diff --git a/vendor/github.com/coreos/etcd/rafthttp/probing_status.go b/vendor/github.com/coreos/etcd/rafthttp/probing_status.go
new file mode 100644
index 0000000..109a0ae
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/rafthttp/probing_status.go
@@ -0,0 +1,76 @@
+// Copyright 2015 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 rafthttp
+
+import (
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/xiang90/probing"
+)
+
+var (
+	// proberInterval must be shorter than read timeout.
+	// Or the connection will time-out.
+	proberInterval           = ConnReadTimeout - time.Second
+	statusMonitoringInterval = 30 * time.Second
+	statusErrorInterval      = 5 * time.Second
+)
+
+const (
+	// RoundTripperNameRaftMessage is the name of round-tripper that sends
+	// all other Raft messages, other than "snap.Message".
+	RoundTripperNameRaftMessage = "ROUND_TRIPPER_RAFT_MESSAGE"
+	// RoundTripperNameSnapshot is the name of round-tripper that sends merged snapshot message.
+	RoundTripperNameSnapshot = "ROUND_TRIPPER_SNAPSHOT"
+)
+
+func addPeerToProber(p probing.Prober, id string, us []string, roundTripperName string, rttSecProm *prometheus.HistogramVec) {
+	hus := make([]string, len(us))
+	for i := range us {
+		hus[i] = us[i] + ProbingPrefix
+	}
+
+	p.AddHTTP(id, proberInterval, hus)
+
+	s, err := p.Status(id)
+	if err != nil {
+		plog.Errorf("failed to add peer %s into prober", id)
+	} else {
+		go monitorProbingStatus(s, id, roundTripperName, rttSecProm)
+	}
+}
+
+func monitorProbingStatus(s probing.Status, id string, roundTripperName string, rttSecProm *prometheus.HistogramVec) {
+	// set the first interval short to log error early.
+	interval := statusErrorInterval
+	for {
+		select {
+		case <-time.After(interval):
+			if !s.Health() {
+				plog.Warningf("health check for peer %s could not connect: %v (prober %q)", id, s.Err(), roundTripperName)
+				interval = statusErrorInterval
+			} else {
+				interval = statusMonitoringInterval
+			}
+			if s.ClockDiff() > time.Second {
+				plog.Warningf("the clock difference against peer %s is too high [%v > %v] (prober %q)", id, s.ClockDiff(), time.Second, roundTripperName)
+			}
+			rttSecProm.WithLabelValues(id).Observe(s.SRTT().Seconds())
+		case <-s.StopNotify():
+			return
+		}
+	}
+}