diff --git a/vendor/go.etcd.io/etcd/pkg/flags/strings.go b/vendor/go.etcd.io/etcd/pkg/flags/strings.go
new file mode 100644
index 0000000..3e47fb3
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/pkg/flags/strings.go
@@ -0,0 +1,52 @@
+// 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 flags
+
+import (
+	"flag"
+	"sort"
+	"strings"
+)
+
+// StringsValue wraps "sort.StringSlice".
+type StringsValue sort.StringSlice
+
+// Set parses a command line set of strings, separated by comma.
+// Implements "flag.Value" interface.
+func (ss *StringsValue) Set(s string) error {
+	*ss = strings.Split(s, ",")
+	return nil
+}
+
+// String implements "flag.Value" interface.
+func (ss *StringsValue) String() string { return strings.Join(*ss, ",") }
+
+// NewStringsValue implements string slice as "flag.Value" interface.
+// Given value is to be separated by comma.
+func NewStringsValue(s string) (ss *StringsValue) {
+	if s == "" {
+		return &StringsValue{}
+	}
+	ss = new(StringsValue)
+	if err := ss.Set(s); err != nil {
+		plog.Panicf("new StringsValue should never fail: %v", err)
+	}
+	return ss
+}
+
+// StringsFromFlag returns a string slice from the flag.
+func StringsFromFlag(fs *flag.FlagSet, flagName string) []string {
+	return []string(*fs.Lookup(flagName).Value.(*StringsValue))
+}