diff --git a/vendor/go.etcd.io/etcd/raft/tracker/state.go b/vendor/go.etcd.io/etcd/raft/tracker/state.go
new file mode 100644
index 0000000..285b4b8
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/tracker/state.go
@@ -0,0 +1,42 @@
+// Copyright 2019 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 tracker
+
+// StateType is the state of a tracked follower.
+type StateType uint64
+
+const (
+	// StateProbe indicates a follower whose last index isn't known. Such a
+	// follower is "probed" (i.e. an append sent periodically) to narrow down
+	// its last index. In the ideal (and common) case, only one round of probing
+	// is necessary as the follower will react with a hint. Followers that are
+	// probed over extended periods of time are often offline.
+	StateProbe StateType = iota
+	// StateReplicate is the state steady in which a follower eagerly receives
+	// log entries to append to its log.
+	StateReplicate
+	// StateSnapshot indicates a follower that needs log entries not available
+	// from the leader's Raft log. Such a follower needs a full snapshot to
+	// return to StateReplicate.
+	StateSnapshot
+)
+
+var prstmap = [...]string{
+	"StateProbe",
+	"StateReplicate",
+	"StateSnapshot",
+}
+
+func (st StateType) String() string { return prstmap[uint64(st)] }