sync code from copy destination

plugin/pkg/auth/authenticator/token/bootstrap/bootstrap.go

@@ -152,13 +152,12 @@ func (t *TokenAuthenticator) AuthenticateToken(token string) (user.Info, bool, e
 
 // Copied from k8s.io/client-go/tools/bootstrap/token/api
 func getSecretString(secret *api.Secret, key string) string {
-	if secret.Data == nil {
+	data, ok := secret.Data[key]
+	if !ok {
 		return ""
 	}
-	if val, ok := secret.Data[key]; ok {
-		return string(val)
-	}
-	return ""
+
+	return string(data)
 }
 
 // Copied from k8s.io/client-go/tools/bootstrap/token/api
@@ -167,11 +166,13 @@ func isSecretExpired(secret *api.Secret) bool {
 	if len(expiration) > 0 {
 		expTime, err2 := time.Parse(time.RFC3339, expiration)
 		if err2 != nil {
-			tokenErrorf(secret, "has unparsable expiration time (%s). Treating as expired.", expiration)
+			glog.V(3).Infof("Unparseable expiration time (%s) in %s/%s Secret: %v. Treating as expired.",
+				expiration, secret.Namespace, secret.Name, err2)
 			return true
 		}
 		if time.Now().After(expTime) {
-			tokenErrorf(secret, "has expired.", expiration)
+			glog.V(3).Infof("Expired bootstrap token in %s/%s Secret: %v",
+				secret.Namespace, secret.Name, expiration)
 			return true
 		}
 	}
@@ -181,8 +182,10 @@ func isSecretExpired(secret *api.Secret) bool {
 // Copied from kubernetes/cmd/kubeadm/app/util/token
 
 var (
+	// tokenRegexpString defines id.secret regular expression pattern
 	tokenRegexpString = "^([a-z0-9]{6})\\.([a-z0-9]{16})$"
-	tokenRegexp       = regexp.MustCompile(tokenRegexpString)
+	// tokenRegexp is a compiled regular expression of TokenRegexpString
+	tokenRegexp = regexp.MustCompile(tokenRegexpString)
 )
 
 // parseToken tries and parse a valid token from a string.