diff --git a/vendor/go.etcd.io/etcd/embed/etcd.go b/vendor/go.etcd.io/etcd/embed/etcd.go
new file mode 100644
index 0000000..ac7dbc9
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/embed/etcd.go
@@ -0,0 +1,829 @@
+// Copyright 2016 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 embed
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"io/ioutil"
+	defaultLog "log"
+	"net"
+	"net/http"
+	"net/url"
+	"runtime"
+	"sort"
+	"strconv"
+	"sync"
+	"time"
+
+	"go.etcd.io/etcd/etcdserver"
+	"go.etcd.io/etcd/etcdserver/api/etcdhttp"
+	"go.etcd.io/etcd/etcdserver/api/rafthttp"
+	"go.etcd.io/etcd/etcdserver/api/v2http"
+	"go.etcd.io/etcd/etcdserver/api/v2v3"
+	"go.etcd.io/etcd/etcdserver/api/v3client"
+	"go.etcd.io/etcd/etcdserver/api/v3rpc"
+	"go.etcd.io/etcd/pkg/debugutil"
+	runtimeutil "go.etcd.io/etcd/pkg/runtime"
+	"go.etcd.io/etcd/pkg/transport"
+	"go.etcd.io/etcd/pkg/types"
+	"go.etcd.io/etcd/version"
+
+	"github.com/coreos/pkg/capnslog"
+	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
+	"github.com/soheilhy/cmux"
+	"go.uber.org/zap"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/keepalive"
+)
+
+var plog = capnslog.NewPackageLogger("go.etcd.io/etcd", "embed")
+
+const (
+	// internal fd usage includes disk usage and transport usage.
+	// To read/write snapshot, snap pkg needs 1. In normal case, wal pkg needs
+	// at most 2 to read/lock/write WALs. One case that it needs to 2 is to
+	// read all logs after some snapshot index, which locates at the end of
+	// the second last and the head of the last. For purging, it needs to read
+	// directory, so it needs 1. For fd monitor, it needs 1.
+	// For transport, rafthttp builds two long-polling connections and at most
+	// four temporary connections with each member. There are at most 9 members
+	// in a cluster, so it should reserve 96.
+	// For the safety, we set the total reserved number to 150.
+	reservedInternalFDNum = 150
+)
+
+// Etcd contains a running etcd server and its listeners.
+type Etcd struct {
+	Peers   []*peerListener
+	Clients []net.Listener
+	// a map of contexts for the servers that serves client requests.
+	sctxs            map[string]*serveCtx
+	metricsListeners []net.Listener
+
+	Server *etcdserver.EtcdServer
+
+	cfg   Config
+	stopc chan struct{}
+	errc  chan error
+
+	closeOnce sync.Once
+}
+
+type peerListener struct {
+	net.Listener
+	serve func() error
+	close func(context.Context) error
+}
+
+// StartEtcd launches the etcd server and HTTP handlers for client/server communication.
+// The returned Etcd.Server is not guaranteed to have joined the cluster. Wait
+// on the Etcd.Server.ReadyNotify() channel to know when it completes and is ready for use.
+func StartEtcd(inCfg *Config) (e *Etcd, err error) {
+	if err = inCfg.Validate(); err != nil {
+		return nil, err
+	}
+	serving := false
+	e = &Etcd{cfg: *inCfg, stopc: make(chan struct{})}
+	cfg := &e.cfg
+	defer func() {
+		if e == nil || err == nil {
+			return
+		}
+		if !serving {
+			// errored before starting gRPC server for serveCtx.serversC
+			for _, sctx := range e.sctxs {
+				close(sctx.serversC)
+			}
+		}
+		e.Close()
+		e = nil
+	}()
+
+	if e.cfg.logger != nil {
+		e.cfg.logger.Info(
+			"configuring peer listeners",
+			zap.Strings("listen-peer-urls", e.cfg.getLPURLs()),
+		)
+	}
+	if e.Peers, err = configurePeerListeners(cfg); err != nil {
+		return e, err
+	}
+
+	if e.cfg.logger != nil {
+		e.cfg.logger.Info(
+			"configuring client listeners",
+			zap.Strings("listen-client-urls", e.cfg.getLCURLs()),
+		)
+	}
+	if e.sctxs, err = configureClientListeners(cfg); err != nil {
+		return e, err
+	}
+
+	for _, sctx := range e.sctxs {
+		e.Clients = append(e.Clients, sctx.l)
+	}
+
+	var (
+		urlsmap types.URLsMap
+		token   string
+	)
+	memberInitialized := true
+	if !isMemberInitialized(cfg) {
+		memberInitialized = false
+		urlsmap, token, err = cfg.PeerURLsMapAndToken("etcd")
+		if err != nil {
+			return e, fmt.Errorf("error setting up initial cluster: %v", err)
+		}
+	}
+
+	// AutoCompactionRetention defaults to "0" if not set.
+	if len(cfg.AutoCompactionRetention) == 0 {
+		cfg.AutoCompactionRetention = "0"
+	}
+	autoCompactionRetention, err := parseCompactionRetention(cfg.AutoCompactionMode, cfg.AutoCompactionRetention)
+	if err != nil {
+		return e, err
+	}
+
+	backendFreelistType := parseBackendFreelistType(cfg.ExperimentalBackendFreelistType)
+
+	srvcfg := etcdserver.ServerConfig{
+		Name:                       cfg.Name,
+		ClientURLs:                 cfg.ACUrls,
+		PeerURLs:                   cfg.APUrls,
+		DataDir:                    cfg.Dir,
+		DedicatedWALDir:            cfg.WalDir,
+		SnapshotCount:              cfg.SnapshotCount,
+		SnapshotCatchUpEntries:     cfg.SnapshotCatchUpEntries,
+		MaxSnapFiles:               cfg.MaxSnapFiles,
+		MaxWALFiles:                cfg.MaxWalFiles,
+		InitialPeerURLsMap:         urlsmap,
+		InitialClusterToken:        token,
+		DiscoveryURL:               cfg.Durl,
+		DiscoveryProxy:             cfg.Dproxy,
+		NewCluster:                 cfg.IsNewCluster(),
+		PeerTLSInfo:                cfg.PeerTLSInfo,
+		TickMs:                     cfg.TickMs,
+		ElectionTicks:              cfg.ElectionTicks(),
+		InitialElectionTickAdvance: cfg.InitialElectionTickAdvance,
+		AutoCompactionRetention:    autoCompactionRetention,
+		AutoCompactionMode:         cfg.AutoCompactionMode,
+		QuotaBackendBytes:          cfg.QuotaBackendBytes,
+		BackendBatchLimit:          cfg.BackendBatchLimit,
+		BackendFreelistType:        backendFreelistType,
+		BackendBatchInterval:       cfg.BackendBatchInterval,
+		MaxTxnOps:                  cfg.MaxTxnOps,
+		MaxRequestBytes:            cfg.MaxRequestBytes,
+		StrictReconfigCheck:        cfg.StrictReconfigCheck,
+		ClientCertAuthEnabled:      cfg.ClientTLSInfo.ClientCertAuth,
+		AuthToken:                  cfg.AuthToken,
+		BcryptCost:                 cfg.BcryptCost,
+		CORS:                       cfg.CORS,
+		HostWhitelist:              cfg.HostWhitelist,
+		InitialCorruptCheck:        cfg.ExperimentalInitialCorruptCheck,
+		CorruptCheckTime:           cfg.ExperimentalCorruptCheckTime,
+		PreVote:                    cfg.PreVote,
+		Logger:                     cfg.logger,
+		LoggerConfig:               cfg.loggerConfig,
+		LoggerCore:                 cfg.loggerCore,
+		LoggerWriteSyncer:          cfg.loggerWriteSyncer,
+		Debug:                      cfg.Debug,
+		ForceNewCluster:            cfg.ForceNewCluster,
+		EnableGRPCGateway:          cfg.EnableGRPCGateway,
+		EnableLeaseCheckpoint:      cfg.ExperimentalEnableLeaseCheckpoint,
+		CompactionBatchLimit:       cfg.ExperimentalCompactionBatchLimit,
+	}
+	print(e.cfg.logger, *cfg, srvcfg, memberInitialized)
+	if e.Server, err = etcdserver.NewServer(srvcfg); err != nil {
+		return e, err
+	}
+
+	// buffer channel so goroutines on closed connections won't wait forever
+	e.errc = make(chan error, len(e.Peers)+len(e.Clients)+2*len(e.sctxs))
+
+	// newly started member ("memberInitialized==false")
+	// does not need corruption check
+	if memberInitialized {
+		if err = e.Server.CheckInitialHashKV(); err != nil {
+			// set "EtcdServer" to nil, so that it does not block on "EtcdServer.Close()"
+			// (nothing to close since rafthttp transports have not been started)
+			e.Server = nil
+			return e, err
+		}
+	}
+	e.Server.Start()
+
+	if err = e.servePeers(); err != nil {
+		return e, err
+	}
+	if err = e.serveClients(); err != nil {
+		return e, err
+	}
+	if err = e.serveMetrics(); err != nil {
+		return e, err
+	}
+
+	if e.cfg.logger != nil {
+		e.cfg.logger.Info(
+			"now serving peer/client/metrics",
+			zap.String("local-member-id", e.Server.ID().String()),
+			zap.Strings("initial-advertise-peer-urls", e.cfg.getAPURLs()),
+			zap.Strings("listen-peer-urls", e.cfg.getLPURLs()),
+			zap.Strings("advertise-client-urls", e.cfg.getACURLs()),
+			zap.Strings("listen-client-urls", e.cfg.getLCURLs()),
+			zap.Strings("listen-metrics-urls", e.cfg.getMetricsURLs()),
+		)
+	}
+	serving = true
+	return e, nil
+}
+
+func print(lg *zap.Logger, ec Config, sc etcdserver.ServerConfig, memberInitialized bool) {
+	// TODO: remove this after dropping "capnslog"
+	if lg == nil {
+		plog.Infof("name = %s", ec.Name)
+		if sc.ForceNewCluster {
+			plog.Infof("force new cluster")
+		}
+		plog.Infof("data dir = %s", sc.DataDir)
+		plog.Infof("member dir = %s", sc.MemberDir())
+		if sc.DedicatedWALDir != "" {
+			plog.Infof("dedicated WAL dir = %s", sc.DedicatedWALDir)
+		}
+		plog.Infof("heartbeat = %dms", sc.TickMs)
+		plog.Infof("election = %dms", sc.ElectionTicks*int(sc.TickMs))
+		plog.Infof("snapshot count = %d", sc.SnapshotCount)
+		if len(sc.DiscoveryURL) != 0 {
+			plog.Infof("discovery URL= %s", sc.DiscoveryURL)
+			if len(sc.DiscoveryProxy) != 0 {
+				plog.Infof("discovery proxy = %s", sc.DiscoveryProxy)
+			}
+		}
+		plog.Infof("advertise client URLs = %s", sc.ClientURLs)
+		if memberInitialized {
+			plog.Infof("initial advertise peer URLs = %s", sc.PeerURLs)
+			plog.Infof("initial cluster = %s", sc.InitialPeerURLsMap)
+		}
+	} else {
+		cors := make([]string, 0, len(ec.CORS))
+		for v := range ec.CORS {
+			cors = append(cors, v)
+		}
+		sort.Strings(cors)
+
+		hss := make([]string, 0, len(ec.HostWhitelist))
+		for v := range ec.HostWhitelist {
+			hss = append(hss, v)
+		}
+		sort.Strings(hss)
+
+		quota := ec.QuotaBackendBytes
+		if quota == 0 {
+			quota = etcdserver.DefaultQuotaBytes
+		}
+
+		lg.Info(
+			"starting an etcd server",
+			zap.String("etcd-version", version.Version),
+			zap.String("git-sha", version.GitSHA),
+			zap.String("go-version", runtime.Version()),
+			zap.String("go-os", runtime.GOOS),
+			zap.String("go-arch", runtime.GOARCH),
+			zap.Int("max-cpu-set", runtime.GOMAXPROCS(0)),
+			zap.Int("max-cpu-available", runtime.NumCPU()),
+			zap.Bool("member-initialized", memberInitialized),
+			zap.String("name", sc.Name),
+			zap.String("data-dir", sc.DataDir),
+			zap.String("wal-dir", ec.WalDir),
+			zap.String("wal-dir-dedicated", sc.DedicatedWALDir),
+			zap.String("member-dir", sc.MemberDir()),
+			zap.Bool("force-new-cluster", sc.ForceNewCluster),
+			zap.String("heartbeat-interval", fmt.Sprintf("%v", time.Duration(sc.TickMs)*time.Millisecond)),
+			zap.String("election-timeout", fmt.Sprintf("%v", time.Duration(sc.ElectionTicks*int(sc.TickMs))*time.Millisecond)),
+			zap.Bool("initial-election-tick-advance", sc.InitialElectionTickAdvance),
+			zap.Uint64("snapshot-count", sc.SnapshotCount),
+			zap.Uint64("snapshot-catchup-entries", sc.SnapshotCatchUpEntries),
+			zap.Strings("initial-advertise-peer-urls", ec.getAPURLs()),
+			zap.Strings("listen-peer-urls", ec.getLPURLs()),
+			zap.Strings("advertise-client-urls", ec.getACURLs()),
+			zap.Strings("listen-client-urls", ec.getLCURLs()),
+			zap.Strings("listen-metrics-urls", ec.getMetricsURLs()),
+			zap.Strings("cors", cors),
+			zap.Strings("host-whitelist", hss),
+			zap.String("initial-cluster", sc.InitialPeerURLsMap.String()),
+			zap.String("initial-cluster-state", ec.ClusterState),
+			zap.String("initial-cluster-token", sc.InitialClusterToken),
+			zap.Int64("quota-size-bytes", quota),
+			zap.Bool("pre-vote", sc.PreVote),
+			zap.Bool("initial-corrupt-check", sc.InitialCorruptCheck),
+			zap.String("corrupt-check-time-interval", sc.CorruptCheckTime.String()),
+			zap.String("auto-compaction-mode", sc.AutoCompactionMode),
+			zap.Duration("auto-compaction-retention", sc.AutoCompactionRetention),
+			zap.String("auto-compaction-interval", sc.AutoCompactionRetention.String()),
+			zap.String("discovery-url", sc.DiscoveryURL),
+			zap.String("discovery-proxy", sc.DiscoveryProxy),
+		)
+	}
+}
+
+// Config returns the current configuration.
+func (e *Etcd) Config() Config {
+	return e.cfg
+}
+
+// Close gracefully shuts down all servers/listeners.
+// Client requests will be terminated with request timeout.
+// After timeout, enforce remaning requests be closed immediately.
+func (e *Etcd) Close() {
+	fields := []zap.Field{
+		zap.String("name", e.cfg.Name),
+		zap.String("data-dir", e.cfg.Dir),
+		zap.Strings("advertise-peer-urls", e.cfg.getAPURLs()),
+		zap.Strings("advertise-client-urls", e.cfg.getACURLs()),
+	}
+	lg := e.GetLogger()
+	if lg != nil {
+		lg.Info("closing etcd server", fields...)
+	}
+	defer func() {
+		if lg != nil {
+			lg.Info("closed etcd server", fields...)
+			lg.Sync()
+		}
+	}()
+
+	e.closeOnce.Do(func() { close(e.stopc) })
+
+	// close client requests with request timeout
+	timeout := 2 * time.Second
+	if e.Server != nil {
+		timeout = e.Server.Cfg.ReqTimeout()
+	}
+	for _, sctx := range e.sctxs {
+		for ss := range sctx.serversC {
+			ctx, cancel := context.WithTimeout(context.Background(), timeout)
+			stopServers(ctx, ss)
+			cancel()
+		}
+	}
+
+	for _, sctx := range e.sctxs {
+		sctx.cancel()
+	}
+
+	for i := range e.Clients {
+		if e.Clients[i] != nil {
+			e.Clients[i].Close()
+		}
+	}
+
+	for i := range e.metricsListeners {
+		e.metricsListeners[i].Close()
+	}
+
+	// close rafthttp transports
+	if e.Server != nil {
+		e.Server.Stop()
+	}
+
+	// close all idle connections in peer handler (wait up to 1-second)
+	for i := range e.Peers {
+		if e.Peers[i] != nil && e.Peers[i].close != nil {
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+			e.Peers[i].close(ctx)
+			cancel()
+		}
+	}
+}
+
+func stopServers(ctx context.Context, ss *servers) {
+	shutdownNow := func() {
+		// first, close the http.Server
+		ss.http.Shutdown(ctx)
+		// then close grpc.Server; cancels all active RPCs
+		ss.grpc.Stop()
+	}
+
+	// do not grpc.Server.GracefulStop with TLS enabled etcd server
+	// See https://github.com/grpc/grpc-go/issues/1384#issuecomment-317124531
+	// and https://github.com/etcd-io/etcd/issues/8916
+	if ss.secure {
+		shutdownNow()
+		return
+	}
+
+	ch := make(chan struct{})
+	go func() {
+		defer close(ch)
+		// close listeners to stop accepting new connections,
+		// will block on any existing transports
+		ss.grpc.GracefulStop()
+	}()
+
+	// wait until all pending RPCs are finished
+	select {
+	case <-ch:
+	case <-ctx.Done():
+		// took too long, manually close open transports
+		// e.g. watch streams
+		shutdownNow()
+
+		// concurrent GracefulStop should be interrupted
+		<-ch
+	}
+}
+
+func (e *Etcd) Err() <-chan error { return e.errc }
+
+func configurePeerListeners(cfg *Config) (peers []*peerListener, err error) {
+	if err = updateCipherSuites(&cfg.PeerTLSInfo, cfg.CipherSuites); err != nil {
+		return nil, err
+	}
+	if err = cfg.PeerSelfCert(); err != nil {
+		if cfg.logger != nil {
+			cfg.logger.Fatal("failed to get peer self-signed certs", zap.Error(err))
+		} else {
+			plog.Fatalf("could not get certs (%v)", err)
+		}
+	}
+	if !cfg.PeerTLSInfo.Empty() {
+		if cfg.logger != nil {
+			cfg.logger.Info(
+				"starting with peer TLS",
+				zap.String("tls-info", fmt.Sprintf("%+v", cfg.PeerTLSInfo)),
+				zap.Strings("cipher-suites", cfg.CipherSuites),
+			)
+		} else {
+			plog.Infof("peerTLS: %s", cfg.PeerTLSInfo)
+		}
+	}
+
+	peers = make([]*peerListener, len(cfg.LPUrls))
+	defer func() {
+		if err == nil {
+			return
+		}
+		for i := range peers {
+			if peers[i] != nil && peers[i].close != nil {
+				if cfg.logger != nil {
+					cfg.logger.Warn(
+						"closing peer listener",
+						zap.String("address", cfg.LPUrls[i].String()),
+						zap.Error(err),
+					)
+				} else {
+					plog.Info("stopping listening for peers on ", cfg.LPUrls[i].String())
+				}
+				ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+				peers[i].close(ctx)
+				cancel()
+			}
+		}
+	}()
+
+	for i, u := range cfg.LPUrls {
+		if u.Scheme == "http" {
+			if !cfg.PeerTLSInfo.Empty() {
+				if cfg.logger != nil {
+					cfg.logger.Warn("scheme is HTTP while key and cert files are present; ignoring key and cert files", zap.String("peer-url", u.String()))
+				} else {
+					plog.Warningf("The scheme of peer url %s is HTTP while peer key/cert files are presented. Ignored peer key/cert files.", u.String())
+				}
+			}
+			if cfg.PeerTLSInfo.ClientCertAuth {
+				if cfg.logger != nil {
+					cfg.logger.Warn("scheme is HTTP while --peer-client-cert-auth is enabled; ignoring client cert auth for this URL", zap.String("peer-url", u.String()))
+				} else {
+					plog.Warningf("The scheme of peer url %s is HTTP while client cert auth (--peer-client-cert-auth) is enabled. Ignored client cert auth for this url.", u.String())
+				}
+			}
+		}
+		peers[i] = &peerListener{close: func(context.Context) error { return nil }}
+		peers[i].Listener, err = rafthttp.NewListener(u, &cfg.PeerTLSInfo)
+		if err != nil {
+			return nil, err
+		}
+		// once serve, overwrite with 'http.Server.Shutdown'
+		peers[i].close = func(context.Context) error {
+			return peers[i].Listener.Close()
+		}
+	}
+	return peers, nil
+}
+
+// configure peer handlers after rafthttp.Transport started
+func (e *Etcd) servePeers() (err error) {
+	ph := etcdhttp.NewPeerHandler(e.GetLogger(), e.Server)
+	var peerTLScfg *tls.Config
+	if !e.cfg.PeerTLSInfo.Empty() {
+		if peerTLScfg, err = e.cfg.PeerTLSInfo.ServerConfig(); err != nil {
+			return err
+		}
+	}
+
+	for _, p := range e.Peers {
+		u := p.Listener.Addr().String()
+		gs := v3rpc.Server(e.Server, peerTLScfg)
+		m := cmux.New(p.Listener)
+		go gs.Serve(m.Match(cmux.HTTP2()))
+		srv := &http.Server{
+			Handler:     grpcHandlerFunc(gs, ph),
+			ReadTimeout: 5 * time.Minute,
+			ErrorLog:    defaultLog.New(ioutil.Discard, "", 0), // do not log user error
+		}
+		go srv.Serve(m.Match(cmux.Any()))
+		p.serve = func() error { return m.Serve() }
+		p.close = func(ctx context.Context) error {
+			// gracefully shutdown http.Server
+			// close open listeners, idle connections
+			// until context cancel or time-out
+			if e.cfg.logger != nil {
+				e.cfg.logger.Info(
+					"stopping serving peer traffic",
+					zap.String("address", u),
+				)
+			}
+			stopServers(ctx, &servers{secure: peerTLScfg != nil, grpc: gs, http: srv})
+			if e.cfg.logger != nil {
+				e.cfg.logger.Info(
+					"stopped serving peer traffic",
+					zap.String("address", u),
+				)
+			}
+			return nil
+		}
+	}
+
+	// start peer servers in a goroutine
+	for _, pl := range e.Peers {
+		go func(l *peerListener) {
+			u := l.Addr().String()
+			if e.cfg.logger != nil {
+				e.cfg.logger.Info(
+					"serving peer traffic",
+					zap.String("address", u),
+				)
+			} else {
+				plog.Info("listening for peers on ", u)
+			}
+			e.errHandler(l.serve())
+		}(pl)
+	}
+	return nil
+}
+
+func configureClientListeners(cfg *Config) (sctxs map[string]*serveCtx, err error) {
+	if err = updateCipherSuites(&cfg.ClientTLSInfo, cfg.CipherSuites); err != nil {
+		return nil, err
+	}
+	if err = cfg.ClientSelfCert(); err != nil {
+		if cfg.logger != nil {
+			cfg.logger.Fatal("failed to get client self-signed certs", zap.Error(err))
+		} else {
+			plog.Fatalf("could not get certs (%v)", err)
+		}
+	}
+	if cfg.EnablePprof {
+		if cfg.logger != nil {
+			cfg.logger.Info("pprof is enabled", zap.String("path", debugutil.HTTPPrefixPProf))
+		} else {
+			plog.Infof("pprof is enabled under %s", debugutil.HTTPPrefixPProf)
+		}
+	}
+
+	sctxs = make(map[string]*serveCtx)
+	for _, u := range cfg.LCUrls {
+		sctx := newServeCtx(cfg.logger)
+		if u.Scheme == "http" || u.Scheme == "unix" {
+			if !cfg.ClientTLSInfo.Empty() {
+				if cfg.logger != nil {
+					cfg.logger.Warn("scheme is HTTP while key and cert files are present; ignoring key and cert files", zap.String("client-url", u.String()))
+				} else {
+					plog.Warningf("The scheme of client url %s is HTTP while peer key/cert files are presented. Ignored key/cert files.", u.String())
+				}
+			}
+			if cfg.ClientTLSInfo.ClientCertAuth {
+				if cfg.logger != nil {
+					cfg.logger.Warn("scheme is HTTP while --client-cert-auth is enabled; ignoring client cert auth for this URL", zap.String("client-url", u.String()))
+				} else {
+					plog.Warningf("The scheme of client url %s is HTTP while client cert auth (--client-cert-auth) is enabled. Ignored client cert auth for this url.", u.String())
+				}
+			}
+		}
+		if (u.Scheme == "https" || u.Scheme == "unixs") && cfg.ClientTLSInfo.Empty() {
+			return nil, fmt.Errorf("TLS key/cert (--cert-file, --key-file) must be provided for client url %s with HTTPS scheme", u.String())
+		}
+
+		network := "tcp"
+		addr := u.Host
+		if u.Scheme == "unix" || u.Scheme == "unixs" {
+			network = "unix"
+			addr = u.Host + u.Path
+		}
+		sctx.network = network
+
+		sctx.secure = u.Scheme == "https" || u.Scheme == "unixs"
+		sctx.insecure = !sctx.secure
+		if oldctx := sctxs[addr]; oldctx != nil {
+			oldctx.secure = oldctx.secure || sctx.secure
+			oldctx.insecure = oldctx.insecure || sctx.insecure
+			continue
+		}
+
+		if sctx.l, err = net.Listen(network, addr); err != nil {
+			return nil, err
+		}
+		// net.Listener will rewrite ipv4 0.0.0.0 to ipv6 [::], breaking
+		// hosts that disable ipv6. So, use the address given by the user.
+		sctx.addr = addr
+
+		if fdLimit, fderr := runtimeutil.FDLimit(); fderr == nil {
+			if fdLimit <= reservedInternalFDNum {
+				if cfg.logger != nil {
+					cfg.logger.Fatal(
+						"file descriptor limit of etcd process is too low; please set higher",
+						zap.Uint64("limit", fdLimit),
+						zap.Int("recommended-limit", reservedInternalFDNum),
+					)
+				} else {
+					plog.Fatalf("file descriptor limit[%d] of etcd process is too low, and should be set higher than %d to ensure internal usage", fdLimit, reservedInternalFDNum)
+				}
+			}
+			sctx.l = transport.LimitListener(sctx.l, int(fdLimit-reservedInternalFDNum))
+		}
+
+		if network == "tcp" {
+			if sctx.l, err = transport.NewKeepAliveListener(sctx.l, network, nil); err != nil {
+				return nil, err
+			}
+		}
+
+		defer func() {
+			if err == nil {
+				return
+			}
+			sctx.l.Close()
+			if cfg.logger != nil {
+				cfg.logger.Warn(
+					"closing peer listener",
+					zap.String("address", u.Host),
+					zap.Error(err),
+				)
+			} else {
+				plog.Info("stopping listening for client requests on ", u.Host)
+			}
+		}()
+		for k := range cfg.UserHandlers {
+			sctx.userHandlers[k] = cfg.UserHandlers[k]
+		}
+		sctx.serviceRegister = cfg.ServiceRegister
+		if cfg.EnablePprof || cfg.Debug {
+			sctx.registerPprof()
+		}
+		if cfg.Debug {
+			sctx.registerTrace()
+		}
+		sctxs[addr] = sctx
+	}
+	return sctxs, nil
+}
+
+func (e *Etcd) serveClients() (err error) {
+	if !e.cfg.ClientTLSInfo.Empty() {
+		if e.cfg.logger != nil {
+			e.cfg.logger.Info(
+				"starting with client TLS",
+				zap.String("tls-info", fmt.Sprintf("%+v", e.cfg.ClientTLSInfo)),
+				zap.Strings("cipher-suites", e.cfg.CipherSuites),
+			)
+		} else {
+			plog.Infof("ClientTLS: %s", e.cfg.ClientTLSInfo)
+		}
+	}
+
+	// Start a client server goroutine for each listen address
+	var h http.Handler
+	if e.Config().EnableV2 {
+		if len(e.Config().ExperimentalEnableV2V3) > 0 {
+			srv := v2v3.NewServer(e.cfg.logger, v3client.New(e.Server), e.cfg.ExperimentalEnableV2V3)
+			h = v2http.NewClientHandler(e.GetLogger(), srv, e.Server.Cfg.ReqTimeout())
+		} else {
+			h = v2http.NewClientHandler(e.GetLogger(), e.Server, e.Server.Cfg.ReqTimeout())
+		}
+	} else {
+		mux := http.NewServeMux()
+		etcdhttp.HandleBasic(mux, e.Server)
+		h = mux
+	}
+
+	gopts := []grpc.ServerOption{}
+	if e.cfg.GRPCKeepAliveMinTime > time.Duration(0) {
+		gopts = append(gopts, grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
+			MinTime:             e.cfg.GRPCKeepAliveMinTime,
+			PermitWithoutStream: false,
+		}))
+	}
+	if e.cfg.GRPCKeepAliveInterval > time.Duration(0) &&
+		e.cfg.GRPCKeepAliveTimeout > time.Duration(0) {
+		gopts = append(gopts, grpc.KeepaliveParams(keepalive.ServerParameters{
+			Time:    e.cfg.GRPCKeepAliveInterval,
+			Timeout: e.cfg.GRPCKeepAliveTimeout,
+		}))
+	}
+
+	// start client servers in each goroutine
+	for _, sctx := range e.sctxs {
+		go func(s *serveCtx) {
+			e.errHandler(s.serve(e.Server, &e.cfg.ClientTLSInfo, h, e.errHandler, gopts...))
+		}(sctx)
+	}
+	return nil
+}
+
+func (e *Etcd) serveMetrics() (err error) {
+	if e.cfg.Metrics == "extensive" {
+		grpc_prometheus.EnableHandlingTimeHistogram()
+	}
+
+	if len(e.cfg.ListenMetricsUrls) > 0 {
+		metricsMux := http.NewServeMux()
+		etcdhttp.HandleMetricsHealth(metricsMux, e.Server)
+
+		for _, murl := range e.cfg.ListenMetricsUrls {
+			tlsInfo := &e.cfg.ClientTLSInfo
+			if murl.Scheme == "http" {
+				tlsInfo = nil
+			}
+			ml, err := transport.NewListener(murl.Host, murl.Scheme, tlsInfo)
+			if err != nil {
+				return err
+			}
+			e.metricsListeners = append(e.metricsListeners, ml)
+			go func(u url.URL, ln net.Listener) {
+				if e.cfg.logger != nil {
+					e.cfg.logger.Info(
+						"serving metrics",
+						zap.String("address", u.String()),
+					)
+				} else {
+					plog.Info("listening for metrics on ", u.String())
+				}
+				e.errHandler(http.Serve(ln, metricsMux))
+			}(murl, ml)
+		}
+	}
+	return nil
+}
+
+func (e *Etcd) errHandler(err error) {
+	select {
+	case <-e.stopc:
+		return
+	default:
+	}
+	select {
+	case <-e.stopc:
+	case e.errc <- err:
+	}
+}
+
+// GetLogger returns the logger.
+func (e *Etcd) GetLogger() *zap.Logger {
+	e.cfg.loggerMu.RLock()
+	l := e.cfg.logger
+	e.cfg.loggerMu.RUnlock()
+	return l
+}
+
+func parseCompactionRetention(mode, retention string) (ret time.Duration, err error) {
+	h, err := strconv.Atoi(retention)
+	if err == nil {
+		switch mode {
+		case CompactorModeRevision:
+			ret = time.Duration(int64(h))
+		case CompactorModePeriodic:
+			ret = time.Duration(int64(h)) * time.Hour
+		}
+	} else {
+		// periodic compaction
+		ret, err = time.ParseDuration(retention)
+		if err != nil {
+			return 0, fmt.Errorf("error parsing CompactionRetention: %v", err)
+		}
+	}
+	return ret, nil
+}