.NodeID = id
+		ccs = append(ccs, cc)
+	}
+	return ccs, nil
+}
+
+// ConfChangesToString is the inverse to ConfChangesFromString.
+func ConfChangesToString(ccs []ConfChangeSingle) string {
+	var buf strings.Builder
+	for i, cc := range ccs {
+		if i > 0 {
+			buf.WriteByte(' ')
+		}
+		switch cc.Type {
+		case ConfChangeAddNode:
+			buf.WriteByte('v')
+		case ConfChangeAddLearnerNode:
+			buf.WriteByte('l')
+		case ConfChangeRemoveNode:
+			buf.WriteByte('r')
+		case ConfChangeUpdateNode:
+			buf.WriteByte('u')
+		default:
+			buf.WriteString("unknown")
+		}
+		fmt.Fprintf(&buf, "%d", cc.NodeID)
+	}
+	return buf.String()
+}