[VOL-5486] Upgrade library versions

Change-Id: I8b4e88699e03f44ee13e467867f45ae3f0a63c4b
Signed-off-by: Abhay Kumar <abhay.kumar@radisys.com>
diff --git a/vendor/go.etcd.io/etcd/server/v3/etcdserver/bootstrap.go b/vendor/go.etcd.io/etcd/server/v3/etcdserver/bootstrap.go
new file mode 100644
index 0000000..b76d979
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/server/v3/etcdserver/bootstrap.go
@@ -0,0 +1,733 @@
+// Copyright 2021 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 etcdserver
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/coreos/go-semver/semver"
+	"github.com/dustin/go-humanize"
+	"go.uber.org/zap"
+
+	"go.etcd.io/etcd/api/v3/etcdserverpb"
+	"go.etcd.io/etcd/client/pkg/v3/fileutil"
+	"go.etcd.io/etcd/client/pkg/v3/types"
+	"go.etcd.io/etcd/pkg/v3/pbutil"
+	"go.etcd.io/etcd/server/v3/config"
+	"go.etcd.io/etcd/server/v3/etcdserver/api"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/membership"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/rafthttp"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/snap"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/v2discovery"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/v2store"
+	"go.etcd.io/etcd/server/v3/etcdserver/api/v3discovery"
+	"go.etcd.io/etcd/server/v3/etcdserver/cindex"
+	servererrors "go.etcd.io/etcd/server/v3/etcdserver/errors"
+	serverstorage "go.etcd.io/etcd/server/v3/storage"
+	"go.etcd.io/etcd/server/v3/storage/backend"
+	"go.etcd.io/etcd/server/v3/storage/schema"
+	"go.etcd.io/etcd/server/v3/storage/wal"
+	"go.etcd.io/etcd/server/v3/storage/wal/walpb"
+	"go.etcd.io/raft/v3"
+	"go.etcd.io/raft/v3/raftpb"
+)
+
+func bootstrap(cfg config.ServerConfig) (b *bootstrappedServer, err error) {
+	if cfg.MaxRequestBytes > recommendedMaxRequestBytes {
+		cfg.Logger.Warn(
+			"exceeded recommended request limit",
+			zap.Uint("max-request-bytes", cfg.MaxRequestBytes),
+			zap.String("max-request-size", humanize.Bytes(uint64(cfg.MaxRequestBytes))),
+			zap.Int("recommended-request-bytes", recommendedMaxRequestBytes),
+			zap.String("recommended-request-size", recommendedMaxRequestBytesString),
+		)
+	}
+
+	if terr := fileutil.TouchDirAll(cfg.Logger, cfg.DataDir); terr != nil {
+		return nil, fmt.Errorf("cannot access data directory: %w", terr)
+	}
+
+	if terr := fileutil.TouchDirAll(cfg.Logger, cfg.MemberDir()); terr != nil {
+		return nil, fmt.Errorf("cannot access member directory: %w", terr)
+	}
+	ss := bootstrapSnapshot(cfg)
+	prt, err := rafthttp.NewRoundTripper(cfg.PeerTLSInfo, cfg.PeerDialTimeout())
+	if err != nil {
+		return nil, err
+	}
+
+	haveWAL := wal.Exist(cfg.WALDir())
+	st := v2store.New(StoreClusterPrefix, StoreKeysPrefix)
+	backend, err := bootstrapBackend(cfg, haveWAL, st, ss)
+	if err != nil {
+		return nil, err
+	}
+	var bwal *bootstrappedWAL
+
+	if haveWAL {
+		if err = fileutil.IsDirWriteable(cfg.WALDir()); err != nil {
+			return nil, fmt.Errorf("cannot write to WAL directory: %w", err)
+		}
+		cfg.Logger.Info("Bootstrapping WAL from snapshot")
+		bwal = bootstrapWALFromSnapshot(cfg, backend.snapshot, backend.ci)
+	}
+
+	cfg.Logger.Info("bootstrapping cluster")
+	cluster, err := bootstrapCluster(cfg, bwal, prt)
+	if err != nil {
+		backend.Close()
+		return nil, err
+	}
+
+	cfg.Logger.Info("bootstrapping storage")
+	s := bootstrapStorage(cfg, st, backend, bwal, cluster)
+
+	if err = cluster.Finalize(cfg, s); err != nil {
+		backend.Close()
+		return nil, err
+	}
+
+	cfg.Logger.Info("bootstrapping raft")
+	raft := bootstrapRaft(cfg, cluster, s.wal)
+	return &bootstrappedServer{
+		prt:     prt,
+		ss:      ss,
+		storage: s,
+		cluster: cluster,
+		raft:    raft,
+	}, nil
+}
+
+type bootstrappedServer struct {
+	storage *bootstrappedStorage
+	cluster *bootstrappedCluster
+	raft    *bootstrappedRaft
+	prt     http.RoundTripper
+	ss      *snap.Snapshotter
+}
+
+func (s *bootstrappedServer) Close() {
+	s.storage.Close()
+}
+
+type bootstrappedStorage struct {
+	backend *bootstrappedBackend
+	wal     *bootstrappedWAL
+	st      v2store.Store
+}
+
+func (s *bootstrappedStorage) Close() {
+	s.backend.Close()
+}
+
+type bootstrappedBackend struct {
+	beHooks  *serverstorage.BackendHooks
+	be       backend.Backend
+	ci       cindex.ConsistentIndexer
+	beExist  bool
+	snapshot *raftpb.Snapshot
+}
+
+func (s *bootstrappedBackend) Close() {
+	s.be.Close()
+}
+
+type bootstrappedCluster struct {
+	remotes []*membership.Member
+	cl      *membership.RaftCluster
+	nodeID  types.ID
+}
+
+type bootstrappedRaft struct {
+	lg        *zap.Logger
+	heartbeat time.Duration
+
+	peers   []raft.Peer
+	config  *raft.Config
+	storage *raft.MemoryStorage
+}
+
+func bootstrapStorage(cfg config.ServerConfig, st v2store.Store, be *bootstrappedBackend, wal *bootstrappedWAL, cl *bootstrappedCluster) *bootstrappedStorage {
+	if wal == nil {
+		wal = bootstrapNewWAL(cfg, cl)
+	}
+
+	return &bootstrappedStorage{
+		backend: be,
+		st:      st,
+		wal:     wal,
+	}
+}
+
+func bootstrapSnapshot(cfg config.ServerConfig) *snap.Snapshotter {
+	if err := fileutil.TouchDirAll(cfg.Logger, cfg.SnapDir()); err != nil {
+		cfg.Logger.Fatal(
+			"failed to create snapshot directory",
+			zap.String("path", cfg.SnapDir()),
+			zap.Error(err),
+		)
+	}
+
+	if err := fileutil.RemoveMatchFile(cfg.Logger, cfg.SnapDir(), func(fileName string) bool {
+		return strings.HasPrefix(fileName, "tmp")
+	}); err != nil {
+		cfg.Logger.Error(
+			"failed to remove temp file(s) in snapshot directory",
+			zap.String("path", cfg.SnapDir()),
+			zap.Error(err),
+		)
+	}
+	return snap.New(cfg.Logger, cfg.SnapDir())
+}
+
+func bootstrapBackend(cfg config.ServerConfig, haveWAL bool, st v2store.Store, ss *snap.Snapshotter) (backend *bootstrappedBackend, err error) {
+	beExist := fileutil.Exist(cfg.BackendPath())
+	ci := cindex.NewConsistentIndex(nil)
+	beHooks := serverstorage.NewBackendHooks(cfg.Logger, ci)
+	be := serverstorage.OpenBackend(cfg, beHooks)
+	defer func() {
+		if err != nil && be != nil {
+			be.Close()
+		}
+	}()
+	ci.SetBackend(be)
+	schema.CreateMetaBucket(be.BatchTx())
+	if cfg.BootstrapDefragThresholdMegabytes != 0 {
+		err = maybeDefragBackend(cfg, be)
+		if err != nil {
+			return nil, err
+		}
+	}
+	cfg.Logger.Info("restore consistentIndex", zap.Uint64("index", ci.ConsistentIndex()))
+
+	// TODO(serathius): Implement schema setup in fresh storage
+	var snapshot *raftpb.Snapshot
+	if haveWAL {
+		snapshot, be, err = recoverSnapshot(cfg, st, be, beExist, beHooks, ci, ss)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if beExist {
+		s1, s2 := be.Size(), be.SizeInUse()
+		cfg.Logger.Info(
+			"recovered v3 backend",
+			zap.Int64("backend-size-bytes", s1),
+			zap.String("backend-size", humanize.Bytes(uint64(s1))),
+			zap.Int64("backend-size-in-use-bytes", s2),
+			zap.String("backend-size-in-use", humanize.Bytes(uint64(s2))),
+		)
+		if err = schema.Validate(cfg.Logger, be.ReadTx()); err != nil {
+			cfg.Logger.Error("Failed to validate schema", zap.Error(err))
+			return nil, err
+		}
+	}
+
+	return &bootstrappedBackend{
+		beHooks:  beHooks,
+		be:       be,
+		ci:       ci,
+		beExist:  beExist,
+		snapshot: snapshot,
+	}, nil
+}
+
+func maybeDefragBackend(cfg config.ServerConfig, be backend.Backend) error {
+	size := be.Size()
+	sizeInUse := be.SizeInUse()
+	freeableMemory := uint(size - sizeInUse)
+	thresholdBytes := cfg.BootstrapDefragThresholdMegabytes * 1024 * 1024
+	if freeableMemory < thresholdBytes {
+		cfg.Logger.Info("Skipping defragmentation",
+			zap.Int64("current-db-size-bytes", size),
+			zap.String("current-db-size", humanize.Bytes(uint64(size))),
+			zap.Int64("current-db-size-in-use-bytes", sizeInUse),
+			zap.String("current-db-size-in-use", humanize.Bytes(uint64(sizeInUse))),
+			zap.Uint("experimental-bootstrap-defrag-threshold-bytes", thresholdBytes),
+			zap.String("experimental-bootstrap-defrag-threshold", humanize.Bytes(uint64(thresholdBytes))),
+		)
+		return nil
+	}
+	return be.Defrag()
+}
+
+func bootstrapCluster(cfg config.ServerConfig, bwal *bootstrappedWAL, prt http.RoundTripper) (c *bootstrappedCluster, err error) {
+	switch {
+	case bwal == nil && !cfg.NewCluster:
+		c, err = bootstrapExistingClusterNoWAL(cfg, prt)
+	case bwal == nil && cfg.NewCluster:
+		c, err = bootstrapNewClusterNoWAL(cfg, prt)
+	case bwal != nil && bwal.haveWAL:
+		c, err = bootstrapClusterWithWAL(cfg, bwal.meta)
+	default:
+		return nil, fmt.Errorf("unsupported bootstrap config")
+	}
+	if err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+func bootstrapExistingClusterNoWAL(cfg config.ServerConfig, prt http.RoundTripper) (*bootstrappedCluster, error) {
+	if err := cfg.VerifyJoinExisting(); err != nil {
+		return nil, err
+	}
+	cl, err := membership.NewClusterFromURLsMap(cfg.Logger, cfg.InitialClusterToken, cfg.InitialPeerURLsMap, membership.WithMaxLearners(cfg.MaxLearners))
+	if err != nil {
+		return nil, err
+	}
+	existingCluster, gerr := GetClusterFromRemotePeers(cfg.Logger, getRemotePeerURLs(cl, cfg.Name), prt)
+	if gerr != nil {
+		return nil, fmt.Errorf("cannot fetch cluster info from peer urls: %w", gerr)
+	}
+	if err := membership.ValidateClusterAndAssignIDs(cfg.Logger, cl, existingCluster); err != nil {
+		return nil, fmt.Errorf("error validating peerURLs %s: %w", existingCluster, err)
+	}
+	if !isCompatibleWithCluster(cfg.Logger, cl, cl.MemberByName(cfg.Name).ID, prt, cfg.ReqTimeout()) {
+		return nil, fmt.Errorf("incompatible with current running cluster")
+	}
+	scaleUpLearners := false
+	if err := membership.ValidateMaxLearnerConfig(cfg.MaxLearners, existingCluster.Members(), scaleUpLearners); err != nil {
+		return nil, err
+	}
+	remotes := existingCluster.Members()
+	cl.SetID(types.ID(0), existingCluster.ID())
+	member := cl.MemberByName(cfg.Name)
+	return &bootstrappedCluster{
+		remotes: remotes,
+		cl:      cl,
+		nodeID:  member.ID,
+	}, nil
+}
+
+func bootstrapNewClusterNoWAL(cfg config.ServerConfig, prt http.RoundTripper) (*bootstrappedCluster, error) {
+	if err := cfg.VerifyBootstrap(); err != nil {
+		return nil, err
+	}
+	cl, err := membership.NewClusterFromURLsMap(cfg.Logger, cfg.InitialClusterToken, cfg.InitialPeerURLsMap, membership.WithMaxLearners(cfg.MaxLearners))
+	if err != nil {
+		return nil, err
+	}
+	m := cl.MemberByName(cfg.Name)
+	if isMemberBootstrapped(cfg.Logger, cl, cfg.Name, prt, cfg.BootstrapTimeoutEffective()) {
+		return nil, fmt.Errorf("member %s has already been bootstrapped", m.ID)
+	}
+	if cfg.ShouldDiscover() {
+		var str string
+		if cfg.DiscoveryURL != "" {
+			cfg.Logger.Warn("V2 discovery is deprecated!")
+			str, err = v2discovery.JoinCluster(cfg.Logger, cfg.DiscoveryURL, cfg.DiscoveryProxy, m.ID, cfg.InitialPeerURLsMap.String())
+		} else {
+			cfg.Logger.Info("Bootstrapping cluster using v3 discovery.")
+			str, err = v3discovery.JoinCluster(cfg.Logger, &cfg.DiscoveryCfg, m.ID, cfg.InitialPeerURLsMap.String())
+		}
+		if err != nil {
+			return nil, &servererrors.DiscoveryError{Op: "join", Err: err}
+		}
+		var urlsmap types.URLsMap
+		urlsmap, err = types.NewURLsMap(str)
+		if err != nil {
+			return nil, err
+		}
+		if config.CheckDuplicateURL(urlsmap) {
+			return nil, fmt.Errorf("discovery cluster %s has duplicate url", urlsmap)
+		}
+		if cl, err = membership.NewClusterFromURLsMap(cfg.Logger, cfg.InitialClusterToken, urlsmap, membership.WithMaxLearners(cfg.MaxLearners)); err != nil {
+			return nil, err
+		}
+	}
+	return &bootstrappedCluster{
+		remotes: nil,
+		cl:      cl,
+		nodeID:  m.ID,
+	}, nil
+}
+
+func bootstrapClusterWithWAL(cfg config.ServerConfig, meta *snapshotMetadata) (*bootstrappedCluster, error) {
+	if err := fileutil.IsDirWriteable(cfg.MemberDir()); err != nil {
+		return nil, fmt.Errorf("cannot write to member directory: %w", err)
+	}
+
+	if cfg.ShouldDiscover() {
+		cfg.Logger.Warn(
+			"discovery token is ignored since cluster already initialized; valid logs are found",
+			zap.String("wal-dir", cfg.WALDir()),
+		)
+	}
+	cl := membership.NewCluster(cfg.Logger, membership.WithMaxLearners(cfg.MaxLearners))
+
+	scaleUpLearners := false
+	if err := membership.ValidateMaxLearnerConfig(cfg.MaxLearners, cl.Members(), scaleUpLearners); err != nil {
+		return nil, err
+	}
+
+	cl.SetID(meta.nodeID, meta.clusterID)
+	return &bootstrappedCluster{
+		cl:     cl,
+		nodeID: meta.nodeID,
+	}, nil
+}
+
+func recoverSnapshot(cfg config.ServerConfig, st v2store.Store, be backend.Backend, beExist bool, beHooks *serverstorage.BackendHooks, ci cindex.ConsistentIndexer, ss *snap.Snapshotter) (*raftpb.Snapshot, backend.Backend, error) {
+	// Find a snapshot to start/restart a raft node
+	walSnaps, err := wal.ValidSnapshotEntries(cfg.Logger, cfg.WALDir())
+	if err != nil {
+		return nil, be, err
+	}
+	// snapshot files can be orphaned if etcd crashes after writing them but before writing the corresponding
+	// bwal log entries
+	snapshot, err := ss.LoadNewestAvailable(walSnaps)
+	if err != nil && !errors.Is(err, snap.ErrNoSnapshot) {
+		return nil, be, err
+	}
+
+	if snapshot != nil {
+		if err = st.Recovery(snapshot.Data); err != nil {
+			cfg.Logger.Panic("failed to recover from snapshot", zap.Error(err))
+		}
+
+		if err = serverstorage.AssertNoV2StoreContent(cfg.Logger, st, cfg.V2Deprecation); err != nil {
+			cfg.Logger.Error("illegal v2store content", zap.Error(err))
+			return nil, be, err
+		}
+
+		cfg.Logger.Info(
+			"recovered v2 store from snapshot",
+			zap.Uint64("snapshot-index", snapshot.Metadata.Index),
+			zap.String("snapshot-size", humanize.Bytes(uint64(snapshot.Size()))),
+		)
+
+		if be, err = serverstorage.RecoverSnapshotBackend(cfg, be, *snapshot, beExist, beHooks); err != nil {
+			cfg.Logger.Panic("failed to recover v3 backend from snapshot", zap.Error(err))
+		}
+		// A snapshot db may have already been recovered, and the old db should have
+		// already been closed in this case, so we should set the backend again.
+		ci.SetBackend(be)
+
+		if beExist {
+			// TODO: remove kvindex != 0 checking when we do not expect users to upgrade
+			// etcd from pre-3.0 release.
+			kvindex := ci.ConsistentIndex()
+			if kvindex < snapshot.Metadata.Index {
+				if kvindex != 0 {
+					return nil, be, fmt.Errorf("database file (%v index %d) does not match with snapshot (index %d)", cfg.BackendPath(), kvindex, snapshot.Metadata.Index)
+				}
+				cfg.Logger.Warn(
+					"consistent index was never saved",
+					zap.Uint64("snapshot-index", snapshot.Metadata.Index),
+				)
+			}
+		}
+	} else {
+		cfg.Logger.Info("No snapshot found. Recovering WAL from scratch!")
+	}
+	return snapshot, be, nil
+}
+
+func (c *bootstrappedCluster) Finalize(cfg config.ServerConfig, s *bootstrappedStorage) error {
+	if !s.wal.haveWAL {
+		c.cl.SetID(c.nodeID, c.cl.ID())
+	}
+	c.cl.SetStore(s.st)
+	c.cl.SetBackend(schema.NewMembershipBackend(cfg.Logger, s.backend.be))
+
+	// Workaround the issues which have already been affected
+	// by https://github.com/etcd-io/etcd/issues/19557.
+	c.cl.SyncLearnerPromotionIfNeeded()
+
+	if s.wal.haveWAL {
+		c.cl.Recover(api.UpdateCapability)
+		if c.databaseFileMissing(s) {
+			bepath := cfg.BackendPath()
+			os.RemoveAll(bepath)
+			return fmt.Errorf("database file (%v) of the backend is missing", bepath)
+		}
+	}
+	scaleUpLearners := false
+	return membership.ValidateMaxLearnerConfig(cfg.MaxLearners, c.cl.Members(), scaleUpLearners)
+}
+
+func (c *bootstrappedCluster) databaseFileMissing(s *bootstrappedStorage) bool {
+	v3Cluster := c.cl.Version() != nil && !c.cl.Version().LessThan(semver.Version{Major: 3})
+	return v3Cluster && !s.backend.beExist
+}
+
+func bootstrapRaft(cfg config.ServerConfig, cluster *bootstrappedCluster, bwal *bootstrappedWAL) *bootstrappedRaft {
+	switch {
+	case !bwal.haveWAL && !cfg.NewCluster:
+		return bootstrapRaftFromCluster(cfg, cluster.cl, nil, bwal)
+	case !bwal.haveWAL && cfg.NewCluster:
+		return bootstrapRaftFromCluster(cfg, cluster.cl, cluster.cl.MemberIDs(), bwal)
+	case bwal.haveWAL:
+		return bootstrapRaftFromWAL(cfg, bwal)
+	default:
+		cfg.Logger.Panic("unsupported bootstrap config")
+		return nil
+	}
+}
+
+func bootstrapRaftFromCluster(cfg config.ServerConfig, cl *membership.RaftCluster, ids []types.ID, bwal *bootstrappedWAL) *bootstrappedRaft {
+	member := cl.MemberByName(cfg.Name)
+	peers := make([]raft.Peer, len(ids))
+	for i, id := range ids {
+		var ctx []byte
+		ctx, err := json.Marshal((*cl).Member(id))
+		if err != nil {
+			cfg.Logger.Panic("failed to marshal member", zap.Error(err))
+		}
+		peers[i] = raft.Peer{ID: uint64(id), Context: ctx}
+	}
+	cfg.Logger.Info(
+		"starting local member",
+		zap.String("local-member-id", member.ID.String()),
+		zap.String("cluster-id", cl.ID().String()),
+	)
+	s := bwal.MemoryStorage()
+	return &bootstrappedRaft{
+		lg:        cfg.Logger,
+		heartbeat: time.Duration(cfg.TickMs) * time.Millisecond,
+		config:    raftConfig(cfg, uint64(member.ID), s),
+		peers:     peers,
+		storage:   s,
+	}
+}
+
+func bootstrapRaftFromWAL(cfg config.ServerConfig, bwal *bootstrappedWAL) *bootstrappedRaft {
+	s := bwal.MemoryStorage()
+	return &bootstrappedRaft{
+		lg:        cfg.Logger,
+		heartbeat: time.Duration(cfg.TickMs) * time.Millisecond,
+		config:    raftConfig(cfg, uint64(bwal.meta.nodeID), s),
+		storage:   s,
+	}
+}
+
+func raftConfig(cfg config.ServerConfig, id uint64, s *raft.MemoryStorage) *raft.Config {
+	return &raft.Config{
+		ID:              id,
+		ElectionTick:    cfg.ElectionTicks,
+		HeartbeatTick:   1,
+		Storage:         s,
+		MaxSizePerMsg:   maxSizePerMsg,
+		MaxInflightMsgs: maxInflightMsgs,
+		CheckQuorum:     true,
+		PreVote:         cfg.PreVote,
+		Logger:          NewRaftLoggerZap(cfg.Logger.Named("raft")),
+	}
+}
+
+func (b *bootstrappedRaft) newRaftNode(ss *snap.Snapshotter, wal *wal.WAL, cl *membership.RaftCluster) *raftNode {
+	var n raft.Node
+	if len(b.peers) == 0 {
+		n = raft.RestartNode(b.config)
+	} else {
+		n = raft.StartNode(b.config, b.peers)
+	}
+	raftStatusMu.Lock()
+	raftStatus = n.Status
+	raftStatusMu.Unlock()
+	return newRaftNode(
+		raftNodeConfig{
+			lg:          b.lg,
+			isIDRemoved: func(id uint64) bool { return cl.IsIDRemoved(types.ID(id)) },
+			Node:        n,
+			heartbeat:   b.heartbeat,
+			raftStorage: b.storage,
+			storage:     serverstorage.NewStorage(b.lg, wal, ss),
+		},
+	)
+}
+
+func bootstrapWALFromSnapshot(cfg config.ServerConfig, snapshot *raftpb.Snapshot, ci cindex.ConsistentIndexer) *bootstrappedWAL {
+	wal, st, ents, snap, meta := openWALFromSnapshot(cfg, snapshot)
+	bwal := &bootstrappedWAL{
+		lg:       cfg.Logger,
+		w:        wal,
+		st:       st,
+		ents:     ents,
+		snapshot: snap,
+		meta:     meta,
+		haveWAL:  true,
+	}
+
+	if cfg.ForceNewCluster {
+		consistentIndex := ci.ConsistentIndex()
+		oldCommitIndex := bwal.st.Commit
+		// If only `HardState.Commit` increases, HardState won't be persisted
+		// to disk, even though the committed entries might have already been
+		// applied. This can result in consistent_index > CommitIndex.
+		//
+		// When restarting etcd with `--force-new-cluster`, all uncommitted
+		// entries are dropped. To avoid losing entries that were actually
+		// committed, we reset Commit to max(HardState.Commit, consistent_index).
+		//
+		// See: https://github.com/etcd-io/raft/pull/300 for more details.
+		bwal.st.Commit = max(oldCommitIndex, consistentIndex)
+
+		// discard the previously uncommitted entries
+		bwal.ents = bwal.CommitedEntries()
+		entries := bwal.NewConfigChangeEntries()
+		// force commit config change entries
+		bwal.AppendAndCommitEntries(entries)
+		cfg.Logger.Info(
+			"forcing restart member",
+			zap.String("cluster-id", meta.clusterID.String()),
+			zap.String("local-member-id", meta.nodeID.String()),
+			zap.Uint64("wal-commit-index", oldCommitIndex),
+			zap.Uint64("commit-index", bwal.st.Commit),
+		)
+	} else {
+		cfg.Logger.Info(
+			"restarting local member",
+			zap.String("cluster-id", meta.clusterID.String()),
+			zap.String("local-member-id", meta.nodeID.String()),
+			zap.Uint64("commit-index", bwal.st.Commit),
+		)
+	}
+	return bwal
+}
+
+// openWALFromSnapshot reads the WAL at the given snap and returns the wal, its latest HardState and cluster ID, and all entries that appear
+// after the position of the given snap in the WAL.
+// The snap must have been previously saved to the WAL, or this call will panic.
+func openWALFromSnapshot(cfg config.ServerConfig, snapshot *raftpb.Snapshot) (*wal.WAL, *raftpb.HardState, []raftpb.Entry, *raftpb.Snapshot, *snapshotMetadata) {
+	var walsnap walpb.Snapshot
+	if snapshot != nil {
+		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
+	}
+	repaired := false
+	for {
+		w, err := wal.Open(cfg.Logger, cfg.WALDir(), walsnap)
+		if err != nil {
+			cfg.Logger.Fatal("failed to open WAL", zap.Error(err))
+		}
+		if cfg.UnsafeNoFsync {
+			w.SetUnsafeNoFsync()
+		}
+		wmetadata, st, ents, err := w.ReadAll()
+		if err != nil {
+			w.Close()
+			// we can only repair ErrUnexpectedEOF and we never repair twice.
+			if repaired || !errors.Is(err, io.ErrUnexpectedEOF) {
+				cfg.Logger.Fatal("failed to read WAL, cannot be repaired", zap.Error(err))
+			}
+			if !wal.Repair(cfg.Logger, cfg.WALDir()) {
+				cfg.Logger.Fatal("failed to repair WAL", zap.Error(err))
+			} else {
+				cfg.Logger.Info("repaired WAL", zap.Error(err))
+				repaired = true
+			}
+			continue
+		}
+		var metadata etcdserverpb.Metadata
+		pbutil.MustUnmarshal(&metadata, wmetadata)
+		id := types.ID(metadata.NodeID)
+		cid := types.ID(metadata.ClusterID)
+		meta := &snapshotMetadata{clusterID: cid, nodeID: id}
+		return w, &st, ents, snapshot, meta
+	}
+}
+
+type snapshotMetadata struct {
+	nodeID, clusterID types.ID
+}
+
+func bootstrapNewWAL(cfg config.ServerConfig, cl *bootstrappedCluster) *bootstrappedWAL {
+	metadata := pbutil.MustMarshal(
+		&etcdserverpb.Metadata{
+			NodeID:    uint64(cl.nodeID),
+			ClusterID: uint64(cl.cl.ID()),
+		},
+	)
+	w, err := wal.Create(cfg.Logger, cfg.WALDir(), metadata)
+	if err != nil {
+		cfg.Logger.Panic("failed to create WAL", zap.Error(err))
+	}
+	if cfg.UnsafeNoFsync {
+		w.SetUnsafeNoFsync()
+	}
+	return &bootstrappedWAL{
+		lg: cfg.Logger,
+		w:  w,
+	}
+}
+
+type bootstrappedWAL struct {
+	lg *zap.Logger
+
+	haveWAL  bool
+	w        *wal.WAL
+	st       *raftpb.HardState
+	ents     []raftpb.Entry
+	snapshot *raftpb.Snapshot
+	meta     *snapshotMetadata
+}
+
+func (wal *bootstrappedWAL) MemoryStorage() *raft.MemoryStorage {
+	s := raft.NewMemoryStorage()
+	if wal.snapshot != nil {
+		s.ApplySnapshot(*wal.snapshot)
+	}
+	if wal.st != nil {
+		s.SetHardState(*wal.st)
+	}
+	if len(wal.ents) != 0 {
+		s.Append(wal.ents)
+	}
+	return s
+}
+
+func (wal *bootstrappedWAL) CommitedEntries() []raftpb.Entry {
+	for i, ent := range wal.ents {
+		if ent.Index > wal.st.Commit {
+			wal.lg.Info(
+				"discarding uncommitted WAL entries",
+				zap.Uint64("entry-index", ent.Index),
+				zap.Uint64("commit-index-from-wal", wal.st.Commit),
+				zap.Int("number-of-discarded-entries", len(wal.ents)-i),
+			)
+			return wal.ents[:i]
+		}
+	}
+	return wal.ents
+}
+
+func (wal *bootstrappedWAL) NewConfigChangeEntries() []raftpb.Entry {
+	return serverstorage.CreateConfigChangeEnts(
+		wal.lg,
+		serverstorage.GetEffectiveNodeIDsFromWALEntries(wal.lg, wal.snapshot, wal.ents),
+		uint64(wal.meta.nodeID),
+		wal.st.Term,
+		wal.st.Commit,
+	)
+}
+
+func (wal *bootstrappedWAL) AppendAndCommitEntries(ents []raftpb.Entry) {
+	wal.ents = append(wal.ents, ents...)
+	err := wal.w.Save(raftpb.HardState{}, ents)
+	if err != nil {
+		wal.lg.Fatal("failed to save hard state and entries", zap.Error(err))
+	}
+	if len(wal.ents) != 0 {
+		wal.st.Commit = wal.ents[len(wal.ents)-1].Index
+	}
+}