diff --git a/vendor/github.com/coreos/etcd/proxy/grpcproxy/util.go b/vendor/github.com/coreos/etcd/proxy/grpcproxy/util.go
new file mode 100644
index 0000000..2b226fa
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/proxy/grpcproxy/util.go
@@ -0,0 +1,73 @@
+// Copyright 2017 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 grpcproxy
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+func getAuthTokenFromClient(ctx context.Context) string {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if ok {
+		ts, ok := md["token"]
+		if ok {
+			return ts[0]
+		}
+	}
+	return ""
+}
+
+func withClientAuthToken(ctx context.Context, ctxWithToken context.Context) context.Context {
+	token := getAuthTokenFromClient(ctxWithToken)
+	if token != "" {
+		ctx = context.WithValue(ctx, "token", token)
+	}
+	return ctx
+}
+
+type proxyTokenCredential struct {
+	token string
+}
+
+func (cred *proxyTokenCredential) RequireTransportSecurity() bool {
+	return false
+}
+
+func (cred *proxyTokenCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) {
+	return map[string]string{
+		"token": cred.token,
+	}, nil
+}
+
+func AuthUnaryClientInterceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
+	token := getAuthTokenFromClient(ctx)
+	if token != "" {
+		tokenCred := &proxyTokenCredential{token}
+		opts = append(opts, grpc.PerRPCCredentials(tokenCred))
+	}
+	return invoker(ctx, method, req, reply, cc, opts...)
+}
+
+func AuthStreamClientInterceptor(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
+	tokenif := ctx.Value("token")
+	if tokenif != nil {
+		tokenCred := &proxyTokenCredential{tokenif.(string)}
+		opts = append(opts, grpc.PerRPCCredentials(tokenCred))
+	}
+	return streamer(ctx, desc, cc, method, opts...)
+}