diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go b/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
index c39702e..d02a7ee 100644
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/balancer.go
@@ -12,24 +12,45 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package balancer implements client balancer.
 package balancer
 
 import (
-	"fmt"
 	"strconv"
 	"sync"
 	"time"
 
+	"go.etcd.io/etcd/clientv3/balancer/connectivity"
 	"go.etcd.io/etcd/clientv3/balancer/picker"
 
 	"go.uber.org/zap"
 	"google.golang.org/grpc/balancer"
-	"google.golang.org/grpc/connectivity"
+	grpcconnectivity "google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/resolver"
 	_ "google.golang.org/grpc/resolver/dns"         // register DNS resolver
 	_ "google.golang.org/grpc/resolver/passthrough" // register passthrough resolver
 )
 
+// Config defines balancer configurations.
+type Config struct {
+	// Policy configures balancer policy.
+	Policy picker.Policy
+
+	// Picker implements gRPC picker.
+	// Leave empty if "Policy" field is not custom.
+	// TODO: currently custom policy is not supported.
+	// Picker picker.Picker
+
+	// Name defines an additional name for balancer.
+	// Useful for balancer testing to avoid register conflicts.
+	// If empty, defaults to policy name.
+	Name string
+
+	// Logger configures balancer logging.
+	// If nil, logs are discarded.
+	Logger *zap.Logger
+}
+
 // RegisterBuilder creates and registers a builder. Since this function calls balancer.Register, it
 // must be invoked at initialization time.
 func RegisterBuilder(cfg Config) {
@@ -59,16 +80,13 @@
 
 		addrToSc: make(map[resolver.Address]balancer.SubConn),
 		scToAddr: make(map[balancer.SubConn]resolver.Address),
-		scToSt:   make(map[balancer.SubConn]connectivity.State),
+		scToSt:   make(map[balancer.SubConn]grpcconnectivity.State),
 
-		currentConn: nil,
-		csEvltr:     &connectivityStateEvaluator{},
+		currentConn:          nil,
+		connectivityRecorder: connectivity.New(b.cfg.Logger),
 
 		// initialize picker always returns "ErrNoSubConnAvailable"
-		Picker: picker.NewErr(balancer.ErrNoSubConnAvailable),
-	}
-	if bb.lg == nil {
-		bb.lg = zap.NewNop()
+		picker: picker.NewErr(balancer.ErrNoSubConnAvailable),
 	}
 
 	// TODO: support multiple connections
@@ -112,13 +130,12 @@
 
 	addrToSc map[resolver.Address]balancer.SubConn
 	scToAddr map[balancer.SubConn]resolver.Address
-	scToSt   map[balancer.SubConn]connectivity.State
+	scToSt   map[balancer.SubConn]grpcconnectivity.State
 
-	currentConn  balancer.ClientConn
-	currentState connectivity.State
-	csEvltr      *connectivityStateEvaluator
+	currentConn          balancer.ClientConn
+	connectivityRecorder connectivity.Recorder
 
-	picker.Picker
+	picker picker.Picker
 }
 
 // HandleResolvedAddrs implements "grpc/balancer.Balancer" interface.
@@ -128,7 +145,11 @@
 		bb.lg.Warn("HandleResolvedAddrs called with error", zap.String("balancer-id", bb.id), zap.Error(err))
 		return
 	}
-	bb.lg.Info("resolved", zap.String("balancer-id", bb.id), zap.Strings("addresses", addrsToStrings(addrs)))
+	bb.lg.Info("resolved",
+		zap.String("picker", bb.picker.String()),
+		zap.String("balancer-id", bb.id),
+		zap.Strings("addresses", addrsToStrings(addrs)),
+	)
 
 	bb.mu.Lock()
 	defer bb.mu.Unlock()
@@ -139,12 +160,13 @@
 		if _, ok := bb.addrToSc[addr]; !ok {
 			sc, err := bb.currentConn.NewSubConn([]resolver.Address{addr}, balancer.NewSubConnOptions{})
 			if err != nil {
-				bb.lg.Warn("NewSubConn failed", zap.String("balancer-id", bb.id), zap.Error(err), zap.String("address", addr.Addr))
+				bb.lg.Warn("NewSubConn failed", zap.String("picker", bb.picker.String()), zap.String("balancer-id", bb.id), zap.Error(err), zap.String("address", addr.Addr))
 				continue
 			}
+			bb.lg.Info("created subconn", zap.String("address", addr.Addr))
 			bb.addrToSc[addr] = sc
 			bb.scToAddr[sc] = addr
-			bb.scToSt[sc] = connectivity.Idle
+			bb.scToSt[sc] = grpcconnectivity.Idle
 			sc.Connect()
 		}
 	}
@@ -157,6 +179,7 @@
 
 			bb.lg.Info(
 				"removed subconn",
+				zap.String("picker", bb.picker.String()),
 				zap.String("balancer-id", bb.id),
 				zap.String("address", addr.Addr),
 				zap.String("subconn", scToString(sc)),
@@ -171,7 +194,7 @@
 }
 
 // HandleSubConnStateChange implements "grpc/balancer.Balancer" interface.
-func (bb *baseBalancer) HandleSubConnStateChange(sc balancer.SubConn, s connectivity.State) {
+func (bb *baseBalancer) HandleSubConnStateChange(sc balancer.SubConn, s grpcconnectivity.State) {
 	bb.mu.Lock()
 	defer bb.mu.Unlock()
 
@@ -179,8 +202,10 @@
 	if !ok {
 		bb.lg.Warn(
 			"state change for an unknown subconn",
+			zap.String("picker", bb.picker.String()),
 			zap.String("balancer-id", bb.id),
 			zap.String("subconn", scToString(sc)),
+			zap.Int("subconn-size", len(bb.scToAddr)),
 			zap.String("state", s.String()),
 		)
 		return
@@ -188,9 +213,11 @@
 
 	bb.lg.Info(
 		"state changed",
+		zap.String("picker", bb.picker.String()),
 		zap.String("balancer-id", bb.id),
-		zap.Bool("connected", s == connectivity.Ready),
+		zap.Bool("connected", s == grpcconnectivity.Ready),
 		zap.String("subconn", scToString(sc)),
+		zap.Int("subconn-size", len(bb.scToAddr)),
 		zap.String("address", bb.scToAddr[sc].Addr),
 		zap.String("old-state", old.String()),
 		zap.String("new-state", s.String()),
@@ -198,68 +225,63 @@
 
 	bb.scToSt[sc] = s
 	switch s {
-	case connectivity.Idle:
+	case grpcconnectivity.Idle:
 		sc.Connect()
-	case connectivity.Shutdown:
+	case grpcconnectivity.Shutdown:
 		// When an address was removed by resolver, b called RemoveSubConn but
 		// kept the sc's state in scToSt. Remove state for this sc here.
 		delete(bb.scToAddr, sc)
 		delete(bb.scToSt, sc)
 	}
 
-	oldAggrState := bb.currentState
-	bb.currentState = bb.csEvltr.recordTransition(old, s)
+	oldAggrState := bb.connectivityRecorder.GetCurrentState()
+	bb.connectivityRecorder.RecordTransition(old, s)
 
-	// Regenerate picker when one of the following happens:
+	// Update balancer picker when one of the following happens:
 	//  - this sc became ready from not-ready
 	//  - this sc became not-ready from ready
 	//  - the aggregated state of balancer became TransientFailure from non-TransientFailure
 	//  - the aggregated state of balancer became non-TransientFailure from TransientFailure
-	if (s == connectivity.Ready) != (old == connectivity.Ready) ||
-		(bb.currentState == connectivity.TransientFailure) != (oldAggrState == connectivity.TransientFailure) {
-		bb.regeneratePicker()
+	if (s == grpcconnectivity.Ready) != (old == grpcconnectivity.Ready) ||
+		(bb.connectivityRecorder.GetCurrentState() == grpcconnectivity.TransientFailure) != (oldAggrState == grpcconnectivity.TransientFailure) {
+		bb.updatePicker()
 	}
 
-	bb.currentConn.UpdateBalancerState(bb.currentState, bb.Picker)
+	bb.currentConn.UpdateBalancerState(bb.connectivityRecorder.GetCurrentState(), bb.picker)
 }
 
-func (bb *baseBalancer) regeneratePicker() {
-	if bb.currentState == connectivity.TransientFailure {
+func (bb *baseBalancer) updatePicker() {
+	if bb.connectivityRecorder.GetCurrentState() == grpcconnectivity.TransientFailure {
+		bb.picker = picker.NewErr(balancer.ErrTransientFailure)
 		bb.lg.Info(
-			"generated transient error picker",
+			"updated picker to transient error picker",
+			zap.String("picker", bb.picker.String()),
 			zap.String("balancer-id", bb.id),
 			zap.String("policy", bb.policy.String()),
 		)
-		bb.Picker = picker.NewErr(balancer.ErrTransientFailure)
 		return
 	}
 
 	// only pass ready subconns to picker
-	scs := make([]balancer.SubConn, 0)
-	addrToSc := make(map[resolver.Address]balancer.SubConn)
 	scToAddr := make(map[balancer.SubConn]resolver.Address)
 	for addr, sc := range bb.addrToSc {
-		if st, ok := bb.scToSt[sc]; ok && st == connectivity.Ready {
-			scs = append(scs, sc)
-			addrToSc[addr] = sc
+		if st, ok := bb.scToSt[sc]; ok && st == grpcconnectivity.Ready {
 			scToAddr[sc] = addr
 		}
 	}
 
-	switch bb.policy {
-	case picker.RoundrobinBalanced:
-		bb.Picker = picker.NewRoundrobinBalanced(bb.lg, scs, addrToSc, scToAddr)
-
-	default:
-		panic(fmt.Errorf("invalid balancer picker policy (%d)", bb.policy))
-	}
-
+	bb.picker = picker.New(picker.Config{
+		Policy:                   bb.policy,
+		Logger:                   bb.lg,
+		SubConnToResolverAddress: scToAddr,
+	})
 	bb.lg.Info(
-		"generated picker",
+		"updated picker",
+		zap.String("picker", bb.picker.String()),
 		zap.String("balancer-id", bb.id),
 		zap.String("policy", bb.policy.String()),
-		zap.Strings("subconn-ready", scsToStrings(addrToSc)),
-		zap.Int("subconn-size", len(addrToSc)),
+		zap.Strings("subconn-ready", scsToStrings(scToAddr)),
+		zap.Int("subconn-size", len(scToAddr)),
 	)
 }
 
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/config.go b/vendor/go.etcd.io/etcd/clientv3/balancer/config.go
deleted file mode 100644
index 0339a84..0000000
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/config.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2018 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 balancer
-
-import (
-	"go.etcd.io/etcd/clientv3/balancer/picker"
-
-	"go.uber.org/zap"
-)
-
-// Config defines balancer configurations.
-type Config struct {
-	// Policy configures balancer policy.
-	Policy picker.Policy
-
-	// Name defines an additional name for balancer.
-	// Useful for balancer testing to avoid register conflicts.
-	// If empty, defaults to policy name.
-	Name string
-
-	// Logger configures balancer logging.
-	// If nil, logs are discarded.
-	Logger *zap.Logger
-}
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity.go b/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity.go
deleted file mode 100644
index 6cdeb3f..0000000
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity.go
+++ /dev/null
@@ -1,58 +0,0 @@
-// Copyright 2018 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 balancer
-
-import "google.golang.org/grpc/connectivity"
-
-// connectivityStateEvaluator gets updated by addrConns when their
-// states transition, based on which it evaluates the state of
-// ClientConn.
-type connectivityStateEvaluator struct {
-	numReady            uint64 // Number of addrConns in ready state.
-	numConnecting       uint64 // Number of addrConns in connecting state.
-	numTransientFailure uint64 // Number of addrConns in transientFailure.
-}
-
-// recordTransition records state change happening in every subConn and based on
-// that it evaluates what aggregated state should be.
-// It can only transition between Ready, Connecting and TransientFailure. Other states,
-// Idle and Shutdown are transitioned into by ClientConn; in the beginning of the connection
-// before any subConn is created ClientConn is in idle state. In the end when ClientConn
-// closes it is in Shutdown state.
-//
-// recordTransition should only be called synchronously from the same goroutine.
-func (cse *connectivityStateEvaluator) recordTransition(oldState, newState connectivity.State) connectivity.State {
-	// Update counters.
-	for idx, state := range []connectivity.State{oldState, newState} {
-		updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
-		switch state {
-		case connectivity.Ready:
-			cse.numReady += updateVal
-		case connectivity.Connecting:
-			cse.numConnecting += updateVal
-		case connectivity.TransientFailure:
-			cse.numTransientFailure += updateVal
-		}
-	}
-
-	// Evaluate.
-	if cse.numReady > 0 {
-		return connectivity.Ready
-	}
-	if cse.numConnecting > 0 {
-		return connectivity.Connecting
-	}
-	return connectivity.TransientFailure
-}
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity/connectivity.go b/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity/connectivity.go
new file mode 100644
index 0000000..4c4ad36
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/connectivity/connectivity.go
@@ -0,0 +1,93 @@
+// 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 connectivity implements client connectivity operations.
+package connectivity
+
+import (
+	"sync"
+
+	"go.uber.org/zap"
+	"google.golang.org/grpc/connectivity"
+)
+
+// Recorder records gRPC connectivity.
+type Recorder interface {
+	GetCurrentState() connectivity.State
+	RecordTransition(oldState, newState connectivity.State)
+}
+
+// New returns a new Recorder.
+func New(lg *zap.Logger) Recorder {
+	return &recorder{lg: lg}
+}
+
+// recorder takes the connectivity states of multiple SubConns
+// and returns one aggregated connectivity state.
+// ref. https://github.com/grpc/grpc-go/blob/master/balancer/balancer.go
+type recorder struct {
+	lg *zap.Logger
+
+	mu sync.RWMutex
+
+	cur connectivity.State
+
+	numReady            uint64 // Number of addrConns in ready state.
+	numConnecting       uint64 // Number of addrConns in connecting state.
+	numTransientFailure uint64 // Number of addrConns in transientFailure.
+}
+
+func (rc *recorder) GetCurrentState() (state connectivity.State) {
+	rc.mu.RLock()
+	defer rc.mu.RUnlock()
+	return rc.cur
+}
+
+// RecordTransition records state change happening in subConn and based on that
+// it evaluates what aggregated state should be.
+//
+//  - If at least one SubConn in Ready, the aggregated state is Ready;
+//  - Else if at least one SubConn in Connecting, the aggregated state is Connecting;
+//  - Else the aggregated state is TransientFailure.
+//
+// Idle and Shutdown are not considered.
+//
+// ref. https://github.com/grpc/grpc-go/blob/master/balancer/balancer.go
+func (rc *recorder) RecordTransition(oldState, newState connectivity.State) {
+	rc.mu.Lock()
+	defer rc.mu.Unlock()
+
+	for idx, state := range []connectivity.State{oldState, newState} {
+		updateVal := 2*uint64(idx) - 1 // -1 for oldState and +1 for new.
+		switch state {
+		case connectivity.Ready:
+			rc.numReady += updateVal
+		case connectivity.Connecting:
+			rc.numConnecting += updateVal
+		case connectivity.TransientFailure:
+			rc.numTransientFailure += updateVal
+		default:
+			rc.lg.Warn("connectivity recorder received unknown state", zap.String("connectivity-state", state.String()))
+		}
+	}
+
+	switch { // must be exclusive, no overlap
+	case rc.numReady > 0:
+		rc.cur = connectivity.Ready
+	case rc.numConnecting > 0:
+		rc.cur = connectivity.Connecting
+	default:
+		rc.cur = connectivity.TransientFailure
+	}
+}
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/doc.go b/vendor/go.etcd.io/etcd/clientv3/balancer/doc.go
deleted file mode 100644
index 45af5e9..0000000
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/doc.go
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright 2018 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 balancer implements client balancer.
-package balancer
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/grpc1.7-health.go b/vendor/go.etcd.io/etcd/clientv3/balancer/grpc1.7-health.go
deleted file mode 100644
index 2153767..0000000
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/grpc1.7-health.go
+++ /dev/null
@@ -1,657 +0,0 @@
-// Copyright 2018 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 balancer
-
-import (
-	"context"
-	"errors"
-	"io/ioutil"
-	"net/url"
-	"strings"
-	"sync"
-	"time"
-
-	"google.golang.org/grpc"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/grpclog"
-	healthpb "google.golang.org/grpc/health/grpc_health_v1"
-	"google.golang.org/grpc/status"
-)
-
-// TODO: replace with something better
-var lg = grpclog.NewLoggerV2(ioutil.Discard, ioutil.Discard, ioutil.Discard)
-
-const (
-	minHealthRetryDuration = 3 * time.Second
-	unknownService         = "unknown service grpc.health.v1.Health"
-)
-
-// ErrNoAddrAvailable is returned by Get() when the balancer does not have
-// any active connection to endpoints at the time.
-// This error is returned only when opts.BlockingWait is true.
-var ErrNoAddrAvailable = status.Error(codes.Unavailable, "there is no address available")
-
-type NotifyMsg int
-
-const (
-	NotifyReset NotifyMsg = iota
-	NotifyNext
-)
-
-// GRPC17Health does the bare minimum to expose multiple eps
-// to the grpc reconnection code path
-type GRPC17Health struct {
-	// addrs are the client's endpoint addresses for grpc
-	addrs []grpc.Address
-
-	// eps holds the raw endpoints from the client
-	eps []string
-
-	// notifyCh notifies grpc of the set of addresses for connecting
-	notifyCh chan []grpc.Address
-
-	// readyc closes once the first connection is up
-	readyc    chan struct{}
-	readyOnce sync.Once
-
-	// healthCheck checks an endpoint's health.
-	healthCheck        func(ep string) (bool, error)
-	healthCheckTimeout time.Duration
-
-	unhealthyMu        sync.RWMutex
-	unhealthyHostPorts map[string]time.Time
-
-	// mu protects all fields below.
-	mu sync.RWMutex
-
-	// upc closes when pinAddr transitions from empty to non-empty or the balancer closes.
-	upc chan struct{}
-
-	// downc closes when grpc calls down() on pinAddr
-	downc chan struct{}
-
-	// stopc is closed to signal updateNotifyLoop should stop.
-	stopc    chan struct{}
-	stopOnce sync.Once
-	wg       sync.WaitGroup
-
-	// donec closes when all goroutines are exited
-	donec chan struct{}
-
-	// updateAddrsC notifies updateNotifyLoop to update addrs.
-	updateAddrsC chan NotifyMsg
-
-	// grpc issues TLS cert checks using the string passed into dial so
-	// that string must be the host. To recover the full scheme://host URL,
-	// have a map from hosts to the original endpoint.
-	hostPort2ep map[string]string
-
-	// pinAddr is the currently pinned address; set to the empty string on
-	// initialization and shutdown.
-	pinAddr string
-
-	closed bool
-}
-
-// DialFunc defines gRPC dial function.
-type DialFunc func(ep string, dopts ...grpc.DialOption) (*grpc.ClientConn, error)
-
-// NewGRPC17Health returns a new health balancer with gRPC v1.7.
-func NewGRPC17Health(
-	eps []string,
-	timeout time.Duration,
-	dialFunc DialFunc,
-) *GRPC17Health {
-	notifyCh := make(chan []grpc.Address)
-	addrs := eps2addrs(eps)
-	hb := &GRPC17Health{
-		addrs:              addrs,
-		eps:                eps,
-		notifyCh:           notifyCh,
-		readyc:             make(chan struct{}),
-		healthCheck:        func(ep string) (bool, error) { return grpcHealthCheck(ep, dialFunc) },
-		unhealthyHostPorts: make(map[string]time.Time),
-		upc:                make(chan struct{}),
-		stopc:              make(chan struct{}),
-		downc:              make(chan struct{}),
-		donec:              make(chan struct{}),
-		updateAddrsC:       make(chan NotifyMsg),
-		hostPort2ep:        getHostPort2ep(eps),
-	}
-	if timeout < minHealthRetryDuration {
-		timeout = minHealthRetryDuration
-	}
-	hb.healthCheckTimeout = timeout
-
-	close(hb.downc)
-	go hb.updateNotifyLoop()
-	hb.wg.Add(1)
-	go func() {
-		defer hb.wg.Done()
-		hb.updateUnhealthy()
-	}()
-	return hb
-}
-
-func (b *GRPC17Health) Start(target string, config grpc.BalancerConfig) error { return nil }
-
-func (b *GRPC17Health) ConnectNotify() <-chan struct{} {
-	b.mu.Lock()
-	defer b.mu.Unlock()
-	return b.upc
-}
-
-func (b *GRPC17Health) UpdateAddrsC() chan NotifyMsg { return b.updateAddrsC }
-func (b *GRPC17Health) StopC() chan struct{}         { return b.stopc }
-
-func (b *GRPC17Health) Ready() <-chan struct{} { return b.readyc }
-
-func (b *GRPC17Health) Endpoint(hostPort string) string {
-	b.mu.RLock()
-	defer b.mu.RUnlock()
-	return b.hostPort2ep[hostPort]
-}
-
-func (b *GRPC17Health) Pinned() string {
-	b.mu.RLock()
-	defer b.mu.RUnlock()
-	return b.pinAddr
-}
-
-func (b *GRPC17Health) HostPortError(hostPort string, err error) {
-	if b.Endpoint(hostPort) == "" {
-		lg.Infof("clientv3/balancer: %q is stale (skip marking as unhealthy on %q)", hostPort, err.Error())
-		return
-	}
-
-	b.unhealthyMu.Lock()
-	b.unhealthyHostPorts[hostPort] = time.Now()
-	b.unhealthyMu.Unlock()
-	lg.Infof("clientv3/balancer: %q is marked unhealthy (%q)", hostPort, err.Error())
-}
-
-func (b *GRPC17Health) removeUnhealthy(hostPort, msg string) {
-	if b.Endpoint(hostPort) == "" {
-		lg.Infof("clientv3/balancer: %q was not in unhealthy (%q)", hostPort, msg)
-		return
-	}
-
-	b.unhealthyMu.Lock()
-	delete(b.unhealthyHostPorts, hostPort)
-	b.unhealthyMu.Unlock()
-	lg.Infof("clientv3/balancer: %q is removed from unhealthy (%q)", hostPort, msg)
-}
-
-func (b *GRPC17Health) countUnhealthy() (count int) {
-	b.unhealthyMu.RLock()
-	count = len(b.unhealthyHostPorts)
-	b.unhealthyMu.RUnlock()
-	return count
-}
-
-func (b *GRPC17Health) isUnhealthy(hostPort string) (unhealthy bool) {
-	b.unhealthyMu.RLock()
-	_, unhealthy = b.unhealthyHostPorts[hostPort]
-	b.unhealthyMu.RUnlock()
-	return unhealthy
-}
-
-func (b *GRPC17Health) cleanupUnhealthy() {
-	b.unhealthyMu.Lock()
-	for k, v := range b.unhealthyHostPorts {
-		if time.Since(v) > b.healthCheckTimeout {
-			delete(b.unhealthyHostPorts, k)
-			lg.Infof("clientv3/balancer: removed %q from unhealthy after %v", k, b.healthCheckTimeout)
-		}
-	}
-	b.unhealthyMu.Unlock()
-}
-
-func (b *GRPC17Health) liveAddrs() ([]grpc.Address, map[string]struct{}) {
-	unhealthyCnt := b.countUnhealthy()
-
-	b.mu.RLock()
-	defer b.mu.RUnlock()
-
-	hbAddrs := b.addrs
-	if len(b.addrs) == 1 || unhealthyCnt == 0 || unhealthyCnt == len(b.addrs) {
-		liveHostPorts := make(map[string]struct{}, len(b.hostPort2ep))
-		for k := range b.hostPort2ep {
-			liveHostPorts[k] = struct{}{}
-		}
-		return hbAddrs, liveHostPorts
-	}
-
-	addrs := make([]grpc.Address, 0, len(b.addrs)-unhealthyCnt)
-	liveHostPorts := make(map[string]struct{}, len(addrs))
-	for _, addr := range b.addrs {
-		if !b.isUnhealthy(addr.Addr) {
-			addrs = append(addrs, addr)
-			liveHostPorts[addr.Addr] = struct{}{}
-		}
-	}
-	return addrs, liveHostPorts
-}
-
-func (b *GRPC17Health) updateUnhealthy() {
-	for {
-		select {
-		case <-time.After(b.healthCheckTimeout):
-			b.cleanupUnhealthy()
-			pinned := b.Pinned()
-			if pinned == "" || b.isUnhealthy(pinned) {
-				select {
-				case b.updateAddrsC <- NotifyNext:
-				case <-b.stopc:
-					return
-				}
-			}
-		case <-b.stopc:
-			return
-		}
-	}
-}
-
-// NeedUpdate returns true if all connections are down or
-// addresses do not include current pinned address.
-func (b *GRPC17Health) NeedUpdate() bool {
-	// updating notifyCh can trigger new connections,
-	// need update addrs if all connections are down
-	// or addrs does not include pinAddr.
-	b.mu.RLock()
-	update := !hasAddr(b.addrs, b.pinAddr)
-	b.mu.RUnlock()
-	return update
-}
-
-func (b *GRPC17Health) UpdateAddrs(eps ...string) {
-	np := getHostPort2ep(eps)
-
-	b.mu.Lock()
-	defer b.mu.Unlock()
-
-	match := len(np) == len(b.hostPort2ep)
-	if match {
-		for k, v := range np {
-			if b.hostPort2ep[k] != v {
-				match = false
-				break
-			}
-		}
-	}
-	if match {
-		// same endpoints, so no need to update address
-		return
-	}
-
-	b.hostPort2ep = np
-	b.addrs, b.eps = eps2addrs(eps), eps
-
-	b.unhealthyMu.Lock()
-	b.unhealthyHostPorts = make(map[string]time.Time)
-	b.unhealthyMu.Unlock()
-}
-
-func (b *GRPC17Health) Next() {
-	b.mu.RLock()
-	downc := b.downc
-	b.mu.RUnlock()
-	select {
-	case b.updateAddrsC <- NotifyNext:
-	case <-b.stopc:
-	}
-	// wait until disconnect so new RPCs are not issued on old connection
-	select {
-	case <-downc:
-	case <-b.stopc:
-	}
-}
-
-func (b *GRPC17Health) updateNotifyLoop() {
-	defer close(b.donec)
-
-	for {
-		b.mu.RLock()
-		upc, downc, addr := b.upc, b.downc, b.pinAddr
-		b.mu.RUnlock()
-		// downc or upc should be closed
-		select {
-		case <-downc:
-			downc = nil
-		default:
-		}
-		select {
-		case <-upc:
-			upc = nil
-		default:
-		}
-		switch {
-		case downc == nil && upc == nil:
-			// stale
-			select {
-			case <-b.stopc:
-				return
-			default:
-			}
-		case downc == nil:
-			b.notifyAddrs(NotifyReset)
-			select {
-			case <-upc:
-			case msg := <-b.updateAddrsC:
-				b.notifyAddrs(msg)
-			case <-b.stopc:
-				return
-			}
-		case upc == nil:
-			select {
-			// close connections that are not the pinned address
-			case b.notifyCh <- []grpc.Address{{Addr: addr}}:
-			case <-downc:
-			case <-b.stopc:
-				return
-			}
-			select {
-			case <-downc:
-				b.notifyAddrs(NotifyReset)
-			case msg := <-b.updateAddrsC:
-				b.notifyAddrs(msg)
-			case <-b.stopc:
-				return
-			}
-		}
-	}
-}
-
-func (b *GRPC17Health) notifyAddrs(msg NotifyMsg) {
-	if msg == NotifyNext {
-		select {
-		case b.notifyCh <- []grpc.Address{}:
-		case <-b.stopc:
-			return
-		}
-	}
-	b.mu.RLock()
-	pinAddr := b.pinAddr
-	downc := b.downc
-	b.mu.RUnlock()
-	addrs, hostPorts := b.liveAddrs()
-
-	var waitDown bool
-	if pinAddr != "" {
-		_, ok := hostPorts[pinAddr]
-		waitDown = !ok
-	}
-
-	select {
-	case b.notifyCh <- addrs:
-		if waitDown {
-			select {
-			case <-downc:
-			case <-b.stopc:
-			}
-		}
-	case <-b.stopc:
-	}
-}
-
-func (b *GRPC17Health) Up(addr grpc.Address) func(error) {
-	if !b.mayPin(addr) {
-		return func(err error) {}
-	}
-
-	b.mu.Lock()
-	defer b.mu.Unlock()
-
-	// gRPC might call Up after it called Close. We add this check
-	// to "fix" it up at application layer. Otherwise, will panic
-	// if b.upc is already closed.
-	if b.closed {
-		return func(err error) {}
-	}
-
-	// gRPC might call Up on a stale address.
-	// Prevent updating pinAddr with a stale address.
-	if !hasAddr(b.addrs, addr.Addr) {
-		return func(err error) {}
-	}
-
-	if b.pinAddr != "" {
-		lg.Infof("clientv3/balancer: %q is up but not pinned (already pinned %q)", addr.Addr, b.pinAddr)
-		return func(err error) {}
-	}
-
-	// notify waiting Get()s and pin first connected address
-	close(b.upc)
-	b.downc = make(chan struct{})
-	b.pinAddr = addr.Addr
-	lg.Infof("clientv3/balancer: pin %q", addr.Addr)
-
-	// notify client that a connection is up
-	b.readyOnce.Do(func() { close(b.readyc) })
-
-	return func(err error) {
-		// If connected to a black hole endpoint or a killed server, the gRPC ping
-		// timeout will induce a network I/O error, and retrying until success;
-		// finding healthy endpoint on retry could take several timeouts and redials.
-		// To avoid wasting retries, gray-list unhealthy endpoints.
-		b.HostPortError(addr.Addr, err)
-
-		b.mu.Lock()
-		b.upc = make(chan struct{})
-		close(b.downc)
-		b.pinAddr = ""
-		b.mu.Unlock()
-		lg.Infof("clientv3/balancer: unpin %q (%q)", addr.Addr, err.Error())
-	}
-}
-
-func (b *GRPC17Health) mayPin(addr grpc.Address) bool {
-	if b.Endpoint(addr.Addr) == "" { // stale host:port
-		return false
-	}
-
-	b.unhealthyMu.RLock()
-	unhealthyCnt := len(b.unhealthyHostPorts)
-	failedTime, bad := b.unhealthyHostPorts[addr.Addr]
-	b.unhealthyMu.RUnlock()
-
-	b.mu.RLock()
-	skip := len(b.addrs) == 1 || unhealthyCnt == 0 || len(b.addrs) == unhealthyCnt
-	b.mu.RUnlock()
-	if skip || !bad {
-		return true
-	}
-
-	// prevent isolated member's endpoint from being infinitely retried, as follows:
-	//   1. keepalive pings detects GoAway with http2.ErrCodeEnhanceYourCalm
-	//   2. balancer 'Up' unpins with grpc: failed with network I/O error
-	//   3. grpc-healthcheck still SERVING, thus retry to pin
-	// instead, return before grpc-healthcheck if failed within healthcheck timeout
-	if elapsed := time.Since(failedTime); elapsed < b.healthCheckTimeout {
-		lg.Infof("clientv3/balancer: %q is up but not pinned (failed %v ago, require minimum %v after failure)", addr.Addr, elapsed, b.healthCheckTimeout)
-		return false
-	}
-
-	if ok, _ := b.healthCheck(addr.Addr); ok {
-		b.removeUnhealthy(addr.Addr, "health check success")
-		return true
-	}
-
-	b.HostPortError(addr.Addr, errors.New("health check failed"))
-	return false
-}
-
-func (b *GRPC17Health) Get(ctx context.Context, opts grpc.BalancerGetOptions) (grpc.Address, func(), error) {
-	var (
-		addr   string
-		closed bool
-	)
-
-	// If opts.BlockingWait is false (for fail-fast RPCs), it should return
-	// an address it has notified via Notify immediately instead of blocking.
-	if !opts.BlockingWait {
-		b.mu.RLock()
-		closed = b.closed
-		addr = b.pinAddr
-		b.mu.RUnlock()
-		if closed {
-			return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
-		}
-		if addr == "" {
-			return grpc.Address{Addr: ""}, nil, ErrNoAddrAvailable
-		}
-		return grpc.Address{Addr: addr}, func() {}, nil
-	}
-
-	for {
-		b.mu.RLock()
-		ch := b.upc
-		b.mu.RUnlock()
-		select {
-		case <-ch:
-		case <-b.donec:
-			return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
-		case <-ctx.Done():
-			return grpc.Address{Addr: ""}, nil, ctx.Err()
-		}
-		b.mu.RLock()
-		closed = b.closed
-		addr = b.pinAddr
-		b.mu.RUnlock()
-		// Close() which sets b.closed = true can be called before Get(), Get() must exit if balancer is closed.
-		if closed {
-			return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
-		}
-		if addr != "" {
-			break
-		}
-	}
-	return grpc.Address{Addr: addr}, func() {}, nil
-}
-
-func (b *GRPC17Health) Notify() <-chan []grpc.Address { return b.notifyCh }
-
-func (b *GRPC17Health) Close() error {
-	b.mu.Lock()
-	// In case gRPC calls close twice. TODO: remove the checking
-	// when we are sure that gRPC wont call close twice.
-	if b.closed {
-		b.mu.Unlock()
-		<-b.donec
-		return nil
-	}
-	b.closed = true
-	b.stopOnce.Do(func() { close(b.stopc) })
-	b.pinAddr = ""
-
-	// In the case of following scenario:
-	//	1. upc is not closed; no pinned address
-	// 	2. client issues an RPC, calling invoke(), which calls Get(), enters for loop, blocks
-	// 	3. client.conn.Close() calls balancer.Close(); closed = true
-	// 	4. for loop in Get() never exits since ctx is the context passed in by the client and may not be canceled
-	// we must close upc so Get() exits from blocking on upc
-	select {
-	case <-b.upc:
-	default:
-		// terminate all waiting Get()s
-		close(b.upc)
-	}
-
-	b.mu.Unlock()
-	b.wg.Wait()
-
-	// wait for updateNotifyLoop to finish
-	<-b.donec
-	close(b.notifyCh)
-
-	return nil
-}
-
-func grpcHealthCheck(ep string, dialFunc func(ep string, dopts ...grpc.DialOption) (*grpc.ClientConn, error)) (bool, error) {
-	conn, err := dialFunc(ep)
-	if err != nil {
-		return false, err
-	}
-	defer conn.Close()
-	cli := healthpb.NewHealthClient(conn)
-	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
-	resp, err := cli.Check(ctx, &healthpb.HealthCheckRequest{})
-	cancel()
-	if err != nil {
-		if s, ok := status.FromError(err); ok && s.Code() == codes.Unavailable {
-			if s.Message() == unknownService { // etcd < v3.3.0
-				return true, nil
-			}
-		}
-		return false, err
-	}
-	return resp.Status == healthpb.HealthCheckResponse_SERVING, nil
-}
-
-func hasAddr(addrs []grpc.Address, targetAddr string) bool {
-	for _, addr := range addrs {
-		if targetAddr == addr.Addr {
-			return true
-		}
-	}
-	return false
-}
-
-func getHost(ep string) string {
-	url, uerr := url.Parse(ep)
-	if uerr != nil || !strings.Contains(ep, "://") {
-		return ep
-	}
-	return url.Host
-}
-
-func eps2addrs(eps []string) []grpc.Address {
-	addrs := make([]grpc.Address, len(eps))
-	for i := range eps {
-		addrs[i].Addr = getHost(eps[i])
-	}
-	return addrs
-}
-
-func getHostPort2ep(eps []string) map[string]string {
-	hm := make(map[string]string, len(eps))
-	for i := range eps {
-		_, host, _ := parseEndpoint(eps[i])
-		hm[host] = eps[i]
-	}
-	return hm
-}
-
-func parseEndpoint(endpoint string) (proto string, host string, scheme string) {
-	proto = "tcp"
-	host = endpoint
-	url, uerr := url.Parse(endpoint)
-	if uerr != nil || !strings.Contains(endpoint, "://") {
-		return proto, host, scheme
-	}
-	scheme = url.Scheme
-
-	// strip scheme:// prefix since grpc dials by host
-	host = url.Host
-	switch url.Scheme {
-	case "http", "https":
-	case "unix", "unixs":
-		proto = "unix"
-		host = url.Host + url.Path
-	default:
-		proto, host = "", ""
-	}
-	return proto, host, scheme
-}
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/err.go b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/err.go
index c70ce15..9e04378 100644
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/err.go
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/err.go
@@ -22,13 +22,18 @@
 
 // NewErr returns a picker that always returns err on "Pick".
 func NewErr(err error) Picker {
-	return &errPicker{err: err}
+	return &errPicker{p: Error, err: err}
 }
 
 type errPicker struct {
+	p   Policy
 	err error
 }
 
-func (p *errPicker) Pick(context.Context, balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
-	return nil, nil, p.err
+func (ep *errPicker) String() string {
+	return ep.p.String()
+}
+
+func (ep *errPicker) Pick(context.Context, balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
+	return nil, nil, ep.err
 }
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker.go b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker.go
index 7ea761b..bd1a5d2 100644
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker.go
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker.go
@@ -15,10 +15,77 @@
 package picker
 
 import (
+	"fmt"
+
+	"go.uber.org/zap"
 	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/resolver"
 )
 
 // Picker defines balancer Picker methods.
 type Picker interface {
 	balancer.Picker
+	String() string
+}
+
+// Config defines picker configuration.
+type Config struct {
+	// Policy specifies etcd clientv3's built in balancer policy.
+	Policy Policy
+
+	// Logger defines picker logging object.
+	Logger *zap.Logger
+
+	// SubConnToResolverAddress maps each gRPC sub-connection to an address.
+	// Basically, it is a list of addresses that the Picker can pick from.
+	SubConnToResolverAddress map[balancer.SubConn]resolver.Address
+}
+
+// Policy defines balancer picker policy.
+type Policy uint8
+
+const (
+	// Error is error picker policy.
+	Error Policy = iota
+
+	// RoundrobinBalanced balances loads over multiple endpoints
+	// and implements failover in roundrobin fashion.
+	RoundrobinBalanced
+
+	// Custom defines custom balancer picker.
+	// TODO: custom picker is not supported yet.
+	Custom
+)
+
+func (p Policy) String() string {
+	switch p {
+	case Error:
+		return "picker-error"
+
+	case RoundrobinBalanced:
+		return "picker-roundrobin-balanced"
+
+	case Custom:
+		panic("'custom' picker policy is not supported yet")
+
+	default:
+		panic(fmt.Errorf("invalid balancer picker policy (%d)", p))
+	}
+}
+
+// New creates a new Picker.
+func New(cfg Config) Picker {
+	switch cfg.Policy {
+	case Error:
+		panic("'error' picker policy is not supported here; use 'picker.NewErr'")
+
+	case RoundrobinBalanced:
+		return newRoundrobinBalanced(cfg)
+
+	case Custom:
+		panic("'custom' picker policy is not supported yet")
+
+	default:
+		panic(fmt.Errorf("invalid balancer picker policy (%d)", cfg.Policy))
+	}
 }
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker_policy.go b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker_policy.go
deleted file mode 100644
index 7bca39c..0000000
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/picker_policy.go
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright 2018 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 picker
-
-import "fmt"
-
-// Policy defines balancer picker policy.
-type Policy uint8
-
-const (
-	// TODO: custom picker is not supported yet.
-	// custom defines custom balancer picker.
-	custom Policy = iota
-
-	// RoundrobinBalanced balance loads over multiple endpoints
-	// and implements failover in roundrobin fashion.
-	RoundrobinBalanced Policy = iota
-
-	// TODO: only send loads to pinned address "RoundrobinFailover"
-	// just like how 3.3 client works
-	//
-	// TODO: prioritize leader
-	// TODO: health-check
-	// TODO: weighted roundrobin
-	// TODO: power of two random choice
-)
-
-func (p Policy) String() string {
-	switch p {
-	case custom:
-		panic("'custom' picker policy is not supported yet")
-	case RoundrobinBalanced:
-		return "etcd-client-roundrobin-balanced"
-	default:
-		panic(fmt.Errorf("invalid balancer picker policy (%d)", p))
-	}
-}
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/roundrobin_balanced.go b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/roundrobin_balanced.go
index b043d57..1b8b285 100644
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/picker/roundrobin_balanced.go
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/picker/roundrobin_balanced.go
@@ -24,32 +24,33 @@
 	"google.golang.org/grpc/resolver"
 )
 
-// NewRoundrobinBalanced returns a new roundrobin balanced picker.
-func NewRoundrobinBalanced(
-	lg *zap.Logger,
-	scs []balancer.SubConn,
-	addrToSc map[resolver.Address]balancer.SubConn,
-	scToAddr map[balancer.SubConn]resolver.Address,
-) Picker {
+// newRoundrobinBalanced returns a new roundrobin balanced picker.
+func newRoundrobinBalanced(cfg Config) Picker {
+	scs := make([]balancer.SubConn, 0, len(cfg.SubConnToResolverAddress))
+	for sc := range cfg.SubConnToResolverAddress {
+		scs = append(scs, sc)
+	}
 	return &rrBalanced{
-		lg:       lg,
+		p:        RoundrobinBalanced,
+		lg:       cfg.Logger,
 		scs:      scs,
-		addrToSc: addrToSc,
-		scToAddr: scToAddr,
+		scToAddr: cfg.SubConnToResolverAddress,
 	}
 }
 
 type rrBalanced struct {
+	p Policy
+
 	lg *zap.Logger
 
-	mu   sync.RWMutex
-	next int
-	scs  []balancer.SubConn
-
-	addrToSc map[resolver.Address]balancer.SubConn
+	mu       sync.RWMutex
+	next     int
+	scs      []balancer.SubConn
 	scToAddr map[balancer.SubConn]resolver.Address
 }
 
+func (rb *rrBalanced) String() string { return rb.p.String() }
+
 // Pick is called for every client request.
 func (rb *rrBalanced) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
 	rb.mu.RLock()
@@ -68,6 +69,7 @@
 
 	rb.lg.Debug(
 		"picked",
+		zap.String("picker", rb.p.String()),
 		zap.String("address", picked),
 		zap.Int("subconn-index", cur),
 		zap.Int("subconn-size", n),
@@ -77,6 +79,7 @@
 		// TODO: error handling?
 		fss := []zapcore.Field{
 			zap.Error(info.Err),
+			zap.String("picker", rb.p.String()),
 			zap.String("address", picked),
 			zap.Bool("success", info.Err == nil),
 			zap.Bool("bytes-sent", info.BytesSent),
diff --git a/vendor/go.etcd.io/etcd/clientv3/balancer/utils.go b/vendor/go.etcd.io/etcd/clientv3/balancer/utils.go
index a11faeb..48eb875 100644
--- a/vendor/go.etcd.io/etcd/clientv3/balancer/utils.go
+++ b/vendor/go.etcd.io/etcd/clientv3/balancer/utils.go
@@ -29,9 +29,9 @@
 	return fmt.Sprintf("%p", sc)
 }
 
-func scsToStrings(scs map[resolver.Address]balancer.SubConn) (ss []string) {
+func scsToStrings(scs map[balancer.SubConn]resolver.Address) (ss []string) {
 	ss = make([]string, 0, len(scs))
-	for a, sc := range scs {
+	for sc, a := range scs {
 		ss = append(ss, fmt.Sprintf("%s (%s)", a.Addr, scToString(sc)))
 	}
 	sort.Strings(ss)
diff --git a/vendor/go.etcd.io/etcd/clientv3/client.go b/vendor/go.etcd.io/etcd/clientv3/client.go
index b91cbf9..d6000a8 100644
--- a/vendor/go.etcd.io/etcd/clientv3/client.go
+++ b/vendor/go.etcd.io/etcd/clientv3/client.go
@@ -16,7 +16,6 @@
 
 import (
 	"context"
-	"crypto/tls"
 	"errors"
 	"fmt"
 	"net"
@@ -30,12 +29,13 @@
 	"go.etcd.io/etcd/clientv3/balancer"
 	"go.etcd.io/etcd/clientv3/balancer/picker"
 	"go.etcd.io/etcd/clientv3/balancer/resolver/endpoint"
+	"go.etcd.io/etcd/clientv3/credentials"
 	"go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
 	"go.etcd.io/etcd/pkg/logutil"
 	"go.uber.org/zap"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/credentials"
+	grpccredentials "google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
@@ -51,12 +51,17 @@
 func init() {
 	lg := zap.NewNop()
 	if os.Getenv("ETCD_CLIENT_DEBUG") != "" {
+		lcfg := logutil.DefaultZapLoggerConfig
+		lcfg.Level = zap.NewAtomicLevelAt(zap.DebugLevel)
+
 		var err error
-		lg, err = zap.NewProductionConfig().Build() // info level logging
+		lg, err = lcfg.Build() // info level logging
 		if err != nil {
 			panic(err)
 		}
 	}
+
+	// TODO: support custom balancer
 	balancer.RegisterBuilder(balancer.Config{
 		Policy: picker.RoundrobinBalanced,
 		Name:   roundRobinBalancerName,
@@ -76,7 +81,7 @@
 	conn *grpc.ClientConn
 
 	cfg           Config
-	creds         *credentials.TransportCredentials
+	creds         grpccredentials.TransportCredentials
 	resolverGroup *endpoint.ResolverGroup
 	mu            *sync.RWMutex
 
@@ -86,9 +91,8 @@
 	// Username is a user name for authentication.
 	Username string
 	// Password is a password for authentication.
-	Password string
-	// tokenCred is an instance of WithPerRPCCredentials()'s argument
-	tokenCred *authTokenCredential
+	Password        string
+	authTokenBundle credentials.Bundle
 
 	callOpts []grpc.CallOption
 
@@ -125,8 +129,12 @@
 // Close shuts down the client's etcd connections.
 func (c *Client) Close() error {
 	c.cancel()
-	c.Watcher.Close()
-	c.Lease.Close()
+	if c.Watcher != nil {
+		c.Watcher.Close()
+	}
+	if c.Lease != nil {
+		c.Lease.Close()
+	}
 	if c.resolverGroup != nil {
 		c.resolverGroup.Close()
 	}
@@ -193,24 +201,7 @@
 	}
 }
 
-type authTokenCredential struct {
-	token   string
-	tokenMu *sync.RWMutex
-}
-
-func (cred authTokenCredential) RequireTransportSecurity() bool {
-	return false
-}
-
-func (cred authTokenCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) {
-	cred.tokenMu.RLock()
-	defer cred.tokenMu.RUnlock()
-	return map[string]string{
-		rpctypes.TokenFieldNameGRPC: cred.token,
-	}, nil
-}
-
-func (c *Client) processCreds(scheme string) (creds *credentials.TransportCredentials) {
+func (c *Client) processCreds(scheme string) (creds grpccredentials.TransportCredentials) {
 	creds = c.creds
 	switch scheme {
 	case "unix":
@@ -220,9 +211,7 @@
 		if creds != nil {
 			break
 		}
-		tlsconfig := &tls.Config{}
-		emptyCreds := credentials.NewTLS(tlsconfig)
-		creds = &emptyCreds
+		creds = credentials.NewBundle(credentials.Config{}).TransportCredentials()
 	default:
 		creds = nil
 	}
@@ -230,7 +219,7 @@
 }
 
 // dialSetupOpts gives the dial opts prior to any authentication.
-func (c *Client) dialSetupOpts(creds *credentials.TransportCredentials, dopts ...grpc.DialOption) (opts []grpc.DialOption, err error) {
+func (c *Client) dialSetupOpts(creds grpccredentials.TransportCredentials, dopts ...grpc.DialOption) (opts []grpc.DialOption, err error) {
 	if c.cfg.DialKeepAliveTime > 0 {
 		params := keepalive.ClientParameters{
 			Time:                c.cfg.DialKeepAliveTime,
@@ -255,7 +244,7 @@
 	opts = append(opts, grpc.WithDialer(f))
 
 	if creds != nil {
-		opts = append(opts, grpc.WithTransportCredentials(*creds))
+		opts = append(opts, grpc.WithTransportCredentials(creds))
 	} else {
 		opts = append(opts, grpc.WithInsecure())
 	}
@@ -289,8 +278,8 @@
 	var err error // return last error in a case of fail
 	var auth *authenticator
 
-	for i := 0; i < len(c.cfg.Endpoints); i++ {
-		ep := c.cfg.Endpoints[i]
+	eps := c.Endpoints()
+	for _, ep := range eps {
 		// use dial options without dopts to avoid reusing the client balancer
 		var dOpts []grpc.DialOption
 		_, host, _ := endpoint.ParseEndpoint(ep)
@@ -318,10 +307,7 @@
 			continue
 		}
 
-		c.tokenCred.tokenMu.Lock()
-		c.tokenCred.token = resp.Token
-		c.tokenCred.tokenMu.Unlock()
-
+		c.authTokenBundle.UpdateAuthToken(resp.Token)
 		return nil
 	}
 
@@ -338,16 +324,14 @@
 }
 
 // dial configures and dials any grpc balancer target.
-func (c *Client) dial(target string, creds *credentials.TransportCredentials, dopts ...grpc.DialOption) (*grpc.ClientConn, error) {
+func (c *Client) dial(target string, creds grpccredentials.TransportCredentials, dopts ...grpc.DialOption) (*grpc.ClientConn, error) {
 	opts, err := c.dialSetupOpts(creds, dopts...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to configure dialer: %v", err)
 	}
 
 	if c.Username != "" && c.Password != "" {
-		c.tokenCred = &authTokenCredential{
-			tokenMu: &sync.RWMutex{},
-		}
+		c.authTokenBundle = credentials.NewBundle(credentials.Config{})
 
 		ctx, cancel := c.ctx, func() {}
 		if c.cfg.DialTimeout > 0 {
@@ -364,7 +348,7 @@
 				return nil, err
 			}
 		} else {
-			opts = append(opts, grpc.WithPerRPCCredentials(c.tokenCred))
+			opts = append(opts, grpc.WithPerRPCCredentials(c.authTokenBundle.PerRPCCredentials()))
 		}
 		cancel()
 	}
@@ -385,26 +369,25 @@
 	return conn, nil
 }
 
-func (c *Client) directDialCreds(ep string) *credentials.TransportCredentials {
+func (c *Client) directDialCreds(ep string) grpccredentials.TransportCredentials {
 	_, hostPort, scheme := endpoint.ParseEndpoint(ep)
 	creds := c.creds
 	if len(scheme) != 0 {
 		creds = c.processCreds(scheme)
 		if creds != nil {
-			c := *creds
-			clone := c.Clone()
+			clone := creds.Clone()
 			// Set the server name must to the endpoint hostname without port since grpc
 			// otherwise attempts to check if x509 cert is valid for the full endpoint
 			// including the scheme and port, which fails.
 			host, _ := endpoint.ParseHostPort(hostPort)
 			clone.OverrideServerName(host)
-			creds = &clone
+			creds = clone
 		}
 	}
 	return creds
 }
 
-func (c *Client) dialWithBalancerCreds(ep string) *credentials.TransportCredentials {
+func (c *Client) dialWithBalancerCreds(ep string) grpccredentials.TransportCredentials {
 	_, _, scheme := endpoint.ParseEndpoint(ep)
 	creds := c.creds
 	if len(scheme) != 0 {
@@ -424,10 +407,9 @@
 	if cfg == nil {
 		cfg = &Config{}
 	}
-	var creds *credentials.TransportCredentials
+	var creds grpccredentials.TransportCredentials
 	if cfg.TLS != nil {
-		c := credentials.NewTLS(cfg.TLS)
-		creds = &c
+		creds = credentials.NewBundle(credentials.Config{TLSConfig: cfg.TLS}).TransportCredentials()
 	}
 
 	// use a temporary skeleton client to bootstrap first connection
@@ -541,13 +523,17 @@
 
 func (c *Client) checkVersion() (err error) {
 	var wg sync.WaitGroup
-	errc := make(chan error, len(c.cfg.Endpoints))
+
+	eps := c.Endpoints()
+	errc := make(chan error, len(eps))
 	ctx, cancel := context.WithCancel(c.ctx)
 	if c.cfg.DialTimeout > 0 {
-		ctx, cancel = context.WithTimeout(ctx, c.cfg.DialTimeout)
+		cancel()
+		ctx, cancel = context.WithTimeout(c.ctx, c.cfg.DialTimeout)
 	}
-	wg.Add(len(c.cfg.Endpoints))
-	for _, ep := range c.cfg.Endpoints {
+
+	wg.Add(len(eps))
+	for _, ep := range eps {
 		// if cluster is current, any endpoint gives a recent version
 		go func(e string) {
 			defer wg.Done()
@@ -559,8 +545,15 @@
 			vs := strings.Split(resp.Version, ".")
 			maj, min := 0, 0
 			if len(vs) >= 2 {
-				maj, _ = strconv.Atoi(vs[0])
-				min, rerr = strconv.Atoi(vs[1])
+				var serr error
+				if maj, serr = strconv.Atoi(vs[0]); serr != nil {
+					errc <- serr
+					return
+				}
+				if min, serr = strconv.Atoi(vs[1]); serr != nil {
+					errc <- serr
+					return
+				}
 			}
 			if maj < 3 || (maj == 3 && min < 2) {
 				rerr = ErrOldCluster
@@ -569,7 +562,7 @@
 		}(ep)
 	}
 	// wait for success
-	for i := 0; i < len(c.cfg.Endpoints); i++ {
+	for range eps {
 		if err = <-errc; err == nil {
 			break
 		}
@@ -609,10 +602,13 @@
 	if err == nil {
 		return false
 	}
-	ev, _ := status.FromError(err)
-	// Unavailable codes mean the system will be right back.
-	// (e.g., can't connect, lost leader)
-	return ev.Code() == codes.Unavailable
+	ev, ok := status.FromError(err)
+	if ok {
+		// Unavailable codes mean the system will be right back.
+		// (e.g., can't connect, lost leader)
+		return ev.Code() == codes.Unavailable
+	}
+	return false
 }
 
 func toErr(ctx context.Context, err error) error {
@@ -632,9 +628,6 @@
 			if ctx.Err() != nil {
 				err = ctx.Err()
 			}
-		case codes.Unavailable:
-		case codes.FailedPrecondition:
-			err = grpc.ErrClientConnClosing
 		}
 	}
 	return err
@@ -654,16 +647,19 @@
 	if err == nil {
 		return false
 	}
-	// >= gRPC v1.10.x
+
+	// >= gRPC v1.23.x
 	s, ok := status.FromError(err)
 	if ok {
 		// connection is canceled or server has already closed the connection
 		return s.Code() == codes.Canceled || s.Message() == "transport is closing"
 	}
+
 	// >= gRPC v1.10.x
 	if err == context.Canceled {
 		return true
 	}
+
 	// <= gRPC v1.7.x returns 'errors.New("grpc: the client connection is closing")'
 	return strings.Contains(err.Error(), "grpc: the client connection is closing")
 }
diff --git a/vendor/go.etcd.io/etcd/clientv3/concurrency/mutex.go b/vendor/go.etcd.io/etcd/clientv3/concurrency/mutex.go
index 0135341..306470b 100644
--- a/vendor/go.etcd.io/etcd/clientv3/concurrency/mutex.go
+++ b/vendor/go.etcd.io/etcd/clientv3/concurrency/mutex.go
@@ -16,6 +16,7 @@
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sync"
 
@@ -23,6 +24,9 @@
 	pb "go.etcd.io/etcd/etcdserver/etcdserverpb"
 )
 
+// ErrLocked is returned by TryLock when Mutex is already locked by another session.
+var ErrLocked = errors.New("mutex: Locked by another session")
+
 // Mutex implements the sync Locker interface with etcd
 type Mutex struct {
 	s *Session
@@ -37,9 +41,56 @@
 	return &Mutex{s, pfx + "/", "", -1, nil}
 }
 
+// TryLock locks the mutex if not already locked by another session.
+// If lock is held by another session, return immediately after attempting necessary cleanup
+// The ctx argument is used for the sending/receiving Txn RPC.
+func (m *Mutex) TryLock(ctx context.Context) error {
+	resp, err := m.tryAcquire(ctx)
+	if err != nil {
+		return err
+	}
+	// if no key on prefix / the minimum rev is key, already hold the lock
+	ownerKey := resp.Responses[1].GetResponseRange().Kvs
+	if len(ownerKey) == 0 || ownerKey[0].CreateRevision == m.myRev {
+		m.hdr = resp.Header
+		return nil
+	}
+	client := m.s.Client()
+	// Cannot lock, so delete the key
+	if _, err := client.Delete(ctx, m.myKey); err != nil {
+		return err
+	}
+	m.myKey = "\x00"
+	m.myRev = -1
+	return ErrLocked
+}
+
 // Lock locks the mutex with a cancelable context. If the context is canceled
 // while trying to acquire the lock, the mutex tries to clean its stale lock entry.
 func (m *Mutex) Lock(ctx context.Context) error {
+	resp, err := m.tryAcquire(ctx)
+	if err != nil {
+		return err
+	}
+	// if no key on prefix / the minimum rev is key, already hold the lock
+	ownerKey := resp.Responses[1].GetResponseRange().Kvs
+	if len(ownerKey) == 0 || ownerKey[0].CreateRevision == m.myRev {
+		m.hdr = resp.Header
+		return nil
+	}
+	client := m.s.Client()
+	// wait for deletion revisions prior to myKey
+	hdr, werr := waitDeletes(ctx, client, m.pfx, m.myRev-1)
+	// release lock key if wait failed
+	if werr != nil {
+		m.Unlock(client.Ctx())
+	} else {
+		m.hdr = hdr
+	}
+	return werr
+}
+
+func (m *Mutex) tryAcquire(ctx context.Context) (*v3.TxnResponse, error) {
 	s := m.s
 	client := m.s.Client()
 
@@ -53,28 +104,13 @@
 	getOwner := v3.OpGet(m.pfx, v3.WithFirstCreate()...)
 	resp, err := client.Txn(ctx).If(cmp).Then(put, getOwner).Else(get, getOwner).Commit()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	m.myRev = resp.Header.Revision
 	if !resp.Succeeded {
 		m.myRev = resp.Responses[0].GetResponseRange().Kvs[0].CreateRevision
 	}
-	// if no key on prefix / the minimum rev is key, already hold the lock
-	ownerKey := resp.Responses[1].GetResponseRange().Kvs
-	if len(ownerKey) == 0 || ownerKey[0].CreateRevision == m.myRev {
-		m.hdr = resp.Header
-		return nil
-	}
-
-	// wait for deletion revisions prior to myKey
-	hdr, werr := waitDeletes(ctx, client, m.pfx, m.myRev-1)
-	// release lock key if wait failed
-	if werr != nil {
-		m.Unlock(client.Ctx())
-	} else {
-		m.hdr = hdr
-	}
-	return werr
+	return resp, nil
 }
 
 func (m *Mutex) Unlock(ctx context.Context) error {
diff --git a/vendor/go.etcd.io/etcd/clientv3/config.go b/vendor/go.etcd.io/etcd/clientv3/config.go
index bd03768..11d447d 100644
--- a/vendor/go.etcd.io/etcd/clientv3/config.go
+++ b/vendor/go.etcd.io/etcd/clientv3/config.go
@@ -68,6 +68,8 @@
 	RejectOldCluster bool `json:"reject-old-cluster"`
 
 	// DialOptions is a list of dial options for the grpc client (e.g., for interceptors).
+	// For example, pass "grpc.WithBlock()" to block until the underlying connection is up.
+	// Without this, Dial returns immediately and connecting the server happens in background.
 	DialOptions []grpc.DialOption
 
 	// Context is the default client context; it can be used to cancel grpc dial out and
@@ -81,4 +83,6 @@
 
 	// PermitWithoutStream when set will allow client to send keepalive pings to server without any active streams(RPCs).
 	PermitWithoutStream bool `json:"permit-without-stream"`
+
+	// TODO: support custom balancer picker
 }
diff --git a/vendor/go.etcd.io/etcd/clientv3/credentials/credentials.go b/vendor/go.etcd.io/etcd/clientv3/credentials/credentials.go
new file mode 100644
index 0000000..e6fd75c
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/clientv3/credentials/credentials.go
@@ -0,0 +1,155 @@
+// 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 credentials implements gRPC credential interface with etcd specific logic.
+// e.g., client handshake with custom authority parameter
+package credentials
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"sync"
+
+	"go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
+	grpccredentials "google.golang.org/grpc/credentials"
+)
+
+// Config defines gRPC credential configuration.
+type Config struct {
+	TLSConfig *tls.Config
+}
+
+// Bundle defines gRPC credential interface.
+type Bundle interface {
+	grpccredentials.Bundle
+	UpdateAuthToken(token string)
+}
+
+// NewBundle constructs a new gRPC credential bundle.
+func NewBundle(cfg Config) Bundle {
+	return &bundle{
+		tc: newTransportCredential(cfg.TLSConfig),
+		rc: newPerRPCCredential(),
+	}
+}
+
+// bundle implements "grpccredentials.Bundle" interface.
+type bundle struct {
+	tc *transportCredential
+	rc *perRPCCredential
+}
+
+func (b *bundle) TransportCredentials() grpccredentials.TransportCredentials {
+	return b.tc
+}
+
+func (b *bundle) PerRPCCredentials() grpccredentials.PerRPCCredentials {
+	return b.rc
+}
+
+func (b *bundle) NewWithMode(mode string) (grpccredentials.Bundle, error) {
+	// no-op
+	return nil, nil
+}
+
+// transportCredential implements "grpccredentials.TransportCredentials" interface.
+type transportCredential struct {
+	gtc grpccredentials.TransportCredentials
+}
+
+func newTransportCredential(cfg *tls.Config) *transportCredential {
+	return &transportCredential{
+		gtc: grpccredentials.NewTLS(cfg),
+	}
+}
+
+func (tc *transportCredential) ClientHandshake(ctx context.Context, authority string, rawConn net.Conn) (net.Conn, grpccredentials.AuthInfo, error) {
+	// Only overwrite when authority is an IP address!
+	// Let's say, a server runs SRV records on "etcd.local" that resolves
+	// to "m1.etcd.local", and its SAN field also includes "m1.etcd.local".
+	// But what if SAN does not include its resolved IP address (e.g. 127.0.0.1)?
+	// Then, the server should only authenticate using its DNS hostname "m1.etcd.local",
+	// instead of overwriting it with its IP address.
+	// And we do not overwrite "localhost" either. Only overwrite IP addresses!
+	if isIP(authority) {
+		target := rawConn.RemoteAddr().String()
+		if authority != target {
+			// When user dials with "grpc.WithDialer", "grpc.DialContext" "cc.parsedTarget"
+			// update only happens once. This is problematic, because when TLS is enabled,
+			// retries happen through "grpc.WithDialer" with static "cc.parsedTarget" from
+			// the initial dial call.
+			// If the server authenticates by IP addresses, we want to set a new endpoint as
+			// a new authority. Otherwise
+			// "transport: authentication handshake failed: x509: certificate is valid for 127.0.0.1, 192.168.121.180, not 192.168.223.156"
+			// when the new dial target is "192.168.121.180" whose certificate host name is also "192.168.121.180"
+			// but client tries to authenticate with previously set "cc.parsedTarget" field "192.168.223.156"
+			authority = target
+		}
+	}
+	return tc.gtc.ClientHandshake(ctx, authority, rawConn)
+}
+
+// return true if given string is an IP.
+func isIP(ep string) bool {
+	return net.ParseIP(ep) != nil
+}
+
+func (tc *transportCredential) ServerHandshake(rawConn net.Conn) (net.Conn, grpccredentials.AuthInfo, error) {
+	return tc.gtc.ServerHandshake(rawConn)
+}
+
+func (tc *transportCredential) Info() grpccredentials.ProtocolInfo {
+	return tc.gtc.Info()
+}
+
+func (tc *transportCredential) Clone() grpccredentials.TransportCredentials {
+	return &transportCredential{
+		gtc: tc.gtc.Clone(),
+	}
+}
+
+func (tc *transportCredential) OverrideServerName(serverNameOverride string) error {
+	return tc.gtc.OverrideServerName(serverNameOverride)
+}
+
+// perRPCCredential implements "grpccredentials.PerRPCCredentials" interface.
+type perRPCCredential struct {
+	authToken   string
+	authTokenMu sync.RWMutex
+}
+
+func newPerRPCCredential() *perRPCCredential { return &perRPCCredential{} }
+
+func (rc *perRPCCredential) RequireTransportSecurity() bool { return false }
+
+func (rc *perRPCCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) {
+	rc.authTokenMu.RLock()
+	authToken := rc.authToken
+	rc.authTokenMu.RUnlock()
+	return map[string]string{rpctypes.TokenFieldNameGRPC: authToken}, nil
+}
+
+func (b *bundle) UpdateAuthToken(token string) {
+	if b.rc == nil {
+		return
+	}
+	b.rc.UpdateAuthToken(token)
+}
+
+func (rc *perRPCCredential) UpdateAuthToken(token string) {
+	rc.authTokenMu.Lock()
+	rc.authToken = token
+	rc.authTokenMu.Unlock()
+}
diff --git a/vendor/go.etcd.io/etcd/clientv3/doc.go b/vendor/go.etcd.io/etcd/clientv3/doc.go
index 01a3f59..913cd28 100644
--- a/vendor/go.etcd.io/etcd/clientv3/doc.go
+++ b/vendor/go.etcd.io/etcd/clientv3/doc.go
@@ -90,7 +90,7 @@
 //		// with etcd clientv3 <= v3.3
 //		if err == context.Canceled {
 //			// grpc balancer calls 'Get' with an inflight client.Close
-//		} else if err == grpc.ErrClientConnClosing {
+//		} else if err == grpc.ErrClientConnClosing { // <= gRCP v1.7.x
 //			// grpc balancer calls 'Get' after client.Close.
 //		}
 //		// with etcd clientv3 >= v3.4
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes/error.go b/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes/error.go
index 3bbc26b..e6a2814 100644
--- a/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes/error.go
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes/error.go
@@ -54,6 +54,7 @@
 	ErrGRPCUserNotFound         = status.New(codes.FailedPrecondition, "etcdserver: user name not found").Err()
 	ErrGRPCRoleAlreadyExist     = status.New(codes.FailedPrecondition, "etcdserver: role name already exists").Err()
 	ErrGRPCRoleNotFound         = status.New(codes.FailedPrecondition, "etcdserver: role name not found").Err()
+	ErrGRPCRoleEmpty            = status.New(codes.InvalidArgument, "etcdserver: role name is empty").Err()
 	ErrGRPCAuthFailed           = status.New(codes.InvalidArgument, "etcdserver: authentication failed, invalid user ID or password").Err()
 	ErrGRPCPermissionDenied     = status.New(codes.PermissionDenied, "etcdserver: permission denied").Err()
 	ErrGRPCRoleNotGranted       = status.New(codes.FailedPrecondition, "etcdserver: role is not granted to the user").Err()
@@ -110,6 +111,7 @@
 		ErrorDesc(ErrGRPCUserNotFound):         ErrGRPCUserNotFound,
 		ErrorDesc(ErrGRPCRoleAlreadyExist):     ErrGRPCRoleAlreadyExist,
 		ErrorDesc(ErrGRPCRoleNotFound):         ErrGRPCRoleNotFound,
+		ErrorDesc(ErrGRPCRoleEmpty):            ErrGRPCRoleEmpty,
 		ErrorDesc(ErrGRPCAuthFailed):           ErrGRPCAuthFailed,
 		ErrorDesc(ErrGRPCPermissionDenied):     ErrGRPCPermissionDenied,
 		ErrorDesc(ErrGRPCRoleNotGranted):       ErrGRPCRoleNotGranted,
@@ -168,6 +170,7 @@
 	ErrUserNotFound         = Error(ErrGRPCUserNotFound)
 	ErrRoleAlreadyExist     = Error(ErrGRPCRoleAlreadyExist)
 	ErrRoleNotFound         = Error(ErrGRPCRoleNotFound)
+	ErrRoleEmpty            = Error(ErrGRPCRoleEmpty)
 	ErrAuthFailed           = Error(ErrGRPCAuthFailed)
 	ErrPermissionDenied     = Error(ErrGRPCPermissionDenied)
 	ErrRoleNotGranted       = Error(ErrGRPCRoleNotGranted)
diff --git a/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.pb.go b/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.pb.go
index 73efc30..199ee62 100644
--- a/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.pb.go
+++ b/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.pb.go
@@ -4537,7 +4537,7 @@
 	AuthDisable(ctx context.Context, in *AuthDisableRequest, opts ...grpc.CallOption) (*AuthDisableResponse, error)
 	// Authenticate processes an authenticate request.
 	Authenticate(ctx context.Context, in *AuthenticateRequest, opts ...grpc.CallOption) (*AuthenticateResponse, error)
-	// UserAdd adds a new user.
+	// UserAdd adds a new user. User name cannot be empty.
 	UserAdd(ctx context.Context, in *AuthUserAddRequest, opts ...grpc.CallOption) (*AuthUserAddResponse, error)
 	// UserGet gets detailed user information.
 	UserGet(ctx context.Context, in *AuthUserGetRequest, opts ...grpc.CallOption) (*AuthUserGetResponse, error)
@@ -4551,7 +4551,7 @@
 	UserGrantRole(ctx context.Context, in *AuthUserGrantRoleRequest, opts ...grpc.CallOption) (*AuthUserGrantRoleResponse, error)
 	// UserRevokeRole revokes a role of specified user.
 	UserRevokeRole(ctx context.Context, in *AuthUserRevokeRoleRequest, opts ...grpc.CallOption) (*AuthUserRevokeRoleResponse, error)
-	// RoleAdd adds a new role.
+	// RoleAdd adds a new role. Role name cannot be empty.
 	RoleAdd(ctx context.Context, in *AuthRoleAddRequest, opts ...grpc.CallOption) (*AuthRoleAddResponse, error)
 	// RoleGet gets detailed role information.
 	RoleGet(ctx context.Context, in *AuthRoleGetRequest, opts ...grpc.CallOption) (*AuthRoleGetResponse, error)
@@ -4726,7 +4726,7 @@
 	AuthDisable(context.Context, *AuthDisableRequest) (*AuthDisableResponse, error)
 	// Authenticate processes an authenticate request.
 	Authenticate(context.Context, *AuthenticateRequest) (*AuthenticateResponse, error)
-	// UserAdd adds a new user.
+	// UserAdd adds a new user. User name cannot be empty.
 	UserAdd(context.Context, *AuthUserAddRequest) (*AuthUserAddResponse, error)
 	// UserGet gets detailed user information.
 	UserGet(context.Context, *AuthUserGetRequest) (*AuthUserGetResponse, error)
@@ -4740,7 +4740,7 @@
 	UserGrantRole(context.Context, *AuthUserGrantRoleRequest) (*AuthUserGrantRoleResponse, error)
 	// UserRevokeRole revokes a role of specified user.
 	UserRevokeRole(context.Context, *AuthUserRevokeRoleRequest) (*AuthUserRevokeRoleResponse, error)
-	// RoleAdd adds a new role.
+	// RoleAdd adds a new role. Role name cannot be empty.
 	RoleAdd(context.Context, *AuthRoleAddRequest) (*AuthRoleAddResponse, error)
 	// RoleGet gets detailed role information.
 	RoleGet(context.Context, *AuthRoleGetRequest) (*AuthRoleGetResponse, error)
diff --git a/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.proto b/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.proto
index 565f8fa..423eaba 100644
--- a/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.proto
+++ b/vendor/go.etcd.io/etcd/etcdserver/etcdserverpb/rpc.proto
@@ -264,7 +264,7 @@
     };
   }
 
-  // UserAdd adds a new user.
+  // UserAdd adds a new user. User name cannot be empty.
   rpc UserAdd(AuthUserAddRequest) returns (AuthUserAddResponse) {
       option (google.api.http) = {
         post: "/v3/auth/user/add"
@@ -320,7 +320,7 @@
     };
   }
 
-  // RoleAdd adds a new role.
+  // RoleAdd adds a new role. Role name cannot be empty.
   rpc RoleAdd(AuthRoleAddRequest) returns (AuthRoleAddResponse) {
       option (google.api.http) = {
         post: "/v3/auth/role/add"
diff --git a/vendor/go.etcd.io/etcd/pkg/logutil/log_level.go b/vendor/go.etcd.io/etcd/pkg/logutil/log_level.go
new file mode 100644
index 0000000..d57e173
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/pkg/logutil/log_level.go
@@ -0,0 +1,70 @@
+// 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 logutil
+
+import (
+	"fmt"
+
+	"github.com/coreos/pkg/capnslog"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+var DefaultLogLevel = "info"
+
+// ConvertToZapLevel converts log level string to zapcore.Level.
+func ConvertToZapLevel(lvl string) zapcore.Level {
+	switch lvl {
+	case "debug":
+		return zap.DebugLevel
+	case "info":
+		return zap.InfoLevel
+	case "warn":
+		return zap.WarnLevel
+	case "error":
+		return zap.ErrorLevel
+	case "dpanic":
+		return zap.DPanicLevel
+	case "panic":
+		return zap.PanicLevel
+	case "fatal":
+		return zap.FatalLevel
+	default:
+		panic(fmt.Sprintf("unknown level %q", lvl))
+	}
+}
+
+// ConvertToCapnslogLogLevel convert log level string to capnslog.LogLevel.
+// TODO: deprecate this in 3.5
+func ConvertToCapnslogLogLevel(lvl string) capnslog.LogLevel {
+	switch lvl {
+	case "debug":
+		return capnslog.DEBUG
+	case "info":
+		return capnslog.INFO
+	case "warn":
+		return capnslog.WARNING
+	case "error":
+		return capnslog.ERROR
+	case "dpanic":
+		return capnslog.CRITICAL
+	case "panic":
+		return capnslog.CRITICAL
+	case "fatal":
+		return capnslog.CRITICAL
+	default:
+		panic(fmt.Sprintf("unknown level %q", lvl))
+	}
+}
diff --git a/vendor/go.etcd.io/etcd/pkg/logutil/zap.go b/vendor/go.etcd.io/etcd/pkg/logutil/zap.go
index 313d914..8fc6e03 100644
--- a/vendor/go.etcd.io/etcd/pkg/logutil/zap.go
+++ b/vendor/go.etcd.io/etcd/pkg/logutil/zap.go
@@ -23,7 +23,7 @@
 
 // DefaultZapLoggerConfig defines default zap logger configuration.
 var DefaultZapLoggerConfig = zap.Config{
-	Level: zap.NewAtomicLevelAt(zap.InfoLevel),
+	Level: zap.NewAtomicLevelAt(ConvertToZapLevel(DefaultLogLevel)),
 
 	Development: false,
 	Sampling: &zap.SamplingConfig{
@@ -53,15 +53,12 @@
 	ErrorOutputPaths: []string{"stderr"},
 }
 
-// AddOutputPaths adds output paths to the existing output paths, resolving conflicts.
-func AddOutputPaths(cfg zap.Config, outputPaths, errorOutputPaths []string) zap.Config {
+// MergeOutputPaths merges logging output paths, resolving conflicts.
+func MergeOutputPaths(cfg zap.Config) zap.Config {
 	outputs := make(map[string]struct{})
 	for _, v := range cfg.OutputPaths {
 		outputs[v] = struct{}{}
 	}
-	for _, v := range outputPaths {
-		outputs[v] = struct{}{}
-	}
 	outputSlice := make([]string, 0)
 	if _, ok := outputs["/dev/null"]; ok {
 		// "/dev/null" to discard all
@@ -78,9 +75,6 @@
 	for _, v := range cfg.ErrorOutputPaths {
 		errOutputs[v] = struct{}{}
 	}
-	for _, v := range errorOutputPaths {
-		errOutputs[v] = struct{}{}
-	}
 	errOutputSlice := make([]string, 0)
 	if _, ok := errOutputs["/dev/null"]; ok {
 		// "/dev/null" to discard all
diff --git a/vendor/go.etcd.io/etcd/pkg/logutil/zap_raft.go b/vendor/go.etcd.io/etcd/pkg/logutil/zap_raft.go
index e92cba0..f016b30 100644
--- a/vendor/go.etcd.io/etcd/pkg/logutil/zap_raft.go
+++ b/vendor/go.etcd.io/etcd/pkg/logutil/zap_raft.go
@@ -23,7 +23,7 @@
 	"go.uber.org/zap/zapcore"
 )
 
-// NewRaftLogger converts "*zap.Logger" to "raft.Logger".
+// NewRaftLogger builds "raft.Logger" from "*zap.Config".
 func NewRaftLogger(lcfg *zap.Config) (raft.Logger, error) {
 	if lcfg == nil {
 		return nil, errors.New("nil zap.Config")
@@ -35,6 +35,11 @@
 	return &zapRaftLogger{lg: lg, sugar: lg.Sugar()}, nil
 }
 
+// NewRaftLoggerZap converts "*zap.Logger" to "raft.Logger".
+func NewRaftLoggerZap(lg *zap.Logger) raft.Logger {
+	return &zapRaftLogger{lg: lg, sugar: lg.Sugar()}
+}
+
 // NewRaftLoggerFromZapCore creates "raft.Logger" from "zap.Core"
 // and "zapcore.WriteSyncer".
 func NewRaftLoggerFromZapCore(cr zapcore.Core, syncer zapcore.WriteSyncer) raft.Logger {
diff --git a/vendor/go.etcd.io/etcd/pkg/types/set.go b/vendor/go.etcd.io/etcd/pkg/types/set.go
index c111b0c..e7a3cdc 100644
--- a/vendor/go.etcd.io/etcd/pkg/types/set.go
+++ b/vendor/go.etcd.io/etcd/pkg/types/set.go
@@ -148,6 +148,14 @@
 func (ts *tsafeSet) Equals(other Set) bool {
 	ts.m.RLock()
 	defer ts.m.RUnlock()
+
+	// If ts and other represent the same variable, avoid calling
+	// ts.us.Equals(other), to avoid double RLock bug
+	if _other, ok := other.(*tsafeSet); ok {
+		if _other == ts {
+			return true
+		}
+	}
 	return ts.us.Equals(other)
 }
 
@@ -173,6 +181,15 @@
 func (ts *tsafeSet) Sub(other Set) Set {
 	ts.m.RLock()
 	defer ts.m.RUnlock()
+
+	// If ts and other represent the same variable, avoid calling
+	// ts.us.Sub(other), to avoid double RLock bug
+	if _other, ok := other.(*tsafeSet); ok {
+		if _other == ts {
+			usResult := NewUnsafeSet()
+			return &tsafeSet{usResult, sync.RWMutex{}}
+		}
+	}
 	usResult := ts.us.Sub(other).(*unsafeSet)
 	return &tsafeSet{usResult, sync.RWMutex{}}
 }
diff --git a/vendor/go.etcd.io/etcd/raft/bootstrap.go b/vendor/go.etcd.io/etcd/raft/bootstrap.go
new file mode 100644
index 0000000..bd82b20
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/bootstrap.go
@@ -0,0 +1,80 @@
+// 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 raft
+
+import (
+	"errors"
+
+	pb "go.etcd.io/etcd/raft/raftpb"
+)
+
+// Bootstrap initializes the RawNode for first use by appending configuration
+// changes for the supplied peers. This method returns an error if the Storage
+// is nonempty.
+//
+// It is recommended that instead of calling this method, applications bootstrap
+// their state manually by setting up a Storage that has a first index > 1 and
+// which stores the desired ConfState as its InitialState.
+func (rn *RawNode) Bootstrap(peers []Peer) error {
+	if len(peers) == 0 {
+		return errors.New("must provide at least one peer to Bootstrap")
+	}
+	lastIndex, err := rn.raft.raftLog.storage.LastIndex()
+	if err != nil {
+		return err
+	}
+
+	if lastIndex != 0 {
+		return errors.New("can't bootstrap a nonempty Storage")
+	}
+
+	// We've faked out initial entries above, but nothing has been
+	// persisted. Start with an empty HardState (thus the first Ready will
+	// emit a HardState update for the app to persist).
+	rn.prevHardSt = emptyState
+
+	// TODO(tbg): remove StartNode and give the application the right tools to
+	// bootstrap the initial membership in a cleaner way.
+	rn.raft.becomeFollower(1, None)
+	ents := make([]pb.Entry, len(peers))
+	for i, peer := range peers {
+		cc := pb.ConfChange{Type: pb.ConfChangeAddNode, NodeID: peer.ID, Context: peer.Context}
+		data, err := cc.Marshal()
+		if err != nil {
+			return err
+		}
+
+		ents[i] = pb.Entry{Type: pb.EntryConfChange, Term: 1, Index: uint64(i + 1), Data: data}
+	}
+	rn.raft.raftLog.append(ents...)
+
+	// Now apply them, mainly so that the application can call Campaign
+	// immediately after StartNode in tests. Note that these nodes will
+	// be added to raft twice: here and when the application's Ready
+	// loop calls ApplyConfChange. The calls to addNode must come after
+	// all calls to raftLog.append so progress.next is set after these
+	// bootstrapping entries (it is an error if we try to append these
+	// entries since they have already been committed).
+	// We do not set raftLog.applied so the application will be able
+	// to observe all conf changes via Ready.CommittedEntries.
+	//
+	// TODO(bdarnell): These entries are still unstable; do we need to preserve
+	// the invariant that committed < unstable?
+	rn.raft.raftLog.committed = uint64(len(ents))
+	for _, peer := range peers {
+		rn.raft.applyConfChange(pb.ConfChange{NodeID: peer.ID, Type: pb.ConfChangeAddNode}.AsV2())
+	}
+	return nil
+}
diff --git a/vendor/go.etcd.io/etcd/raft/confchange/confchange.go b/vendor/go.etcd.io/etcd/raft/confchange/confchange.go
index fd75aed..a0dc486 100644
--- a/vendor/go.etcd.io/etcd/raft/confchange/confchange.go
+++ b/vendor/go.etcd.io/etcd/raft/confchange/confchange.go
@@ -41,12 +41,12 @@
 // to
 //     (1 2 3)&&(1 2 3).
 //
-// The supplied ConfChanges are then applied to the incoming majority config,
+// The supplied changes are then applied to the incoming majority config,
 // resulting in a joint configuration that in terms of the Raft thesis[1]
 // (Section 4.3) corresponds to `C_{new,old}`.
 //
 // [1]: https://github.com/ongardie/dissertation/blob/master/online-trim.pdf
-func (c Changer) EnterJoint(ccs ...pb.ConfChange) (tracker.Config, tracker.ProgressMap, error) {
+func (c Changer) EnterJoint(autoLeave bool, ccs ...pb.ConfChangeSingle) (tracker.Config, tracker.ProgressMap, error) {
 	cfg, prs, err := c.checkAndCopy()
 	if err != nil {
 		return c.err(err)
@@ -62,10 +62,7 @@
 		return c.err(err)
 	}
 	// Clear the outgoing config.
-	{
-		*outgoingPtr(&cfg.Voters) = quorum.MajorityConfig{}
-
-	}
+	*outgoingPtr(&cfg.Voters) = quorum.MajorityConfig{}
 	// Copy incoming to outgoing.
 	for id := range incoming(cfg.Voters) {
 		outgoing(cfg.Voters)[id] = struct{}{}
@@ -74,7 +71,7 @@
 	if err := c.apply(&cfg, prs, ccs...); err != nil {
 		return c.err(err)
 	}
-
+	cfg.AutoLeave = autoLeave
 	return checkAndReturn(cfg, prs)
 }
 
@@ -120,6 +117,7 @@
 		}
 	}
 	*outgoingPtr(&cfg.Voters) = nil
+	cfg.AutoLeave = false
 
 	return checkAndReturn(cfg, prs)
 }
@@ -129,7 +127,7 @@
 // will return an error if that is not the case, if the resulting quorum is
 // zero, or if the configuration is in a joint state (i.e. if there is an
 // outgoing configuration).
-func (c Changer) Simple(ccs ...pb.ConfChange) (tracker.Config, tracker.ProgressMap, error) {
+func (c Changer) Simple(ccs ...pb.ConfChangeSingle) (tracker.Config, tracker.ProgressMap, error) {
 	cfg, prs, err := c.checkAndCopy()
 	if err != nil {
 		return c.err(err)
@@ -142,7 +140,7 @@
 		return c.err(err)
 	}
 	if n := symdiff(incoming(c.Tracker.Voters), incoming(cfg.Voters)); n > 1 {
-		return tracker.Config{}, nil, errors.New("more than voter changed without entering joint config")
+		return tracker.Config{}, nil, errors.New("more than one voter changed without entering joint config")
 	}
 	if err := checkInvariants(cfg, prs); err != nil {
 		return tracker.Config{}, tracker.ProgressMap{}, nil
@@ -151,14 +149,14 @@
 	return checkAndReturn(cfg, prs)
 }
 
-// apply a ConfChange to the configuration. By convention, changes to voters are
+// apply a change to the configuration. By convention, changes to voters are
 // always made to the incoming majority config Voters[0]. Voters[1] is either
 // empty or preserves the outgoing majority configuration while in a joint state.
-func (c Changer) apply(cfg *tracker.Config, prs tracker.ProgressMap, ccs ...pb.ConfChange) error {
+func (c Changer) apply(cfg *tracker.Config, prs tracker.ProgressMap, ccs ...pb.ConfChangeSingle) error {
 	for _, cc := range ccs {
 		if cc.NodeID == 0 {
 			// etcd replaces the NodeID with zero if it decides (downstream of
-			// raft) to not apply a ConfChange, so we have to have explicit code
+			// raft) to not apply a change, so we have to have explicit code
 			// here to ignore these.
 			continue
 		}
@@ -259,11 +257,15 @@
 		nilAwareAdd(&cfg.Learners, id)
 	}
 	prs[id] = &tracker.Progress{
-		// We initialize Progress.Next with lastIndex+1 so that the peer will be
-		// probed without an index first.
+		// Initializing the Progress with the last index means that the follower
+		// can be probed (with the last index).
 		//
-		// TODO(tbg): verify that, this is just my best guess.
-		Next:      c.LastIndex + 1,
+		// TODO(tbg): seems awfully optimistic. Using the first index would be
+		// better. The general expectation here is that the follower has no log
+		// at all (and will thus likely need a snapshot), though the app may
+		// have applied a snapshot out of band before adding the replica (thus
+		// making the first index the better choice).
+		Next:      c.LastIndex,
 		Match:     0,
 		Inflights: tracker.NewInflights(c.Tracker.MaxInflight),
 		IsLearner: isLearner,
@@ -327,6 +329,9 @@
 		if cfg.LearnersNext != nil {
 			return fmt.Errorf("LearnersNext must be nil when not joint")
 		}
+		if cfg.AutoLeave {
+			return fmt.Errorf("AutoLeave must be false when not joint")
+		}
 	}
 
 	return nil
@@ -408,7 +413,7 @@
 
 // Describe prints the type and NodeID of the configuration changes as a
 // space-delimited string.
-func Describe(ccs ...pb.ConfChange) string {
+func Describe(ccs ...pb.ConfChangeSingle) string {
 	var buf strings.Builder
 	for _, cc := range ccs {
 		if buf.Len() > 0 {
diff --git a/vendor/go.etcd.io/etcd/raft/confchange/restore.go b/vendor/go.etcd.io/etcd/raft/confchange/restore.go
new file mode 100644
index 0000000..724068d
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/confchange/restore.go
@@ -0,0 +1,155 @@
+// 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 confchange
+
+import (
+	pb "go.etcd.io/etcd/raft/raftpb"
+	"go.etcd.io/etcd/raft/tracker"
+)
+
+// toConfChangeSingle translates a conf state into 1) a slice of operations creating
+// first the config that will become the outgoing one, and then the incoming one, and
+// b) another slice that, when applied to the config resulted from 1), represents the
+// ConfState.
+func toConfChangeSingle(cs pb.ConfState) (out []pb.ConfChangeSingle, in []pb.ConfChangeSingle) {
+	// Example to follow along this code:
+	// voters=(1 2 3) learners=(5) outgoing=(1 2 4 6) learners_next=(4)
+	//
+	// This means that before entering the joint config, the configuration
+	// had voters (1 2 4) and perhaps some learners that are already gone.
+	// The new set of voters is (1 2 3), i.e. (1 2) were kept around, and (4 6)
+	// are no longer voters; however 4 is poised to become a learner upon leaving
+	// the joint state.
+	// We can't tell whether 5 was a learner before entering the joint config,
+	// but it doesn't matter (we'll pretend that it wasn't).
+	//
+	// The code below will construct
+	// outgoing = add 1; add 2; add 4; add 6
+	// incoming = remove 1; remove 2; remove 4; remove 6
+	//            add 1;    add 2;    add 3;
+	//            add-learner 5;
+	//            add-learner 4;
+	//
+	// So, when starting with an empty config, after applying 'outgoing' we have
+	//
+	//   quorum=(1 2 4 6)
+	//
+	// From which we enter a joint state via 'incoming'
+	//
+	//   quorum=(1 2 3)&&(1 2 4 6) learners=(5) learners_next=(4)
+	//
+	// as desired.
+
+	for _, id := range cs.VotersOutgoing {
+		// If there are outgoing voters, first add them one by one so that the
+		// (non-joint) config has them all.
+		out = append(out, pb.ConfChangeSingle{
+			Type:   pb.ConfChangeAddNode,
+			NodeID: id,
+		})
+
+	}
+
+	// We're done constructing the outgoing slice, now on to the incoming one
+	// (which will apply on top of the config created by the outgoing slice).
+
+	// First, we'll remove all of the outgoing voters.
+	for _, id := range cs.VotersOutgoing {
+		in = append(in, pb.ConfChangeSingle{
+			Type:   pb.ConfChangeRemoveNode,
+			NodeID: id,
+		})
+	}
+	// Then we'll add the incoming voters and learners.
+	for _, id := range cs.Voters {
+		in = append(in, pb.ConfChangeSingle{
+			Type:   pb.ConfChangeAddNode,
+			NodeID: id,
+		})
+	}
+	for _, id := range cs.Learners {
+		in = append(in, pb.ConfChangeSingle{
+			Type:   pb.ConfChangeAddLearnerNode,
+			NodeID: id,
+		})
+	}
+	// Same for LearnersNext; these are nodes we want to be learners but which
+	// are currently voters in the outgoing config.
+	for _, id := range cs.LearnersNext {
+		in = append(in, pb.ConfChangeSingle{
+			Type:   pb.ConfChangeAddLearnerNode,
+			NodeID: id,
+		})
+	}
+	return out, in
+}
+
+func chain(chg Changer, ops ...func(Changer) (tracker.Config, tracker.ProgressMap, error)) (tracker.Config, tracker.ProgressMap, error) {
+	for _, op := range ops {
+		cfg, prs, err := op(chg)
+		if err != nil {
+			return tracker.Config{}, nil, err
+		}
+		chg.Tracker.Config = cfg
+		chg.Tracker.Progress = prs
+	}
+	return chg.Tracker.Config, chg.Tracker.Progress, nil
+}
+
+// Restore takes a Changer (which must represent an empty configuration), and
+// runs a sequence of changes enacting the configuration described in the
+// ConfState.
+//
+// TODO(tbg) it's silly that this takes a Changer. Unravel this by making sure
+// the Changer only needs a ProgressMap (not a whole Tracker) at which point
+// this can just take LastIndex and MaxInflight directly instead and cook up
+// the results from that alone.
+func Restore(chg Changer, cs pb.ConfState) (tracker.Config, tracker.ProgressMap, error) {
+	outgoing, incoming := toConfChangeSingle(cs)
+
+	var ops []func(Changer) (tracker.Config, tracker.ProgressMap, error)
+
+	if len(outgoing) == 0 {
+		// No outgoing config, so just apply the incoming changes one by one.
+		for _, cc := range incoming {
+			cc := cc // loop-local copy
+			ops = append(ops, func(chg Changer) (tracker.Config, tracker.ProgressMap, error) {
+				return chg.Simple(cc)
+			})
+		}
+	} else {
+		// The ConfState describes a joint configuration.
+		//
+		// First, apply all of the changes of the outgoing config one by one, so
+		// that it temporarily becomes the incoming active config. For example,
+		// if the config is (1 2 3)&(2 3 4), this will establish (2 3 4)&().
+		for _, cc := range outgoing {
+			cc := cc // loop-local copy
+			ops = append(ops, func(chg Changer) (tracker.Config, tracker.ProgressMap, error) {
+				return chg.Simple(cc)
+			})
+		}
+		// Now enter the joint state, which rotates the above additions into the
+		// outgoing config, and adds the incoming config in. Continuing the
+		// example above, we'd get (1 2 3)&(2 3 4), i.e. the incoming operations
+		// would be removing 2,3,4 and then adding in 1,2,3 while transitioning
+		// into a joint state.
+		ops = append(ops, func(chg Changer) (tracker.Config, tracker.ProgressMap, error) {
+			return chg.EnterJoint(cs.AutoLeave, incoming...)
+		})
+	}
+
+	return chain(chg, ops...)
+}
diff --git a/vendor/go.etcd.io/etcd/raft/log_unstable.go b/vendor/go.etcd.io/etcd/raft/log_unstable.go
index 1005bf6..1bff5a7 100644
--- a/vendor/go.etcd.io/etcd/raft/log_unstable.go
+++ b/vendor/go.etcd.io/etcd/raft/log_unstable.go
@@ -55,10 +55,7 @@
 // is any.
 func (u *unstable) maybeTerm(i uint64) (uint64, bool) {
 	if i < u.offset {
-		if u.snapshot == nil {
-			return 0, false
-		}
-		if u.snapshot.Metadata.Index == i {
+		if u.snapshot != nil && u.snapshot.Metadata.Index == i {
 			return u.snapshot.Metadata.Term, true
 		}
 		return 0, false
@@ -71,6 +68,7 @@
 	if i > last {
 		return 0, false
 	}
+
 	return u.entries[i-u.offset].Term, true
 }
 
diff --git a/vendor/go.etcd.io/etcd/raft/logger.go b/vendor/go.etcd.io/etcd/raft/logger.go
index 426a77d..6d89629 100644
--- a/vendor/go.etcd.io/etcd/raft/logger.go
+++ b/vendor/go.etcd.io/etcd/raft/logger.go
@@ -19,6 +19,7 @@
 	"io/ioutil"
 	"log"
 	"os"
+	"sync"
 )
 
 type Logger interface {
@@ -41,11 +42,16 @@
 	Panicf(format string, v ...interface{})
 }
 
-func SetLogger(l Logger) { raftLogger = l }
+func SetLogger(l Logger) {
+	raftLoggerMu.Lock()
+	raftLogger = l
+	raftLoggerMu.Unlock()
+}
 
 var (
 	defaultLogger = &DefaultLogger{Logger: log.New(os.Stderr, "raft", log.LstdFlags)}
 	discardLogger = &DefaultLogger{Logger: log.New(ioutil.Discard, "", 0)}
+	raftLoggerMu  sync.Mutex
 	raftLogger    = Logger(defaultLogger)
 )
 
diff --git a/vendor/go.etcd.io/etcd/raft/node.go b/vendor/go.etcd.io/etcd/raft/node.go
index 4a3b2f1..ab6185b 100644
--- a/vendor/go.etcd.io/etcd/raft/node.go
+++ b/vendor/go.etcd.io/etcd/raft/node.go
@@ -132,10 +132,20 @@
 	// Propose proposes that data be appended to the log. Note that proposals can be lost without
 	// notice, therefore it is user's job to ensure proposal retries.
 	Propose(ctx context.Context, data []byte) error
-	// ProposeConfChange proposes config change.
-	// At most one ConfChange can be in the process of going through consensus.
-	// Application needs to call ApplyConfChange when applying EntryConfChange type entry.
-	ProposeConfChange(ctx context.Context, cc pb.ConfChange) error
+	// ProposeConfChange proposes a configuration change. Like any proposal, the
+	// configuration change may be dropped with or without an error being
+	// returned. In particular, configuration changes are dropped unless the
+	// leader has certainty that there is no prior unapplied configuration
+	// change in its log.
+	//
+	// The method accepts either a pb.ConfChange (deprecated) or pb.ConfChangeV2
+	// message. The latter allows arbitrary configuration changes via joint
+	// consensus, notably including replacing a voter. Passing a ConfChangeV2
+	// message is only allowed if all Nodes participating in the cluster run a
+	// version of this library aware of the V2 API. See pb.ConfChangeV2 for
+	// usage details and semantics.
+	ProposeConfChange(ctx context.Context, cc pb.ConfChangeI) error
+
 	// Step advances the state machine using the given message. ctx.Err() will be returned, if any.
 	Step(ctx context.Context, msg pb.Message) error
 
@@ -156,11 +166,13 @@
 	// a long time to apply the snapshot data. To continue receiving Ready without blocking raft
 	// progress, it can call Advance before finishing applying the last ready.
 	Advance()
-	// ApplyConfChange applies config change to the local node.
-	// Returns an opaque ConfState protobuf which must be recorded
-	// in snapshots. Will never return nil; it returns a pointer only
-	// to match MemoryStorage.Compact.
-	ApplyConfChange(cc pb.ConfChange) *pb.ConfState
+	// ApplyConfChange applies a config change (previously passed to
+	// ProposeConfChange) to the node. This must be called whenever a config
+	// change is observed in Ready.CommittedEntries.
+	//
+	// Returns an opaque non-nil ConfState protobuf which must be recorded in
+	// snapshots.
+	ApplyConfChange(cc pb.ConfChangeI) *pb.ConfState
 
 	// TransferLeadership attempts to transfer leadership to the given transferee.
 	TransferLeadership(ctx context.Context, lead, transferee uint64)
@@ -197,52 +209,21 @@
 
 // StartNode returns a new Node given configuration and a list of raft peers.
 // It appends a ConfChangeAddNode entry for each given peer to the initial log.
+//
+// Peers must not be zero length; call RestartNode in that case.
 func StartNode(c *Config, peers []Peer) Node {
-	r := newRaft(c)
-	// become the follower at term 1 and apply initial configuration
-	// entries of term 1
-	r.becomeFollower(1, None)
-	for _, peer := range peers {
-		cc := pb.ConfChange{Type: pb.ConfChangeAddNode, NodeID: peer.ID, Context: peer.Context}
-		d, err := cc.Marshal()
-		if err != nil {
-			panic("unexpected marshal error")
-		}
-		// TODO(tbg): this should append the ConfChange for the own node first
-		// and also call applyConfChange below for that node first. Otherwise
-		// we have a Raft group (for a little while) that doesn't have itself
-		// in its config, which is bad.
-		// This whole way of setting things up is rickety. The app should just
-		// populate the initial ConfState appropriately and then all of this
-		// goes away.
-		e := pb.Entry{
-			Type:  pb.EntryConfChange,
-			Term:  1,
-			Index: r.raftLog.lastIndex() + 1,
-			Data:  d,
-		}
-		r.raftLog.append(e)
+	if len(peers) == 0 {
+		panic("no peers given; use RestartNode instead")
 	}
-	// Mark these initial entries as committed.
-	// TODO(bdarnell): These entries are still unstable; do we need to preserve
-	// the invariant that committed < unstable?
-	r.raftLog.committed = r.raftLog.lastIndex()
-	// Now apply them, mainly so that the application can call Campaign
-	// immediately after StartNode in tests. Note that these nodes will
-	// be added to raft twice: here and when the application's Ready
-	// loop calls ApplyConfChange. The calls to addNode must come after
-	// all calls to raftLog.append so progress.next is set after these
-	// bootstrapping entries (it is an error if we try to append these
-	// entries since they have already been committed).
-	// We do not set raftLog.applied so the application will be able
-	// to observe all conf changes via Ready.CommittedEntries.
-	for _, peer := range peers {
-		r.applyConfChange(pb.ConfChange{NodeID: peer.ID, Type: pb.ConfChangeAddNode})
+	rn, err := NewRawNode(c)
+	if err != nil {
+		panic(err)
 	}
+	rn.Bootstrap(peers)
 
-	n := newNode()
-	n.logger = c.Logger
-	go n.run(r)
+	n := newNode(rn)
+
+	go n.run()
 	return &n
 }
 
@@ -251,11 +232,12 @@
 // If the caller has an existing state machine, pass in the last log index that
 // has been applied to it; otherwise use zero.
 func RestartNode(c *Config) Node {
-	r := newRaft(c)
-
-	n := newNode()
-	n.logger = c.Logger
-	go n.run(r)
+	rn, err := NewRawNode(c)
+	if err != nil {
+		panic(err)
+	}
+	n := newNode(rn)
+	go n.run()
 	return &n
 }
 
@@ -268,7 +250,7 @@
 type node struct {
 	propc      chan msgWithResult
 	recvc      chan pb.Message
-	confc      chan pb.ConfChange
+	confc      chan pb.ConfChangeV2
 	confstatec chan pb.ConfState
 	readyc     chan Ready
 	advancec   chan struct{}
@@ -277,14 +259,14 @@
 	stop       chan struct{}
 	status     chan chan Status
 
-	logger Logger
+	rn *RawNode
 }
 
-func newNode() node {
+func newNode(rn *RawNode) node {
 	return node{
 		propc:      make(chan msgWithResult),
 		recvc:      make(chan pb.Message),
-		confc:      make(chan pb.ConfChange),
+		confc:      make(chan pb.ConfChangeV2),
 		confstatec: make(chan pb.ConfState),
 		readyc:     make(chan Ready),
 		advancec:   make(chan struct{}),
@@ -295,6 +277,7 @@
 		done:   make(chan struct{}),
 		stop:   make(chan struct{}),
 		status: make(chan chan Status),
+		rn:     rn,
 	}
 }
 
@@ -310,30 +293,30 @@
 	<-n.done
 }
 
-func (n *node) run(r *raft) {
+func (n *node) run() {
 	var propc chan msgWithResult
 	var readyc chan Ready
 	var advancec chan struct{}
-	var prevLastUnstablei, prevLastUnstablet uint64
-	var havePrevLastUnstablei bool
-	var prevSnapi uint64
-	var applyingToI uint64
 	var rd Ready
 
+	r := n.rn.raft
+
 	lead := None
-	prevSoftSt := r.softState()
-	prevHardSt := emptyState
 
 	for {
 		if advancec != nil {
 			readyc = nil
-		} else {
-			rd = newReady(r, prevSoftSt, prevHardSt)
-			if rd.containsUpdates() {
-				readyc = n.readyc
-			} else {
-				readyc = nil
-			}
+		} else if n.rn.HasReady() {
+			// Populate a Ready. Note that this Ready is not guaranteed to
+			// actually be handled. We will arm readyc, but there's no guarantee
+			// that we will actually send on it. It's possible that we will
+			// service another channel instead, loop around, and then populate
+			// the Ready again. We could instead force the previous Ready to be
+			// handled first, but it's generally good to emit larger Readys plus
+			// it simplifies testing (by emitting less frequently and more
+			// predictably).
+			rd = n.rn.readyWithoutAccept()
+			readyc = n.readyc
 		}
 
 		if lead != r.lead {
@@ -369,11 +352,27 @@
 				r.Step(m)
 			}
 		case cc := <-n.confc:
+			_, okBefore := r.prs.Progress[r.id]
 			cs := r.applyConfChange(cc)
-			if _, ok := r.prs.Progress[r.id]; !ok {
-				// block incoming proposal when local node is
-				// removed
-				if cc.NodeID == r.id {
+			// If the node was removed, block incoming proposals. Note that we
+			// only do this if the node was in the config before. Nodes may be
+			// a member of the group without knowing this (when they're catching
+			// up on the log and don't have the latest config) and we don't want
+			// to block the proposal channel in that case.
+			//
+			// NB: propc is reset when the leader changes, which, if we learn
+			// about it, sort of implies that we got readded, maybe? This isn't
+			// very sound and likely has bugs.
+			if _, okAfter := r.prs.Progress[r.id]; okBefore && !okAfter {
+				var found bool
+				for _, sl := range [][]uint64{cs.Voters, cs.VotersOutgoing} {
+					for _, id := range sl {
+						if id == r.id {
+							found = true
+						}
+					}
+				}
+				if !found {
 					propc = nil
 				}
 			}
@@ -382,40 +381,13 @@
 			case <-n.done:
 			}
 		case <-n.tickc:
-			r.tick()
+			n.rn.Tick()
 		case readyc <- rd:
-			if rd.SoftState != nil {
-				prevSoftSt = rd.SoftState
-			}
-			if len(rd.Entries) > 0 {
-				prevLastUnstablei = rd.Entries[len(rd.Entries)-1].Index
-				prevLastUnstablet = rd.Entries[len(rd.Entries)-1].Term
-				havePrevLastUnstablei = true
-			}
-			if !IsEmptyHardState(rd.HardState) {
-				prevHardSt = rd.HardState
-			}
-			if !IsEmptySnap(rd.Snapshot) {
-				prevSnapi = rd.Snapshot.Metadata.Index
-			}
-			if index := rd.appliedCursor(); index != 0 {
-				applyingToI = index
-			}
-
-			r.msgs = nil
-			r.readStates = nil
-			r.reduceUncommittedSize(rd.CommittedEntries)
+			n.rn.acceptReady(rd)
 			advancec = n.advancec
 		case <-advancec:
-			if applyingToI != 0 {
-				r.raftLog.appliedTo(applyingToI)
-				applyingToI = 0
-			}
-			if havePrevLastUnstablei {
-				r.raftLog.stableTo(prevLastUnstablei, prevLastUnstablet)
-				havePrevLastUnstablei = false
-			}
-			r.raftLog.stableSnapTo(prevSnapi)
+			n.rn.Advance(rd)
+			rd = Ready{}
 			advancec = nil
 		case c := <-n.status:
 			c <- getStatus(r)
@@ -433,7 +405,7 @@
 	case n.tickc <- struct{}{}:
 	case <-n.done:
 	default:
-		n.logger.Warningf("A tick missed to fire. Node blocks too long!")
+		n.rn.raft.logger.Warningf("%x (leader %v) A tick missed to fire. Node blocks too long!", n.rn.raft.id, n.rn.raft.id == n.rn.raft.lead)
 	}
 }
 
@@ -452,12 +424,20 @@
 	return n.step(ctx, m)
 }
 
-func (n *node) ProposeConfChange(ctx context.Context, cc pb.ConfChange) error {
-	data, err := cc.Marshal()
+func confChangeToMsg(c pb.ConfChangeI) (pb.Message, error) {
+	typ, data, err := pb.MarshalConfChange(c)
+	if err != nil {
+		return pb.Message{}, err
+	}
+	return pb.Message{Type: pb.MsgProp, Entries: []pb.Entry{{Type: typ, Data: data}}}, nil
+}
+
+func (n *node) ProposeConfChange(ctx context.Context, cc pb.ConfChangeI) error {
+	msg, err := confChangeToMsg(cc)
 	if err != nil {
 		return err
 	}
-	return n.Step(ctx, pb.Message{Type: pb.MsgProp, Entries: []pb.Entry{{Type: pb.EntryConfChange, Data: data}}})
+	return n.Step(ctx, msg)
 }
 
 func (n *node) step(ctx context.Context, m pb.Message) error {
@@ -518,10 +498,10 @@
 	}
 }
 
-func (n *node) ApplyConfChange(cc pb.ConfChange) *pb.ConfState {
+func (n *node) ApplyConfChange(cc pb.ConfChangeI) *pb.ConfState {
 	var cs pb.ConfState
 	select {
-	case n.confc <- cc:
+	case n.confc <- cc.AsV2():
 	case <-n.done:
 	}
 	select {
diff --git a/vendor/go.etcd.io/etcd/raft/quorum/majority.go b/vendor/go.etcd.io/etcd/raft/quorum/majority.go
index 5eba503..8858a36 100644
--- a/vendor/go.etcd.io/etcd/raft/quorum/majority.go
+++ b/vendor/go.etcd.io/etcd/raft/quorum/majority.go
@@ -102,9 +102,17 @@
 	return buf.String()
 }
 
-type uint64Slice []uint64
+// Slice returns the MajorityConfig as a sorted slice.
+func (c MajorityConfig) Slice() []uint64 {
+	var sl []uint64
+	for id := range c {
+		sl = append(sl, id)
+	}
+	sort.Slice(sl, func(i, j int) bool { return sl[i] < sl[j] })
+	return sl
+}
 
-func insertionSort(sl uint64Slice) {
+func insertionSort(sl []uint64) {
 	a, b := 0, len(sl)
 	for i := a + 1; i < b; i++ {
 		for j := i; j > a && sl[j] < sl[j-1]; j-- {
@@ -131,12 +139,12 @@
 	// performance is a lesser concern (additionally the performance
 	// implications of an allocation here are far from drastic).
 	var stk [7]uint64
-	srt := uint64Slice(stk[:])
-
-	if cap(srt) < n {
+	var srt []uint64
+	if len(stk) >= n {
+		srt = stk[:n]
+	} else {
 		srt = make([]uint64, n)
 	}
-	srt = srt[:n]
 
 	{
 		// Fill the slice with the indexes observed. Any unused slots will be
diff --git a/vendor/go.etcd.io/etcd/raft/raft.go b/vendor/go.etcd.io/etcd/raft/raft.go
index 01e23ec..cdcb43d 100644
--- a/vendor/go.etcd.io/etcd/raft/raft.go
+++ b/vendor/go.etcd.io/etcd/raft/raft.go
@@ -20,6 +20,7 @@
 	"fmt"
 	"math"
 	"math/rand"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -263,7 +264,8 @@
 
 	maxMsgSize         uint64
 	maxUncommittedSize uint64
-	prs                tracker.ProgressTracker
+	// TODO(tbg): rename to trk.
+	prs tracker.ProgressTracker
 
 	state StateType
 
@@ -327,18 +329,18 @@
 	if err != nil {
 		panic(err) // TODO(bdarnell)
 	}
-	peers := c.peers
-	learners := c.learners
-	if len(cs.Nodes) > 0 || len(cs.Learners) > 0 {
-		if len(peers) > 0 || len(learners) > 0 {
+
+	if len(c.peers) > 0 || len(c.learners) > 0 {
+		if len(cs.Voters) > 0 || len(cs.Learners) > 0 {
 			// TODO(bdarnell): the peers argument is always nil except in
 			// tests; the argument should be removed and these tests should be
 			// updated to specify their nodes through a snapshot.
-			panic("cannot specify both newRaft(peers, learners) and ConfState.(Nodes, Learners)")
+			panic("cannot specify both newRaft(peers, learners) and ConfState.(Voters, Learners)")
 		}
-		peers = cs.Nodes
-		learners = cs.Learners
+		cs.Voters = c.peers
+		cs.Learners = c.learners
 	}
+
 	r := &raft{
 		id:                        c.ID,
 		lead:                      None,
@@ -355,16 +357,17 @@
 		readOnly:                  newReadOnly(c.ReadOnlyOption),
 		disableProposalForwarding: c.DisableProposalForwarding,
 	}
-	for _, p := range peers {
-		// Add node to active config.
-		r.applyConfChange(pb.ConfChange{Type: pb.ConfChangeAddNode, NodeID: p})
-	}
-	for _, p := range learners {
-		// Add learner to active config.
-		r.applyConfChange(pb.ConfChange{Type: pb.ConfChangeAddLearnerNode, NodeID: p})
-	}
 
-	if !isHardStateEqual(hs, emptyState) {
+	cfg, prs, err := confchange.Restore(confchange.Changer{
+		Tracker:   r.prs,
+		LastIndex: raftlog.lastIndex(),
+	}, cs)
+	if err != nil {
+		panic(err)
+	}
+	assertConfStatesEquivalent(r.logger, cs, r.switchToConfig(cfg, prs))
+
+	if !IsEmptyHardState(hs) {
 		r.loadState(hs)
 	}
 	if c.Applied > 0 {
@@ -527,7 +530,6 @@
 		if id == r.id {
 			return
 		}
-
 		r.sendAppend(id)
 	})
 }
@@ -551,6 +553,46 @@
 	})
 }
 
+func (r *raft) advance(rd Ready) {
+	// If entries were applied (or a snapshot), update our cursor for
+	// the next Ready. Note that if the current HardState contains a
+	// new Commit index, this does not mean that we're also applying
+	// all of the new entries due to commit pagination by size.
+	if index := rd.appliedCursor(); index > 0 {
+		r.raftLog.appliedTo(index)
+		if r.prs.Config.AutoLeave && index >= r.pendingConfIndex && r.state == StateLeader {
+			// If the current (and most recent, at least for this leader's term)
+			// configuration should be auto-left, initiate that now.
+			ccdata, err := (&pb.ConfChangeV2{}).Marshal()
+			if err != nil {
+				panic(err)
+			}
+			ent := pb.Entry{
+				Type: pb.EntryConfChangeV2,
+				Data: ccdata,
+			}
+			if !r.appendEntry(ent) {
+				// If we could not append the entry, bump the pending conf index
+				// so that we'll try again later.
+				//
+				// TODO(tbg): test this case.
+				r.pendingConfIndex = r.raftLog.lastIndex()
+			} else {
+				r.logger.Infof("initiating automatic transition out of joint configuration %s", r.prs.Config)
+			}
+		}
+	}
+	r.reduceUncommittedSize(rd.CommittedEntries)
+
+	if len(rd.Entries) > 0 {
+		e := rd.Entries[len(rd.Entries)-1]
+		r.raftLog.stableTo(e.Index, e.Term)
+	}
+	if !IsEmptySnap(rd.Snapshot) {
+		r.raftLog.stableSnapTo(rd.Snapshot.Metadata.Index)
+	}
+}
+
 // maybeCommit attempts to advance the commit index. Returns true if
 // the commit index changed (in which case the caller should call
 // r.bcastAppend).
@@ -753,7 +795,16 @@
 		}
 		return
 	}
-	for id := range r.prs.Voters.IDs() {
+	var ids []uint64
+	{
+		idMap := r.prs.Voters.IDs()
+		ids = make([]uint64, 0, len(idMap))
+		for id := range idMap {
+			ids = append(ids, id)
+		}
+		sort.Slice(ids, func(i, j int) bool { return ids[i] < ids[j] })
+	}
+	for _, id := range ids {
 		if id == r.id {
 			continue
 		}
@@ -880,12 +931,6 @@
 		}
 
 	case pb.MsgVote, pb.MsgPreVote:
-		if r.isLearner {
-			// TODO: learner may need to vote, in case of node down when confchange.
-			r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] ignored %s from %x [logterm: %d, index: %d] at term %d: learner can not vote",
-				r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term)
-			return nil
-		}
 		// We can vote if this is a repeat of a vote we've already cast...
 		canVote := r.Vote == m.From ||
 			// ...we haven't voted and we don't think there's a leader yet in this term...
@@ -894,6 +939,24 @@
 			(m.Type == pb.MsgPreVote && m.Term > r.Term)
 		// ...and we believe the candidate is up to date.
 		if canVote && r.raftLog.isUpToDate(m.Index, m.LogTerm) {
+			// Note: it turns out that that learners must be allowed to cast votes.
+			// This seems counter- intuitive but is necessary in the situation in which
+			// a learner has been promoted (i.e. is now a voter) but has not learned
+			// about this yet.
+			// For example, consider a group in which id=1 is a learner and id=2 and
+			// id=3 are voters. A configuration change promoting 1 can be committed on
+			// the quorum `{2,3}` without the config change being appended to the
+			// learner's log. If the leader (say 2) fails, there are de facto two
+			// voters remaining. Only 3 can win an election (due to its log containing
+			// all committed entries), but to do so it will need 1 to vote. But 1
+			// considers itself a learner and will continue to do so until 3 has
+			// stepped up as leader, replicates the conf change to 1, and 1 applies it.
+			// Ultimately, by receiving a request to vote, the learner realizes that
+			// the candidate believes it to be a voter, and that it should act
+			// accordingly. The candidate's config may be stale, too; but in that case
+			// it won't win the election, at least in the absence of the bug discussed
+			// in:
+			// https://github.com/etcd-io/etcd/issues/7625#issuecomment-488798263.
 			r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] cast %s for %x [logterm: %d, index: %d] at term %d",
 				r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term)
 			// When responding to Msg{Pre,}Vote messages we include the term
@@ -973,10 +1036,36 @@
 
 		for i := range m.Entries {
 			e := &m.Entries[i]
+			var cc pb.ConfChangeI
 			if e.Type == pb.EntryConfChange {
-				if r.pendingConfIndex > r.raftLog.applied {
-					r.logger.Infof("propose conf %s ignored since pending unapplied configuration [index %d, applied %d]",
-						e, r.pendingConfIndex, r.raftLog.applied)
+				var ccc pb.ConfChange
+				if err := ccc.Unmarshal(e.Data); err != nil {
+					panic(err)
+				}
+				cc = ccc
+			} else if e.Type == pb.EntryConfChangeV2 {
+				var ccc pb.ConfChangeV2
+				if err := ccc.Unmarshal(e.Data); err != nil {
+					panic(err)
+				}
+				cc = ccc
+			}
+			if cc != nil {
+				alreadyPending := r.pendingConfIndex > r.raftLog.applied
+				alreadyJoint := len(r.prs.Config.Voters[1]) > 0
+				wantsLeaveJoint := len(cc.AsV2().Changes) == 0
+
+				var refused string
+				if alreadyPending {
+					refused = fmt.Sprintf("possible unapplied conf change at index %d (applied to %d)", r.pendingConfIndex, r.raftLog.applied)
+				} else if alreadyJoint && !wantsLeaveJoint {
+					refused = "must transition out of joint config first"
+				} else if !alreadyJoint && wantsLeaveJoint {
+					refused = "not in joint state; refusing empty conf change"
+				}
+
+				if refused != "" {
+					r.logger.Infof("%x ignoring conf change %v at config %s: %s", r.id, cc, r.prs.Config, refused)
 					m.Entries[i] = pb.Entry{Type: pb.EntryNormal}
 				} else {
 					r.pendingConfIndex = r.raftLog.lastIndex() + uint64(i) + 1
@@ -1010,7 +1099,7 @@
 			case ReadOnlyLeaseBased:
 				ri := r.raftLog.committed
 				if m.From == None || m.From == r.id { // from local member
-					r.readStates = append(r.readStates, ReadState{Index: r.raftLog.committed, RequestCtx: m.Entries[0].Data})
+					r.readStates = append(r.readStates, ReadState{Index: ri, RequestCtx: m.Entries[0].Data})
 				} else {
 					r.send(pb.Message{To: m.From, Type: pb.MsgReadIndexResp, Index: ri, Entries: m.Entries})
 				}
@@ -1037,7 +1126,7 @@
 		pr.RecentActive = true
 
 		if m.Reject {
-			r.logger.Debugf("%x received msgApp rejection(lastindex: %d) from %x for index %d",
+			r.logger.Debugf("%x received MsgAppResp(MsgApp was rejected, lastindex: %d) from %x for index %d",
 				r.id, m.RejectHint, m.From, m.Index)
 			if pr.MaybeDecrTo(m.Index, m.RejectHint) {
 				r.logger.Debugf("%x decreased progress of %x to [%s]", r.id, m.From, pr)
@@ -1053,6 +1142,9 @@
 				case pr.State == tracker.StateProbe:
 					pr.BecomeReplicate()
 				case pr.State == tracker.StateSnapshot && pr.Match >= pr.PendingSnapshot:
+					// TODO(tbg): we should also enter this branch if a snapshot is
+					// received that is below pr.PendingSnapshot but which makes it
+					// possible to use the log again.
 					r.logger.Debugf("%x recovered from needing snapshot, resumed sending replication messages to %x [%s]", r.id, m.From, pr)
 					// Transition back to replicating state via probing state
 					// (which takes the snapshot into account). If we didn't
@@ -1134,8 +1226,8 @@
 			pr.BecomeProbe()
 			r.logger.Debugf("%x snapshot failed, resumed sending replication messages to %x [%s]", r.id, m.From, pr)
 		}
-		// If snapshot finish, wait for the msgAppResp from the remote node before sending
-		// out the next msgApp.
+		// If snapshot finish, wait for the MsgAppResp from the remote node before sending
+		// out the next MsgApp.
 		// If snapshot failure, wait for a heartbeat interval before next try
 		pr.ProbeSent = true
 	case pb.MsgUnreachable:
@@ -1294,7 +1386,7 @@
 	if mlastIndex, ok := r.raftLog.maybeAppend(m.Index, m.LogTerm, m.Commit, m.Entries...); ok {
 		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: mlastIndex})
 	} else {
-		r.logger.Debugf("%x [logterm: %d, index: %d] rejected msgApp [logterm: %d, index: %d] from %x",
+		r.logger.Debugf("%x [logterm: %d, index: %d] rejected MsgApp [logterm: %d, index: %d] from %x",
 			r.id, r.raftLog.zeroTermOnErrCompacted(r.raftLog.term(m.Index)), m.Index, m.LogTerm, m.Index, m.From)
 		r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: m.Index, Reject: true, RejectHint: r.raftLog.lastIndex()})
 	}
@@ -1339,12 +1431,12 @@
 	}
 
 	// More defense-in-depth: throw away snapshot if recipient is not in the
-	// config. This shouuldn't ever happen (at the time of writing) but lots of
+	// config. This shouldn't ever happen (at the time of writing) but lots of
 	// code here and there assumes that r.id is in the progress tracker.
 	found := false
 	cs := s.Metadata.ConfState
 	for _, set := range [][]uint64{
-		cs.Nodes,
+		cs.Voters,
 		cs.Learners,
 	} {
 		for _, id := range set {
@@ -1375,12 +1467,18 @@
 
 	// Reset the configuration and add the (potentially updated) peers in anew.
 	r.prs = tracker.MakeProgressTracker(r.prs.MaxInflight)
-	for _, id := range s.Metadata.ConfState.Nodes {
-		r.applyConfChange(pb.ConfChange{NodeID: id, Type: pb.ConfChangeAddNode})
+	cfg, prs, err := confchange.Restore(confchange.Changer{
+		Tracker:   r.prs,
+		LastIndex: r.raftLog.lastIndex(),
+	}, cs)
+
+	if err != nil {
+		// This should never happen. Either there's a bug in our config change
+		// handling or the client corrupted the conf change.
+		panic(fmt.Sprintf("unable to restore config %+v: %s", cs, err))
 	}
-	for _, id := range s.Metadata.ConfState.Learners {
-		r.applyConfChange(pb.ConfChange{NodeID: id, Type: pb.ConfChangeAddLearnerNode})
-	}
+
+	assertConfStatesEquivalent(r.logger, cs, r.switchToConfig(cfg, prs))
 
 	pr := r.prs.Progress[r.id]
 	pr.MaybeUpdate(pr.Next - 1) // TODO(tbg): this is untested and likely unneeded
@@ -1397,21 +1495,40 @@
 	return pr != nil && !pr.IsLearner
 }
 
-func (r *raft) applyConfChange(cc pb.ConfChange) pb.ConfState {
-	cfg, prs, err := confchange.Changer{
-		Tracker:   r.prs,
-		LastIndex: r.raftLog.lastIndex(),
-	}.Simple(cc)
+func (r *raft) applyConfChange(cc pb.ConfChangeV2) pb.ConfState {
+	cfg, prs, err := func() (tracker.Config, tracker.ProgressMap, error) {
+		changer := confchange.Changer{
+			Tracker:   r.prs,
+			LastIndex: r.raftLog.lastIndex(),
+		}
+		if cc.LeaveJoint() {
+			return changer.LeaveJoint()
+		} else if autoLeave, ok := cc.EnterJoint(); ok {
+			return changer.EnterJoint(autoLeave, cc.Changes...)
+		}
+		return changer.Simple(cc.Changes...)
+	}()
+
 	if err != nil {
+		// TODO(tbg): return the error to the caller.
 		panic(err)
 	}
+
+	return r.switchToConfig(cfg, prs)
+}
+
+// switchToConfig reconfigures this node to use the provided configuration. It
+// updates the in-memory state and, when necessary, carries out additional
+// actions such as reacting to the removal of nodes or changed quorum
+// requirements.
+//
+// The inputs usually result from restoring a ConfState or applying a ConfChange.
+func (r *raft) switchToConfig(cfg tracker.Config, prs tracker.ProgressMap) pb.ConfState {
 	r.prs.Config = cfg
 	r.prs.Progress = prs
 
 	r.logger.Infof("%x switched to configuration %s", r.id, r.prs.Config)
-	// Now that the configuration is updated, handle any side effects.
-
-	cs := pb.ConfState{Nodes: r.prs.VoterNodes(), Learners: r.prs.LearnerNodes()}
+	cs := r.prs.ConfState()
 	pr, ok := r.prs.Progress[r.id]
 
 	// Update whether the node itself is a learner, resetting to false when the
@@ -1433,13 +1550,21 @@
 
 	// The remaining steps only make sense if this node is the leader and there
 	// are other nodes.
-	if r.state != StateLeader || len(cs.Nodes) == 0 {
+	if r.state != StateLeader || len(cs.Voters) == 0 {
 		return cs
 	}
+
 	if r.maybeCommit() {
-		// The quorum size may have been reduced (but not to zero), so see if
-		// any pending entries can be committed.
+		// If the configuration change means that more entries are committed now,
+		// broadcast/append to everyone in the updated config.
 		r.bcastAppend()
+	} else {
+		// Otherwise, still probe the newly added replicas; there's no reason to
+		// let them wait out a heartbeat interval (or the next incoming
+		// proposal).
+		r.prs.Visit(func(id uint64, pr *tracker.Progress) {
+			r.maybeSendAppend(id, false /* sendIfEmpty */)
+		})
 	}
 	// If the the leadTransferee was removed, abort the leadership transfer.
 	if _, tOK := r.prs.Progress[r.leadTransferee]; !tOK && r.leadTransferee != 0 {
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()
+}
diff --git a/vendor/go.etcd.io/etcd/raft/raftpb/confstate.go b/vendor/go.etcd.io/etcd/raft/raftpb/confstate.go
new file mode 100644
index 0000000..4bda932
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/raftpb/confstate.go
@@ -0,0 +1,45 @@
+// 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"
+	"reflect"
+	"sort"
+)
+
+// Equivalent returns a nil error if the inputs describe the same configuration.
+// On mismatch, returns a descriptive error showing the differences.
+func (cs ConfState) Equivalent(cs2 ConfState) error {
+	cs1 := cs
+	orig1, orig2 := cs1, cs2
+	s := func(sl *[]uint64) {
+		*sl = append([]uint64(nil), *sl...)
+		sort.Slice(*sl, func(i, j int) bool { return (*sl)[i] < (*sl)[j] })
+	}
+
+	for _, cs := range []*ConfState{&cs1, &cs2} {
+		s(&cs.Voters)
+		s(&cs.Learners)
+		s(&cs.VotersOutgoing)
+		s(&cs.LearnersNext)
+		cs.XXX_unrecognized = nil
+	}
+
+	if !reflect.DeepEqual(cs1, cs2) {
+		return fmt.Errorf("ConfStates not equivalent after sorting:\n%+#v\n%+#v\nInputs were:\n%+#v\n%+#v", cs1, cs2, orig1, orig2)
+	}
+	return nil
+}
diff --git a/vendor/go.etcd.io/etcd/raft/raftpb/raft.pb.go b/vendor/go.etcd.io/etcd/raft/raftpb/raft.pb.go
index fd9ee37..fcf259c 100644
--- a/vendor/go.etcd.io/etcd/raft/raftpb/raft.pb.go
+++ b/vendor/go.etcd.io/etcd/raft/raftpb/raft.pb.go
@@ -15,6 +15,8 @@
 		HardState
 		ConfState
 		ConfChange
+		ConfChangeSingle
+		ConfChangeV2
 */
 package raftpb
 
@@ -44,17 +46,20 @@
 type EntryType int32
 
 const (
-	EntryNormal     EntryType = 0
-	EntryConfChange EntryType = 1
+	EntryNormal       EntryType = 0
+	EntryConfChange   EntryType = 1
+	EntryConfChangeV2 EntryType = 2
 )
 
 var EntryType_name = map[int32]string{
 	0: "EntryNormal",
 	1: "EntryConfChange",
+	2: "EntryConfChangeV2",
 }
 var EntryType_value = map[string]int32{
-	"EntryNormal":     0,
-	"EntryConfChange": 1,
+	"EntryNormal":       0,
+	"EntryConfChange":   1,
+	"EntryConfChangeV2": 2,
 }
 
 func (x EntryType) Enum() *EntryType {
@@ -160,6 +165,57 @@
 }
 func (MessageType) EnumDescriptor() ([]byte, []int) { return fileDescriptorRaft, []int{1} }
 
+// ConfChangeTransition specifies the behavior of a configuration change with
+// respect to joint consensus.
+type ConfChangeTransition int32
+
+const (
+	// Automatically use the simple protocol if possible, otherwise fall back
+	// to ConfChangeJointImplicit. Most applications will want to use this.
+	ConfChangeTransitionAuto ConfChangeTransition = 0
+	// Use joint consensus unconditionally, and transition out of them
+	// automatically (by proposing a zero configuration change).
+	//
+	// This option is suitable for applications that want to minimize the time
+	// spent in the joint configuration and do not store the joint configuration
+	// in the state machine (outside of InitialState).
+	ConfChangeTransitionJointImplicit ConfChangeTransition = 1
+	// Use joint consensus and remain in the joint configuration until the
+	// application proposes a no-op configuration change. This is suitable for
+	// applications that want to explicitly control the transitions, for example
+	// to use a custom payload (via the Context field).
+	ConfChangeTransitionJointExplicit ConfChangeTransition = 2
+)
+
+var ConfChangeTransition_name = map[int32]string{
+	0: "ConfChangeTransitionAuto",
+	1: "ConfChangeTransitionJointImplicit",
+	2: "ConfChangeTransitionJointExplicit",
+}
+var ConfChangeTransition_value = map[string]int32{
+	"ConfChangeTransitionAuto":          0,
+	"ConfChangeTransitionJointImplicit": 1,
+	"ConfChangeTransitionJointExplicit": 2,
+}
+
+func (x ConfChangeTransition) Enum() *ConfChangeTransition {
+	p := new(ConfChangeTransition)
+	*p = x
+	return p
+}
+func (x ConfChangeTransition) String() string {
+	return proto.EnumName(ConfChangeTransition_name, int32(x))
+}
+func (x *ConfChangeTransition) UnmarshalJSON(data []byte) error {
+	value, err := proto.UnmarshalJSONEnum(ConfChangeTransition_value, data, "ConfChangeTransition")
+	if err != nil {
+		return err
+	}
+	*x = ConfChangeTransition(value)
+	return nil
+}
+func (ConfChangeTransition) EnumDescriptor() ([]byte, []int) { return fileDescriptorRaft, []int{2} }
+
 type ConfChangeType int32
 
 const (
@@ -198,7 +254,7 @@
 	*x = ConfChangeType(value)
 	return nil
 }
-func (ConfChangeType) EnumDescriptor() ([]byte, []int) { return fileDescriptorRaft, []int{2} }
+func (ConfChangeType) EnumDescriptor() ([]byte, []int) { return fileDescriptorRaft, []int{3} }
 
 type Entry struct {
 	Term             uint64    `protobuf:"varint,2,opt,name=Term" json:"Term"`
@@ -270,9 +326,21 @@
 func (*HardState) Descriptor() ([]byte, []int) { return fileDescriptorRaft, []int{4} }
 
 type ConfState struct {
-	Nodes            []uint64 `protobuf:"varint,1,rep,name=nodes" json:"nodes,omitempty"`
-	Learners         []uint64 `protobuf:"varint,2,rep,name=learners" json:"learners,omitempty"`
-	XXX_unrecognized []byte   `json:"-"`
+	// The voters in the incoming config. (If the configuration is not joint,
+	// then the outgoing config is empty).
+	Voters []uint64 `protobuf:"varint,1,rep,name=voters" json:"voters,omitempty"`
+	// The learners in the incoming config.
+	Learners []uint64 `protobuf:"varint,2,rep,name=learners" json:"learners,omitempty"`
+	// The voters in the outgoing config.
+	VotersOutgoing []uint64 `protobuf:"varint,3,rep,name=voters_outgoing,json=votersOutgoing" json:"voters_outgoing,omitempty"`
+	// The nodes that will become learners when the outgoing config is removed.
+	// These nodes are necessarily currently in nodes_joint (or they would have
+	// been added to the incoming config right away).
+	LearnersNext []uint64 `protobuf:"varint,4,rep,name=learners_next,json=learnersNext" json:"learners_next,omitempty"`
+	// If set, the config is joint and Raft will automatically transition into
+	// the final config (i.e. remove the outgoing config) when this is safe.
+	AutoLeave        bool   `protobuf:"varint,5,opt,name=auto_leave,json=autoLeave" json:"auto_leave"`
+	XXX_unrecognized []byte `json:"-"`
 }
 
 func (m *ConfState) Reset()                    { *m = ConfState{} }
@@ -281,11 +349,14 @@
 func (*ConfState) Descriptor() ([]byte, []int) { return fileDescriptorRaft, []int{5} }
 
 type ConfChange struct {
-	ID               uint64         `protobuf:"varint,1,opt,name=ID" json:"ID"`
-	Type             ConfChangeType `protobuf:"varint,2,opt,name=Type,enum=raftpb.ConfChangeType" json:"Type"`
-	NodeID           uint64         `protobuf:"varint,3,opt,name=NodeID" json:"NodeID"`
-	Context          []byte         `protobuf:"bytes,4,opt,name=Context" json:"Context,omitempty"`
-	XXX_unrecognized []byte         `json:"-"`
+	Type    ConfChangeType `protobuf:"varint,2,opt,name=type,enum=raftpb.ConfChangeType" json:"type"`
+	NodeID  uint64         `protobuf:"varint,3,opt,name=node_id,json=nodeId" json:"node_id"`
+	Context []byte         `protobuf:"bytes,4,opt,name=context" json:"context,omitempty"`
+	// NB: this is used only by etcd to thread through a unique identifier.
+	// Ideally it should really use the Context instead. No counterpart to
+	// this field exists in ConfChangeV2.
+	ID               uint64 `protobuf:"varint,1,opt,name=id" json:"id"`
+	XXX_unrecognized []byte `json:"-"`
 }
 
 func (m *ConfChange) Reset()                    { *m = ConfChange{} }
@@ -293,6 +364,63 @@
 func (*ConfChange) ProtoMessage()               {}
 func (*ConfChange) Descriptor() ([]byte, []int) { return fileDescriptorRaft, []int{6} }
 
+// ConfChangeSingle is an individual configuration change operation. Multiple
+// such operations can be carried out atomically via a ConfChangeV2.
+type ConfChangeSingle struct {
+	Type             ConfChangeType `protobuf:"varint,1,opt,name=type,enum=raftpb.ConfChangeType" json:"type"`
+	NodeID           uint64         `protobuf:"varint,2,opt,name=node_id,json=nodeId" json:"node_id"`
+	XXX_unrecognized []byte         `json:"-"`
+}
+
+func (m *ConfChangeSingle) Reset()                    { *m = ConfChangeSingle{} }
+func (m *ConfChangeSingle) String() string            { return proto.CompactTextString(m) }
+func (*ConfChangeSingle) ProtoMessage()               {}
+func (*ConfChangeSingle) Descriptor() ([]byte, []int) { return fileDescriptorRaft, []int{7} }
+
+// ConfChangeV2 messages initiate configuration changes. They support both the
+// simple "one at a time" membership change protocol and full Joint Consensus
+// allowing for arbitrary changes in membership.
+//
+// The supplied context is treated as an opaque payload and can be used to
+// attach an action on the state machine to the application of the config change
+// proposal. Note that contrary to Joint Consensus as outlined in the Raft
+// paper[1], configuration changes become active when they are *applied* to the
+// state machine (not when they are appended to the log).
+//
+// The simple protocol can be used whenever only a single change is made.
+//
+// Non-simple changes require the use of Joint Consensus, for which two
+// configuration changes are run. The first configuration change specifies the
+// desired changes and transitions the Raft group into the joint configuration,
+// in which quorum requires a majority of both the pre-changes and post-changes
+// configuration. Joint Consensus avoids entering fragile intermediate
+// configurations that could compromise survivability. For example, without the
+// use of Joint Consensus and running across three availability zones with a
+// replication factor of three, it is not possible to replace a voter without
+// entering an intermediate configuration that does not survive the outage of
+// one availability zone.
+//
+// The provided ConfChangeTransition specifies how (and whether) Joint Consensus
+// is used, and assigns the task of leaving the joint configuration either to
+// Raft or the application. Leaving the joint configuration is accomplished by
+// proposing a ConfChangeV2 with only and optionally the Context field
+// populated.
+//
+// For details on Raft membership changes, see:
+//
+// [1]: https://github.com/ongardie/dissertation/blob/master/online-trim.pdf
+type ConfChangeV2 struct {
+	Transition       ConfChangeTransition `protobuf:"varint,1,opt,name=transition,enum=raftpb.ConfChangeTransition" json:"transition"`
+	Changes          []ConfChangeSingle   `protobuf:"bytes,2,rep,name=changes" json:"changes"`
+	Context          []byte               `protobuf:"bytes,3,opt,name=context" json:"context,omitempty"`
+	XXX_unrecognized []byte               `json:"-"`
+}
+
+func (m *ConfChangeV2) Reset()                    { *m = ConfChangeV2{} }
+func (m *ConfChangeV2) String() string            { return proto.CompactTextString(m) }
+func (*ConfChangeV2) ProtoMessage()               {}
+func (*ConfChangeV2) Descriptor() ([]byte, []int) { return fileDescriptorRaft, []int{8} }
+
 func init() {
 	proto.RegisterType((*Entry)(nil), "raftpb.Entry")
 	proto.RegisterType((*SnapshotMetadata)(nil), "raftpb.SnapshotMetadata")
@@ -301,8 +429,11 @@
 	proto.RegisterType((*HardState)(nil), "raftpb.HardState")
 	proto.RegisterType((*ConfState)(nil), "raftpb.ConfState")
 	proto.RegisterType((*ConfChange)(nil), "raftpb.ConfChange")
+	proto.RegisterType((*ConfChangeSingle)(nil), "raftpb.ConfChangeSingle")
+	proto.RegisterType((*ConfChangeV2)(nil), "raftpb.ConfChangeV2")
 	proto.RegisterEnum("raftpb.EntryType", EntryType_name, EntryType_value)
 	proto.RegisterEnum("raftpb.MessageType", MessageType_name, MessageType_value)
+	proto.RegisterEnum("raftpb.ConfChangeTransition", ConfChangeTransition_name, ConfChangeTransition_value)
 	proto.RegisterEnum("raftpb.ConfChangeType", ConfChangeType_name, ConfChangeType_value)
 }
 func (m *Entry) Marshal() (dAtA []byte, err error) {
@@ -535,8 +666,8 @@
 	_ = i
 	var l int
 	_ = l
-	if len(m.Nodes) > 0 {
-		for _, num := range m.Nodes {
+	if len(m.Voters) > 0 {
+		for _, num := range m.Voters {
 			dAtA[i] = 0x8
 			i++
 			i = encodeVarintRaft(dAtA, i, uint64(num))
@@ -549,6 +680,28 @@
 			i = encodeVarintRaft(dAtA, i, uint64(num))
 		}
 	}
+	if len(m.VotersOutgoing) > 0 {
+		for _, num := range m.VotersOutgoing {
+			dAtA[i] = 0x18
+			i++
+			i = encodeVarintRaft(dAtA, i, uint64(num))
+		}
+	}
+	if len(m.LearnersNext) > 0 {
+		for _, num := range m.LearnersNext {
+			dAtA[i] = 0x20
+			i++
+			i = encodeVarintRaft(dAtA, i, uint64(num))
+		}
+	}
+	dAtA[i] = 0x28
+	i++
+	if m.AutoLeave {
+		dAtA[i] = 1
+	} else {
+		dAtA[i] = 0
+	}
+	i++
 	if m.XXX_unrecognized != nil {
 		i += copy(dAtA[i:], m.XXX_unrecognized)
 	}
@@ -591,6 +744,75 @@
 	return i, nil
 }
 
+func (m *ConfChangeSingle) 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 *ConfChangeSingle) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	dAtA[i] = 0x8
+	i++
+	i = encodeVarintRaft(dAtA, i, uint64(m.Type))
+	dAtA[i] = 0x10
+	i++
+	i = encodeVarintRaft(dAtA, i, uint64(m.NodeID))
+	if m.XXX_unrecognized != nil {
+		i += copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	return i, nil
+}
+
+func (m *ConfChangeV2) 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 *ConfChangeV2) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	dAtA[i] = 0x8
+	i++
+	i = encodeVarintRaft(dAtA, i, uint64(m.Transition))
+	if len(m.Changes) > 0 {
+		for _, msg := range m.Changes {
+			dAtA[i] = 0x12
+			i++
+			i = encodeVarintRaft(dAtA, i, uint64(msg.Size()))
+			n, err := msg.MarshalTo(dAtA[i:])
+			if err != nil {
+				return 0, err
+			}
+			i += n
+		}
+	}
+	if m.Context != nil {
+		dAtA[i] = 0x1a
+		i++
+		i = encodeVarintRaft(dAtA, i, uint64(len(m.Context)))
+		i += copy(dAtA[i:], m.Context)
+	}
+	if m.XXX_unrecognized != nil {
+		i += copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	return i, nil
+}
+
 func encodeVarintRaft(dAtA []byte, offset int, v uint64) int {
 	for v >= 1<<7 {
 		dAtA[offset] = uint8(v&0x7f | 0x80)
@@ -689,8 +911,8 @@
 func (m *ConfState) Size() (n int) {
 	var l int
 	_ = l
-	if len(m.Nodes) > 0 {
-		for _, e := range m.Nodes {
+	if len(m.Voters) > 0 {
+		for _, e := range m.Voters {
 			n += 1 + sovRaft(uint64(e))
 		}
 	}
@@ -699,6 +921,17 @@
 			n += 1 + sovRaft(uint64(e))
 		}
 	}
+	if len(m.VotersOutgoing) > 0 {
+		for _, e := range m.VotersOutgoing {
+			n += 1 + sovRaft(uint64(e))
+		}
+	}
+	if len(m.LearnersNext) > 0 {
+		for _, e := range m.LearnersNext {
+			n += 1 + sovRaft(uint64(e))
+		}
+	}
+	n += 2
 	if m.XXX_unrecognized != nil {
 		n += len(m.XXX_unrecognized)
 	}
@@ -721,6 +954,37 @@
 	return n
 }
 
+func (m *ConfChangeSingle) Size() (n int) {
+	var l int
+	_ = l
+	n += 1 + sovRaft(uint64(m.Type))
+	n += 1 + sovRaft(uint64(m.NodeID))
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
+func (m *ConfChangeV2) Size() (n int) {
+	var l int
+	_ = l
+	n += 1 + sovRaft(uint64(m.Transition))
+	if len(m.Changes) > 0 {
+		for _, e := range m.Changes {
+			l = e.Size()
+			n += 1 + l + sovRaft(uint64(l))
+		}
+	}
+	if m.Context != nil {
+		l = len(m.Context)
+		n += 1 + l + sovRaft(uint64(l))
+	}
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
 func sovRaft(x uint64) (n int) {
 	for {
 		n++
@@ -1573,7 +1837,7 @@
 						break
 					}
 				}
-				m.Nodes = append(m.Nodes, v)
+				m.Voters = append(m.Voters, v)
 			} else if wireType == 2 {
 				var packedLen int
 				for shift := uint(0); ; shift += 7 {
@@ -1613,10 +1877,10 @@
 							break
 						}
 					}
-					m.Nodes = append(m.Nodes, v)
+					m.Voters = append(m.Voters, v)
 				}
 			} else {
-				return fmt.Errorf("proto: wrong wireType = %d for field Nodes", wireType)
+				return fmt.Errorf("proto: wrong wireType = %d for field Voters", wireType)
 			}
 		case 2:
 			if wireType == 0 {
@@ -1680,6 +1944,150 @@
 			} else {
 				return fmt.Errorf("proto: wrong wireType = %d for field Learners", wireType)
 			}
+		case 3:
+			if wireType == 0 {
+				var v uint64
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return ErrIntOverflowRaft
+					}
+					if iNdEx >= l {
+						return io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					v |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				m.VotersOutgoing = append(m.VotersOutgoing, v)
+			} else if wireType == 2 {
+				var packedLen int
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return ErrIntOverflowRaft
+					}
+					if iNdEx >= l {
+						return io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					packedLen |= (int(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				if packedLen < 0 {
+					return ErrInvalidLengthRaft
+				}
+				postIndex := iNdEx + packedLen
+				if postIndex > l {
+					return io.ErrUnexpectedEOF
+				}
+				for iNdEx < postIndex {
+					var v uint64
+					for shift := uint(0); ; shift += 7 {
+						if shift >= 64 {
+							return ErrIntOverflowRaft
+						}
+						if iNdEx >= l {
+							return io.ErrUnexpectedEOF
+						}
+						b := dAtA[iNdEx]
+						iNdEx++
+						v |= (uint64(b) & 0x7F) << shift
+						if b < 0x80 {
+							break
+						}
+					}
+					m.VotersOutgoing = append(m.VotersOutgoing, v)
+				}
+			} else {
+				return fmt.Errorf("proto: wrong wireType = %d for field VotersOutgoing", wireType)
+			}
+		case 4:
+			if wireType == 0 {
+				var v uint64
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return ErrIntOverflowRaft
+					}
+					if iNdEx >= l {
+						return io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					v |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				m.LearnersNext = append(m.LearnersNext, v)
+			} else if wireType == 2 {
+				var packedLen int
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return ErrIntOverflowRaft
+					}
+					if iNdEx >= l {
+						return io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					packedLen |= (int(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				if packedLen < 0 {
+					return ErrInvalidLengthRaft
+				}
+				postIndex := iNdEx + packedLen
+				if postIndex > l {
+					return io.ErrUnexpectedEOF
+				}
+				for iNdEx < postIndex {
+					var v uint64
+					for shift := uint(0); ; shift += 7 {
+						if shift >= 64 {
+							return ErrIntOverflowRaft
+						}
+						if iNdEx >= l {
+							return io.ErrUnexpectedEOF
+						}
+						b := dAtA[iNdEx]
+						iNdEx++
+						v |= (uint64(b) & 0x7F) << shift
+						if b < 0x80 {
+							break
+						}
+					}
+					m.LearnersNext = append(m.LearnersNext, v)
+				}
+			} else {
+				return fmt.Errorf("proto: wrong wireType = %d for field LearnersNext", wireType)
+			}
+		case 5:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field AutoLeave", wireType)
+			}
+			var v int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRaft
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				v |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			m.AutoLeave = bool(v != 0)
 		default:
 			iNdEx = preIndex
 			skippy, err := skipRaft(dAtA[iNdEx:])
@@ -1841,6 +2249,227 @@
 	}
 	return nil
 }
+func (m *ConfChangeSingle) 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 ErrIntOverflowRaft
+			}
+			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: ConfChangeSingle: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: ConfChangeSingle: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Type", wireType)
+			}
+			m.Type = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRaft
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Type |= (ConfChangeType(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 2:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field NodeID", wireType)
+			}
+			m.NodeID = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRaft
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.NodeID |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		default:
+			iNdEx = preIndex
+			skippy, err := skipRaft(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthRaft
+			}
+			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 (m *ConfChangeV2) 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 ErrIntOverflowRaft
+			}
+			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: ConfChangeV2: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: ConfChangeV2: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Transition", wireType)
+			}
+			m.Transition = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRaft
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Transition |= (ConfChangeTransition(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Changes", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRaft
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthRaft
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Changes = append(m.Changes, ConfChangeSingle{})
+			if err := m.Changes[len(m.Changes)-1].Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		case 3:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Context", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowRaft
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthRaft
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Context = append(m.Context[:0], dAtA[iNdEx:postIndex]...)
+			if m.Context == nil {
+				m.Context = []byte{}
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipRaft(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthRaft
+			}
+			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 skipRaft(dAtA []byte) (n int, err error) {
 	l := len(dAtA)
 	iNdEx := 0
@@ -1949,56 +2578,69 @@
 func init() { proto.RegisterFile("raft.proto", fileDescriptorRaft) }
 
 var fileDescriptorRaft = []byte{
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+	0x34, 0xd8, 0xe3, 0x4c, 0x11, 0xc7, 0x6e, 0x5e, 0x4b, 0x91, 0x10, 0xd7, 0xaa, 0x76, 0x93, 0x84,
+	0x94, 0xb1, 0x05, 0x90, 0xad, 0x87, 0x3c, 0x4d, 0x88, 0x67, 0x85, 0xe7, 0x42, 0x71, 0xb2, 0xa2,
+	0xbd, 0xd9, 0x8d, 0x61, 0x2b, 0x96, 0xd5, 0x4f, 0x00, 0xa9, 0x22, 0x81, 0xa6, 0x4e, 0xc6, 0x99,
+	0x54, 0x97, 0x3a, 0x4b, 0x0d, 0x37, 0x80, 0x14, 0x11, 0x73, 0xa8, 0x8e, 0x08, 0xad, 0x41, 0x1a,
+	0xbc, 0x89, 0x25, 0x67, 0xa3, 0x2b, 0x76, 0x39, 0xe1, 0x04, 0x70, 0x1d, 0x56, 0x6d, 0x20, 0xfd,
+	0xc5, 0x4d, 0x53, 0xd2, 0xb0, 0xb2, 0xfd, 0x2b, 0x3e, 0xfa, 0xe9, 0xbb, 0xa9, 0x90, 0xd3, 0x88,
+	0x34, 0x75, 0xd9, 0x83, 0x34, 0x30, 0x17, 0x34, 0xe6, 0xf2, 0x98, 0x33, 0x9f, 0x4b, 0xb2, 0x6a,
+	0x4f, 0x9f, 0x85, 0x11, 0x17, 0x53, 0x75, 0x22, 0x7e, 0x26, 0x2d, 0x6b, 0x66, 0xc8, 0x99, 0x6f,
+	0x7e, 0x61, 0x64, 0xcd, 0x9a, 0x99, 0x21, 0xc6, 0x0c, 0xb1, 0xf5, 0xbe, 0x96, 0xdc, 0x94, 0xb8,
+	0x6e, 0xb3, 0xda, 0xbd, 0xd1, 0xe0, 0xf6, 0x6f, 0x0e, 0x6c, 0x3c, 0x36, 0x1e, 0xb8, 0x05, 0xf4,
+	0x31, 0x7c, 0x77, 0xaa, 0x04, 0x29, 0xe1, 0xa7, 0xf0, 0xff, 0xc7, 0xd8, 0x6f, 0x44, 0x18, 0xab,
+	0xa3, 0x28, 0x99, 0x84, 0xa3, 0x50, 0x5f, 0xc5, 0xc7, 0x64, 0xaf, 0x6e, 0xac, 0xcc, 0xdd, 0xbe,
+	0x85, 0xd6, 0xe2, 0x47, 0xa1, 0x9b, 0x31, 0x47, 0x76, 0x7d, 0x5f, 0x8f, 0x3f, 0x29, 0x21, 0x2d,
+	0x9a, 0x1d, 0xf2, 0x48, 0x5c, 0x73, 0xc3, 0x38, 0x8b, 0xcc, 0x9b, 0xc4, 0x67, 0x2a, 0x63, 0xdc,
+	0xc5, 0x42, 0x76, 0x7d, 0xff, 0x38, 0x7b, 0x7b, 0x0c, 0x5b, 0xde, 0xa3, 0x77, 0x1f, 0xda, 0xa5,
+	0x77, 0x1f, 0xda, 0xa5, 0xbb, 0xfb, 0xb6, 0xf3, 0xee, 0xbe, 0xed, 0xfc, 0x7d, 0xdf, 0x76, 0x7e,
+	0xff, 0xa7, 0x5d, 0xfa, 0x37, 0x00, 0x00, 0xff, 0xff, 0x87, 0x11, 0x6d, 0xd6, 0xaf, 0x08, 0x00,
+	0x00,
 }
diff --git a/vendor/go.etcd.io/etcd/raft/raftpb/raft.proto b/vendor/go.etcd.io/etcd/raft/raftpb/raft.proto
index 644ce7b..23d62ec 100644
--- a/vendor/go.etcd.io/etcd/raft/raftpb/raft.proto
+++ b/vendor/go.etcd.io/etcd/raft/raftpb/raft.proto
@@ -10,8 +10,9 @@
 option (gogoproto.goproto_enum_prefix_all) = false;
 
 enum EntryType {
-	EntryNormal     = 0;
-	EntryConfChange = 1;
+	EntryNormal       = 0;
+	EntryConfChange   = 1; // corresponds to pb.ConfChange
+	EntryConfChangeV2 = 2; // corresponds to pb.ConfChangeV2
 }
 
 message Entry {
@@ -75,9 +76,41 @@
 	optional uint64 commit = 3 [(gogoproto.nullable) = false];
 }
 
+// ConfChangeTransition specifies the behavior of a configuration change with
+// respect to joint consensus.
+enum ConfChangeTransition {
+	// Automatically use the simple protocol if possible, otherwise fall back
+	// to ConfChangeJointImplicit. Most applications will want to use this.
+	ConfChangeTransitionAuto          = 0;
+	// Use joint consensus unconditionally, and transition out of them
+	// automatically (by proposing a zero configuration change).
+	//
+	// This option is suitable for applications that want to minimize the time
+	// spent in the joint configuration and do not store the joint configuration
+	// in the state machine (outside of InitialState).
+	ConfChangeTransitionJointImplicit = 1;
+	// Use joint consensus and remain in the joint configuration until the
+	// application proposes a no-op configuration change. This is suitable for
+	// applications that want to explicitly control the transitions, for example
+	// to use a custom payload (via the Context field).
+	ConfChangeTransitionJointExplicit = 2;
+}
+
 message ConfState {
-	repeated uint64 nodes    = 1;
-	repeated uint64 learners = 2;
+	// The voters in the incoming config. (If the configuration is not joint,
+	// then the outgoing config is empty).
+	repeated uint64 voters = 1;
+	// The learners in the incoming config.
+	repeated uint64 learners          = 2;
+	// The voters in the outgoing config.
+	repeated uint64 voters_outgoing   = 3;
+	// The nodes that will become learners when the outgoing config is removed.
+	// These nodes are necessarily currently in nodes_joint (or they would have
+	// been added to the incoming config right away).
+	repeated uint64 learners_next     = 4;
+	// If set, the config is joint and Raft will automatically transition into
+	// the final config (i.e. remove the outgoing config) when this is safe.
+	optional bool   auto_leave        = 5 [(gogoproto.nullable) = false];
 }
 
 enum ConfChangeType {
@@ -88,8 +121,57 @@
 }
 
 message ConfChange {
-	optional uint64          ID      = 1 [(gogoproto.nullable) = false];
-	optional ConfChangeType  Type    = 2 [(gogoproto.nullable) = false];
-	optional uint64          NodeID  = 3 [(gogoproto.nullable) = false];
-	optional bytes           Context = 4;
+	optional ConfChangeType  type    = 2 [(gogoproto.nullable) = false];
+	optional uint64          node_id = 3 [(gogoproto.nullable) = false, (gogoproto.customname) = "NodeID" ];
+	optional bytes           context = 4;
+
+	// NB: this is used only by etcd to thread through a unique identifier.
+	// Ideally it should really use the Context instead. No counterpart to
+	// this field exists in ConfChangeV2.
+	optional uint64          id      = 1 [(gogoproto.nullable) = false, (gogoproto.customname) = "ID" ];
+}
+
+// ConfChangeSingle is an individual configuration change operation. Multiple
+// such operations can be carried out atomically via a ConfChangeV2.
+message ConfChangeSingle {
+	optional ConfChangeType  type    = 1 [(gogoproto.nullable) = false];
+	optional uint64          node_id = 2 [(gogoproto.nullable) = false, (gogoproto.customname) = "NodeID"];
+}
+
+// ConfChangeV2 messages initiate configuration changes. They support both the
+// simple "one at a time" membership change protocol and full Joint Consensus
+// allowing for arbitrary changes in membership.
+//
+// The supplied context is treated as an opaque payload and can be used to
+// attach an action on the state machine to the application of the config change
+// proposal. Note that contrary to Joint Consensus as outlined in the Raft
+// paper[1], configuration changes become active when they are *applied* to the
+// state machine (not when they are appended to the log).
+//
+// The simple protocol can be used whenever only a single change is made.
+//
+// Non-simple changes require the use of Joint Consensus, for which two
+// configuration changes are run. The first configuration change specifies the
+// desired changes and transitions the Raft group into the joint configuration,
+// in which quorum requires a majority of both the pre-changes and post-changes
+// configuration. Joint Consensus avoids entering fragile intermediate
+// configurations that could compromise survivability. For example, without the
+// use of Joint Consensus and running across three availability zones with a
+// replication factor of three, it is not possible to replace a voter without
+// entering an intermediate configuration that does not survive the outage of
+// one availability zone.
+//
+// The provided ConfChangeTransition specifies how (and whether) Joint Consensus
+// is used, and assigns the task of leaving the joint configuration either to
+// Raft or the application. Leaving the joint configuration is accomplished by
+// proposing a ConfChangeV2 with only and optionally the Context field
+// populated.
+//
+// For details on Raft membership changes, see:
+//
+// [1]: https://github.com/ongardie/dissertation/blob/master/online-trim.pdf
+message ConfChangeV2 {
+	optional ConfChangeTransition transition = 1 [(gogoproto.nullable) = false];
+	repeated ConfChangeSingle     changes =    2 [(gogoproto.nullable) = false];
+	optional bytes                context =    3;
 }
diff --git a/vendor/go.etcd.io/etcd/raft/rawnode.go b/vendor/go.etcd.io/etcd/raft/rawnode.go
index 77183b7..90eb694 100644
--- a/vendor/go.etcd.io/etcd/raft/rawnode.go
+++ b/vendor/go.etcd.io/etcd/raft/rawnode.go
@@ -37,82 +37,20 @@
 	prevHardSt pb.HardState
 }
 
-func (rn *RawNode) newReady() Ready {
-	return newReady(rn.raft, rn.prevSoftSt, rn.prevHardSt)
-}
-
-func (rn *RawNode) commitReady(rd Ready) {
-	if rd.SoftState != nil {
-		rn.prevSoftSt = rd.SoftState
-	}
-	if !IsEmptyHardState(rd.HardState) {
-		rn.prevHardSt = rd.HardState
-	}
-
-	// If entries were applied (or a snapshot), update our cursor for
-	// the next Ready. Note that if the current HardState contains a
-	// new Commit index, this does not mean that we're also applying
-	// all of the new entries due to commit pagination by size.
-	if index := rd.appliedCursor(); index > 0 {
-		rn.raft.raftLog.appliedTo(index)
-	}
-
-	if len(rd.Entries) > 0 {
-		e := rd.Entries[len(rd.Entries)-1]
-		rn.raft.raftLog.stableTo(e.Index, e.Term)
-	}
-	if !IsEmptySnap(rd.Snapshot) {
-		rn.raft.raftLog.stableSnapTo(rd.Snapshot.Metadata.Index)
-	}
-	if len(rd.ReadStates) != 0 {
-		rn.raft.readStates = nil
-	}
-}
-
-// NewRawNode returns a new RawNode given configuration and a list of raft peers.
-func NewRawNode(config *Config, peers []Peer) (*RawNode, error) {
-	if config.ID == 0 {
-		panic("config.ID must not be zero")
-	}
+// NewRawNode instantiates a RawNode from the given configuration.
+//
+// See Bootstrap() for bootstrapping an initial state; this replaces the former
+// 'peers' argument to this method (with identical behavior). However, It is
+// recommended that instead of calling Bootstrap, applications bootstrap their
+// state manually by setting up a Storage that has a first index > 1 and which
+// stores the desired ConfState as its InitialState.
+func NewRawNode(config *Config) (*RawNode, error) {
 	r := newRaft(config)
 	rn := &RawNode{
 		raft: r,
 	}
-	lastIndex, err := config.Storage.LastIndex()
-	if err != nil {
-		panic(err) // TODO(bdarnell)
-	}
-	// If the log is empty, this is a new RawNode (like StartNode); otherwise it's
-	// restoring an existing RawNode (like RestartNode).
-	// TODO(bdarnell): rethink RawNode initialization and whether the application needs
-	// to be able to tell us when it expects the RawNode to exist.
-	if lastIndex == 0 {
-		r.becomeFollower(1, None)
-		ents := make([]pb.Entry, len(peers))
-		for i, peer := range peers {
-			cc := pb.ConfChange{Type: pb.ConfChangeAddNode, NodeID: peer.ID, Context: peer.Context}
-			data, err := cc.Marshal()
-			if err != nil {
-				panic("unexpected marshal error")
-			}
-
-			ents[i] = pb.Entry{Type: pb.EntryConfChange, Term: 1, Index: uint64(i + 1), Data: data}
-		}
-		r.raftLog.append(ents...)
-		r.raftLog.committed = uint64(len(ents))
-		for _, peer := range peers {
-			r.applyConfChange(pb.ConfChange{NodeID: peer.ID, Type: pb.ConfChangeAddNode})
-		}
-	}
-
-	// Set the initial hard and soft states after performing all initialization.
 	rn.prevSoftSt = r.softState()
-	if lastIndex == 0 {
-		rn.prevHardSt = emptyState
-	} else {
-		rn.prevHardSt = r.hardState()
-	}
-
+	rn.prevHardSt = r.hardState()
 	return rn, nil
 }
 
@@ -150,23 +88,19 @@
 		}})
 }
 
-// ProposeConfChange proposes a config change.
-func (rn *RawNode) ProposeConfChange(cc pb.ConfChange) error {
-	data, err := cc.Marshal()
+// ProposeConfChange proposes a config change. See (Node).ProposeConfChange for
+// details.
+func (rn *RawNode) ProposeConfChange(cc pb.ConfChangeI) error {
+	m, err := confChangeToMsg(cc)
 	if err != nil {
 		return err
 	}
-	return rn.raft.Step(pb.Message{
-		Type: pb.MsgProp,
-		Entries: []pb.Entry{
-			{Type: pb.EntryConfChange, Data: data},
-		},
-	})
+	return rn.raft.Step(m)
 }
 
 // ApplyConfChange applies a config change to the local node.
-func (rn *RawNode) ApplyConfChange(cc pb.ConfChange) *pb.ConfState {
-	cs := rn.raft.applyConfChange(cc)
+func (rn *RawNode) ApplyConfChange(cc pb.ConfChangeI) *pb.ConfState {
+	cs := rn.raft.applyConfChange(cc.AsV2())
 	return &cs
 }
 
@@ -182,14 +116,35 @@
 	return ErrStepPeerNotFound
 }
 
-// Ready returns the current point-in-time state of this RawNode.
+// Ready returns the outstanding work that the application needs to handle. This
+// includes appending and applying entries or a snapshot, updating the HardState,
+// and sending messages. The returned Ready() *must* be handled and subsequently
+// passed back via Advance().
 func (rn *RawNode) Ready() Ready {
-	rd := rn.newReady()
-	rn.raft.msgs = nil
-	rn.raft.reduceUncommittedSize(rd.CommittedEntries)
+	rd := rn.readyWithoutAccept()
+	rn.acceptReady(rd)
 	return rd
 }
 
+// readyWithoutAccept returns a Ready. This is a read-only operation, i.e. there
+// is no obligation that the Ready must be handled.
+func (rn *RawNode) readyWithoutAccept() Ready {
+	return newReady(rn.raft, rn.prevSoftSt, rn.prevHardSt)
+}
+
+// acceptReady is called when the consumer of the RawNode has decided to go
+// ahead and handle a Ready. Nothing must alter the state of the RawNode between
+// this call and the prior call to Ready().
+func (rn *RawNode) acceptReady(rd Ready) {
+	if rd.SoftState != nil {
+		rn.prevSoftSt = rd.SoftState
+	}
+	if len(rd.ReadStates) != 0 {
+		rn.raft.readStates = nil
+	}
+	rn.raft.msgs = nil
+}
+
 // HasReady called when RawNode user need to check if any Ready pending.
 // Checking logic in this method should be consistent with Ready.containsUpdates().
 func (rn *RawNode) HasReady() bool {
@@ -215,21 +170,23 @@
 // Advance notifies the RawNode that the application has applied and saved progress in the
 // last Ready results.
 func (rn *RawNode) Advance(rd Ready) {
-	rn.commitReady(rd)
+	if !IsEmptyHardState(rd.HardState) {
+		rn.prevHardSt = rd.HardState
+	}
+	rn.raft.advance(rd)
 }
 
-// Status returns the current status of the given group.
-func (rn *RawNode) Status() *Status {
+// Status returns the current status of the given group. This allocates, see
+// BasicStatus and WithProgress for allocation-friendlier choices.
+func (rn *RawNode) Status() Status {
 	status := getStatus(rn.raft)
-	return &status
+	return status
 }
 
-// StatusWithoutProgress returns a Status without populating the Progress field
-// (and returns the Status as a value to avoid forcing it onto the heap). This
-// is more performant if the Progress is not required. See WithProgress for an
-// allocation-free way to introspect the Progress.
-func (rn *RawNode) StatusWithoutProgress() Status {
-	return getStatusWithoutProgress(rn.raft)
+// BasicStatus returns a BasicStatus. Notably this does not contain the
+// Progress map; see WithProgress for an allocation-free way to inspect it.
+func (rn *RawNode) BasicStatus() BasicStatus {
+	return getBasicStatus(rn.raft)
 }
 
 // ProgressType indicates the type of replica a Progress corresponds to.
diff --git a/vendor/go.etcd.io/etcd/raft/status.go b/vendor/go.etcd.io/etcd/raft/status.go
index bf4898c..adc6048 100644
--- a/vendor/go.etcd.io/etcd/raft/status.go
+++ b/vendor/go.etcd.io/etcd/raft/status.go
@@ -21,14 +21,22 @@
 	"go.etcd.io/etcd/raft/tracker"
 )
 
+// Status contains information about this Raft peer and its view of the system.
+// The Progress is only populated on the leader.
 type Status struct {
+	BasicStatus
+	Config   tracker.Config
+	Progress map[uint64]tracker.Progress
+}
+
+// BasicStatus contains basic information about the Raft peer. It does not allocate.
+type BasicStatus struct {
 	ID uint64
 
 	pb.HardState
 	SoftState
 
-	Applied  uint64
-	Progress map[uint64]tracker.Progress
+	Applied uint64
 
 	LeadTransferee uint64
 }
@@ -37,19 +45,17 @@
 	m := make(map[uint64]tracker.Progress)
 	r.prs.Visit(func(id uint64, pr *tracker.Progress) {
 		var p tracker.Progress
-		p, pr = *pr, nil /* avoid accidental reuse below */
-
-		// The inflight buffer is tricky to copy and besides, it isn't exposed
-		// to the client, so pretend it's nil.
-		p.Inflights = nil
+		p = *pr
+		p.Inflights = pr.Inflights.Clone()
+		pr = nil
 
 		m[id] = p
 	})
 	return m
 }
 
-func getStatusWithoutProgress(r *raft) Status {
-	s := Status{
+func getBasicStatus(r *raft) BasicStatus {
+	s := BasicStatus{
 		ID:             r.id,
 		LeadTransferee: r.leadTransferee,
 	}
@@ -61,10 +67,12 @@
 
 // getStatus gets a copy of the current raft status.
 func getStatus(r *raft) Status {
-	s := getStatusWithoutProgress(r)
+	var s Status
+	s.BasicStatus = getBasicStatus(r)
 	if s.RaftState == StateLeader {
 		s.Progress = getProgressCopy(r)
 	}
+	s.Config = r.prs.Config.Clone()
 	return s
 }
 
diff --git a/vendor/go.etcd.io/etcd/raft/storage.go b/vendor/go.etcd.io/etcd/raft/storage.go
index 14ad686..6be5745 100644
--- a/vendor/go.etcd.io/etcd/raft/storage.go
+++ b/vendor/go.etcd.io/etcd/raft/storage.go
@@ -44,6 +44,8 @@
 // become inoperable and refuse to participate in elections; the
 // application is responsible for cleanup and recovery in this case.
 type Storage interface {
+	// TODO(tbg): split this into two interfaces, LogStorage and StateStorage.
+
 	// InitialState returns the saved HardState and ConfState information.
 	InitialState() (pb.HardState, pb.ConfState, error)
 	// Entries returns a slice of log entries in the range [lo,hi).
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/inflights.go b/vendor/go.etcd.io/etcd/raft/tracker/inflights.go
index 9e209e2..1a05634 100644
--- a/vendor/go.etcd.io/etcd/raft/tracker/inflights.go
+++ b/vendor/go.etcd.io/etcd/raft/tracker/inflights.go
@@ -40,6 +40,14 @@
 	}
 }
 
+// Clone returns an *Inflights that is identical to but shares no memory with
+// the receiver.
+func (in *Inflights) Clone() *Inflights {
+	ins := *in
+	ins.buffer = append([]uint64(nil), in.buffer...)
+	return &ins
+}
+
 // Add notifies the Inflights that a new message with the given index is being
 // dispatched. Full() must be called prior to Add() to verify that there is room
 // for one more message, and consecutive calls to add Add() must provide a
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/progress.go b/vendor/go.etcd.io/etcd/raft/tracker/progress.go
index 697277b..62c81f4 100644
--- a/vendor/go.etcd.io/etcd/raft/tracker/progress.go
+++ b/vendor/go.etcd.io/etcd/raft/tracker/progress.go
@@ -52,6 +52,8 @@
 	// RecentActive is true if the progress is recently active. Receiving any messages
 	// from the corresponding follower indicates the progress is active.
 	// RecentActive can be reset to false after an election timeout.
+	//
+	// TODO(tbg): the leader should always have this set to true.
 	RecentActive bool
 
 	// ProbeSent is used while this follower is in StateProbe. When ProbeSent is
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/tracker.go b/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
index a2638f5..a458114 100644
--- a/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
+++ b/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
@@ -20,11 +20,17 @@
 	"strings"
 
 	"go.etcd.io/etcd/raft/quorum"
+	pb "go.etcd.io/etcd/raft/raftpb"
 )
 
 // Config reflects the configuration tracked in a ProgressTracker.
 type Config struct {
 	Voters quorum.JointConfig
+	// AutoLeave is true if the configuration is joint and a transition to the
+	// incoming configuration should be carried out automatically by Raft when
+	// this is possible. If false, the configuration will be joint until the
+	// application initiates the transition manually.
+	AutoLeave bool
 	// Learners is a set of IDs corresponding to the learners active in the
 	// current configuration.
 	//
@@ -80,6 +86,9 @@
 	if c.LearnersNext != nil {
 		fmt.Fprintf(&buf, " learners_next=%s", quorum.MajorityConfig(c.LearnersNext).String())
 	}
+	if c.AutoLeave {
+		fmt.Fprintf(&buf, " autoleave")
+	}
 	return buf.String()
 }
 
@@ -133,6 +142,17 @@
 	return p
 }
 
+// ConfState returns a ConfState representing the active configuration.
+func (p *ProgressTracker) ConfState() pb.ConfState {
+	return pb.ConfState{
+		Voters:         p.Voters[0].Slice(),
+		VotersOutgoing: p.Voters[1].Slice(),
+		Learners:       quorum.MajorityConfig(p.Learners).Slice(),
+		LearnersNext:   quorum.MajorityConfig(p.LearnersNext).Slice(),
+		AutoLeave:      p.AutoLeave,
+	}
+}
+
 // IsSingleton returns true if (and only if) there is only one voting member
 // (i.e. the leader) in the current configuration.
 func (p *ProgressTracker) IsSingleton() bool {
@@ -158,10 +178,35 @@
 	return uint64(p.Voters.CommittedIndex(matchAckIndexer(p.Progress)))
 }
 
-// Visit invokes the supplied closure for all tracked progresses.
+func insertionSort(sl []uint64) {
+	a, b := 0, len(sl)
+	for i := a + 1; i < b; i++ {
+		for j := i; j > a && sl[j] < sl[j-1]; j-- {
+			sl[j], sl[j-1] = sl[j-1], sl[j]
+		}
+	}
+}
+
+// Visit invokes the supplied closure for all tracked progresses in stable order.
 func (p *ProgressTracker) Visit(f func(id uint64, pr *Progress)) {
-	for id, pr := range p.Progress {
-		f(id, pr)
+	n := len(p.Progress)
+	// We need to sort the IDs and don't want to allocate since this is hot code.
+	// The optimization here mirrors that in `(MajorityConfig).CommittedIndex`,
+	// see there for details.
+	var sl [7]uint64
+	ids := sl[:]
+	if len(sl) >= n {
+		ids = sl[:n]
+	} else {
+		ids = make([]uint64, n)
+	}
+	for id := range p.Progress {
+		n--
+		ids[n] = id
+	}
+	insertionSort(ids)
+	for _, id := range ids {
+		f(id, p.Progress[id])
 	}
 }
 
@@ -192,6 +237,9 @@
 
 // LearnerNodes returns a sorted slice of learners.
 func (p *ProgressTracker) LearnerNodes() []uint64 {
+	if len(p.Learners) == 0 {
+		return nil
+	}
 	nodes := make([]uint64, 0, len(p.Learners))
 	for id := range p.Learners {
 		nodes = append(nodes, id)
diff --git a/vendor/go.etcd.io/etcd/raft/util.go b/vendor/go.etcd.io/etcd/raft/util.go
index c145d26..785cf73 100644
--- a/vendor/go.etcd.io/etcd/raft/util.go
+++ b/vendor/go.etcd.io/etcd/raft/util.go
@@ -17,6 +17,7 @@
 import (
 	"bytes"
 	"fmt"
+	"strings"
 
 	pb "go.etcd.io/etcd/raft/raftpb"
 )
@@ -25,13 +26,6 @@
 	return []byte(fmt.Sprintf("%q", st.String())), nil
 }
 
-// uint64Slice implements sort interface
-type uint64Slice []uint64
-
-func (p uint64Slice) Len() int           { return len(p) }
-func (p uint64Slice) Less(i, j int) bool { return p[i] < p[j] }
-func (p uint64Slice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
-
 func min(a, b uint64) uint64 {
 	if a > b {
 		return b
@@ -67,6 +61,69 @@
 	}
 }
 
+func DescribeHardState(hs pb.HardState) string {
+	var buf strings.Builder
+	fmt.Fprintf(&buf, "Term:%d", hs.Term)
+	if hs.Vote != 0 {
+		fmt.Fprintf(&buf, " Vote:%d", hs.Vote)
+	}
+	fmt.Fprintf(&buf, " Commit:%d", hs.Commit)
+	return buf.String()
+}
+
+func DescribeSoftState(ss SoftState) string {
+	return fmt.Sprintf("Lead:%d State:%s", ss.Lead, ss.RaftState)
+}
+
+func DescribeConfState(state pb.ConfState) string {
+	return fmt.Sprintf(
+		"Voters:%v VotersOutgoing:%v Learners:%v LearnersNext:%v AutoLeave:%v",
+		state.Voters, state.VotersOutgoing, state.Learners, state.LearnersNext, state.AutoLeave,
+	)
+}
+
+func DescribeSnapshot(snap pb.Snapshot) string {
+	m := snap.Metadata
+	return fmt.Sprintf("Index:%d Term:%d ConfState:%s", m.Index, m.Term, DescribeConfState(m.ConfState))
+}
+
+func DescribeReady(rd Ready, f EntryFormatter) string {
+	var buf strings.Builder
+	if rd.SoftState != nil {
+		fmt.Fprint(&buf, DescribeSoftState(*rd.SoftState))
+		buf.WriteByte('\n')
+	}
+	if !IsEmptyHardState(rd.HardState) {
+		fmt.Fprintf(&buf, "HardState %s", DescribeHardState(rd.HardState))
+		buf.WriteByte('\n')
+	}
+	if len(rd.ReadStates) > 0 {
+		fmt.Fprintf(&buf, "ReadStates %v\n", rd.ReadStates)
+	}
+	if len(rd.Entries) > 0 {
+		buf.WriteString("Entries:\n")
+		fmt.Fprint(&buf, DescribeEntries(rd.Entries, f))
+	}
+	if !IsEmptySnap(rd.Snapshot) {
+		fmt.Fprintf(&buf, "Snapshot %s\n", DescribeSnapshot(rd.Snapshot))
+	}
+	if len(rd.CommittedEntries) > 0 {
+		buf.WriteString("CommittedEntries:\n")
+		fmt.Fprint(&buf, DescribeEntries(rd.CommittedEntries, f))
+	}
+	if len(rd.Messages) > 0 {
+		buf.WriteString("Messages:\n")
+		for _, msg := range rd.Messages {
+			fmt.Fprint(&buf, DescribeMessage(msg, f))
+			buf.WriteByte('\n')
+		}
+	}
+	if buf.Len() > 0 {
+		return fmt.Sprintf("Ready MustSync=%t:\n%s", rd.MustSync, buf.String())
+	}
+	return "<empty Ready>"
+}
+
 // EntryFormatter can be implemented by the application to provide human-readable formatting
 // of entry data. Nil is a valid EntryFormatter and will use a default format.
 type EntryFormatter func([]byte) string
@@ -93,7 +150,7 @@
 		fmt.Fprintf(&buf, "]")
 	}
 	if !IsEmptySnap(m.Snapshot) {
-		fmt.Fprintf(&buf, " Snapshot:%v", m.Snapshot)
+		fmt.Fprintf(&buf, " Snapshot: %s", DescribeSnapshot(m.Snapshot))
 	}
 	return buf.String()
 }
@@ -107,13 +164,39 @@
 // DescribeEntry returns a concise human-readable description of an
 // Entry for debugging.
 func DescribeEntry(e pb.Entry, f EntryFormatter) string {
-	var formatted string
-	if e.Type == pb.EntryNormal && f != nil {
-		formatted = f(e.Data)
-	} else {
-		formatted = fmt.Sprintf("%q", e.Data)
+	if f == nil {
+		f = func(data []byte) string { return fmt.Sprintf("%q", data) }
 	}
-	return fmt.Sprintf("%d/%d %s %s", e.Term, e.Index, e.Type, formatted)
+
+	formatConfChange := func(cc pb.ConfChangeI) string {
+		// TODO(tbg): give the EntryFormatter a type argument so that it gets
+		// a chance to expose the Context.
+		return pb.ConfChangesToString(cc.AsV2().Changes)
+	}
+
+	var formatted string
+	switch e.Type {
+	case pb.EntryNormal:
+		formatted = f(e.Data)
+	case pb.EntryConfChange:
+		var cc pb.ConfChange
+		if err := cc.Unmarshal(e.Data); err != nil {
+			formatted = err.Error()
+		} else {
+			formatted = formatConfChange(cc)
+		}
+	case pb.EntryConfChangeV2:
+		var cc pb.ConfChangeV2
+		if err := cc.Unmarshal(e.Data); err != nil {
+			formatted = err.Error()
+		} else {
+			formatted = formatConfChange(cc)
+		}
+	}
+	if formatted != "" {
+		formatted = " " + formatted
+	}
+	return fmt.Sprintf("%d/%d %s%s", e.Term, e.Index, e.Type, formatted)
 }
 
 // DescribeEntries calls DescribeEntry for each Entry, adding a newline to
@@ -140,3 +223,11 @@
 	}
 	return ents[:limit]
 }
+
+func assertConfStatesEquivalent(l Logger, cs1, cs2 pb.ConfState) {
+	err := cs1.Equivalent(cs2)
+	if err == nil {
+		return
+	}
+	l.Panic(err)
+}