migrate leader election to lease API

Change-Id: I21fd5cdc1af59e456628cf15fc84b2d79db2eda0

Kubernetes-commit: 447295aff2bd8cdc92a2376553d83546a4d6eb41

tools/leaderelection/resourcelock/multilock.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2019 The Kubernetes 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 resourcelock
+
+import (
+	"bytes"
+	"encoding/json"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+)
+
+const (
+	UnknownLeader = "leaderelection.k8s.io/unknown"
+)
+
+// MultiLock is used for lock's migration
+type MultiLock struct {
+	Primary   Interface
+	Secondary Interface
+}
+
+// Get returns the older election record of the lock
+func (ml *MultiLock) Get() (*LeaderElectionRecord, []byte, error) {
+	primary, primaryRaw, err := ml.Primary.Get()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	secondary, secondaryRaw, err := ml.Secondary.Get()
+	if err != nil {
+		// Lock is held by old client
+		if apierrors.IsNotFound(err) && primary.HolderIdentity != ml.Identity() {
+			return primary, primaryRaw, nil
+		}
+		return nil, nil, err
+	}
+
+	if primary.HolderIdentity != secondary.HolderIdentity {
+		primary.HolderIdentity = UnknownLeader
+		primaryRaw, err = json.Marshal(primary)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	return primary, ConcatRawRecord(primaryRaw, secondaryRaw), nil
+}
+
+// Create attempts to create both primary lock and secondary lock
+func (ml *MultiLock) Create(ler LeaderElectionRecord) error {
+	err := ml.Primary.Create(ler)
+	if err != nil && !apierrors.IsAlreadyExists(err) {
+		return err
+	}
+	return ml.Secondary.Create(ler)
+}
+
+// Update will update and existing annotation on both two resources.
+func (ml *MultiLock) Update(ler LeaderElectionRecord) error {
+	err := ml.Primary.Update(ler)
+	if err != nil {
+		return err
+	}
+	_, _, err = ml.Secondary.Get()
+	if err != nil && apierrors.IsNotFound(err) {
+		return ml.Secondary.Create(ler)
+	}
+	return ml.Secondary.Update(ler)
+}
+
+// RecordEvent in leader election while adding meta-data
+func (ml *MultiLock) RecordEvent(s string) {
+	ml.Primary.RecordEvent(s)
+	ml.Secondary.RecordEvent(s)
+}
+
+// Describe is used to convert details on current resource lock
+// into a string
+func (ml *MultiLock) Describe() string {
+	return ml.Primary.Describe()
+}
+
+// Identity returns the Identity of the lock
+func (ml *MultiLock) Identity() string {
+	return ml.Primary.Identity()
+}
+
+func ConcatRawRecord(primaryRaw, secondaryRaw []byte) []byte {
+	return bytes.Join([][]byte{primaryRaw, secondaryRaw}, []byte(","))
+}