diff --git a/vendor/go.etcd.io/etcd/clientv3/client.go b/vendor/go.etcd.io/etcd/clientv3/client.go
index 445ecfe..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,
@@ -76,10 +81,9 @@
 	conn *grpc.ClientConn
 
 	cfg           Config
-	creds         *credentials.TransportCredentials
-	balancer      balancer.Balancer
+	creds         grpccredentials.TransportCredentials
 	resolverGroup *endpoint.ResolverGroup
-	mu            *sync.Mutex
+	mu            *sync.RWMutex
 
 	ctx    context.Context
 	cancel context.CancelFunc
@@ -87,9 +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
 
@@ -126,8 +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()
 	}
@@ -143,11 +150,13 @@
 func (c *Client) Ctx() context.Context { return c.ctx }
 
 // Endpoints lists the registered endpoints for the client.
-func (c *Client) Endpoints() (eps []string) {
+func (c *Client) Endpoints() []string {
 	// copy the slice; protect original endpoints from being changed
-	eps = make([]string, len(c.cfg.Endpoints))
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	eps := make([]string, len(c.cfg.Endpoints))
 	copy(eps, c.cfg.Endpoints)
-	return
+	return eps
 }
 
 // SetEndpoints updates client's endpoints.
@@ -192,24 +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":
@@ -219,9 +211,7 @@
 		if creds != nil {
 			break
 		}
-		tlsconfig := &tls.Config{}
-		emptyCreds := credentials.NewTLS(tlsconfig)
-		creds = &emptyCreds
+		creds = credentials.NewBundle(credentials.Config{}).TransportCredentials()
 	default:
 		creds = nil
 	}
@@ -229,7 +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,
@@ -254,7 +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())
 	}
@@ -288,8 +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)
@@ -317,10 +307,7 @@
 			continue
 		}
 
-		c.tokenCred.tokenMu.Lock()
-		c.tokenCred.token = resp.Token
-		c.tokenCred.tokenMu.Unlock()
-
+		c.authTokenBundle.UpdateAuthToken(resp.Token)
 		return nil
 	}
 
@@ -337,16 +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 {
@@ -363,7 +348,7 @@
 				return nil, err
 			}
 		} else {
-			opts = append(opts, grpc.WithPerRPCCredentials(c.tokenCred))
+			opts = append(opts, grpc.WithPerRPCCredentials(c.authTokenBundle.PerRPCCredentials()))
 		}
 		cancel()
 	}
@@ -384,26 +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 {
@@ -423,10 +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
@@ -442,7 +425,7 @@
 		creds:    creds,
 		ctx:      ctx,
 		cancel:   cancel,
-		mu:       new(sync.Mutex),
+		mu:       new(sync.RWMutex),
 		callOpts: defaultCallOpts,
 	}
 
@@ -540,13 +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()
@@ -558,8 +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
@@ -568,7 +562,7 @@
 		}(ep)
 	}
 	// wait for success
-	for i := 0; i < len(c.cfg.Endpoints); i++ {
+	for range eps {
 		if err = <-errc; err == nil {
 			break
 		}
@@ -608,10 +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 {
@@ -631,9 +628,6 @@
 			if ctx.Err() != nil {
 				err = ctx.Err()
 			}
-		case codes.Unavailable:
-		case codes.FailedPrecondition:
-			err = grpc.ErrClientConnClosing
 		}
 	}
 	return err
@@ -653,16 +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")
 }