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reconcile.go
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reconcile.go
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// Copyright 2016 The etcd-operator 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 cluster
import (
"errors"
"fmt"
"github.com/coreos/etcd-operator/pkg/spec"
"github.com/coreos/etcd-operator/pkg/util/constants"
"github.com/coreos/etcd-operator/pkg/util/etcdutil"
"github.com/coreos/etcd-operator/pkg/util/k8sutil"
"github.com/coreos/etcd/clientv3"
"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
"golang.org/x/net/context"
"k8s.io/api/core/v1"
)
// reconcile reconciles cluster current state to desired state specified by spec.
// - it tries to reconcile the cluster to desired size.
// - if the cluster needs for upgrade, it tries to upgrade old member one by one.
func (c *Cluster) reconcile(pods []*v1.Pod) error {
c.logger.Infoln("Start reconciling")
defer c.logger.Infoln("Finish reconciling")
defer func() {
c.status.Size = c.members.Size()
}()
sp := c.cluster.Spec
running := podsToMemberSet(pods, c.isSecureClient())
if !running.IsEqual(c.members) || c.members.Size() != sp.Size {
return c.reconcileMembers(running)
}
if needUpgrade(pods, sp) {
c.status.UpgradeVersionTo(sp.Version)
m := pickOneOldMember(pods, sp.Version)
return c.upgradeOneMember(m.Name)
}
c.status.SetVersion(sp.Version)
c.status.SetReadyCondition()
return nil
}
// reconcileMembers reconciles
// - running pods on k8s and cluster membership
// - cluster membership and expected size of etcd cluster
// Steps:
// 1. Remove all pods from running set that does not belong to member set.
// 2. L consist of remaining pods of runnings
// 3. If L = members, the current state matches the membership state. END.
// 4. If len(L) < len(members)/2 + 1, quorum lost. Go to recovery process.
// 5. Add one missing member. END.
func (c *Cluster) reconcileMembers(running etcdutil.MemberSet) error {
c.logger.Infof("running members: %s", running)
c.logger.Infof("cluster membership: %s", c.members)
unknownMembers := running.Diff(c.members)
if unknownMembers.Size() > 0 {
c.logger.Infof("removing unexpected pods: %v", unknownMembers)
for _, m := range unknownMembers {
if err := c.removePod(m.Name); err != nil {
return err
}
}
}
L := running.Diff(unknownMembers)
if L.Size() == c.members.Size() {
return c.resize()
}
if L.Size() < c.members.Size()/2+1 {
c.logger.Infof("Disaster recovery")
return c.disasterRecovery(L)
}
c.logger.Infof("removing one dead member")
// remove dead members that doesn't have any running pods before doing resizing.
return c.removeDeadMember(c.members.Diff(L).PickOne())
}
func (c *Cluster) resize() error {
if c.members.Size() == c.cluster.Spec.Size {
return nil
}
if c.members.Size() < c.cluster.Spec.Size {
if c.cluster.Spec.SelfHosted != nil {
return c.addOneSelfHostedMember()
}
return c.addOneMember()
}
return c.removeOneMember()
}
func (c *Cluster) addOneMember() error {
c.status.AppendScalingUpCondition(c.members.Size(), c.cluster.Spec.Size)
cfg := clientv3.Config{
Endpoints: c.members.ClientURLs(),
DialTimeout: constants.DefaultDialTimeout,
TLS: c.tlsConfig,
}
etcdcli, err := clientv3.New(cfg)
if err != nil {
return fmt.Errorf("add one member failed: creating etcd client failed %v", err)
}
defer etcdcli.Close()
newMember := c.newMember(c.memberCounter)
ctx, _ := context.WithTimeout(context.Background(), constants.DefaultRequestTimeout)
resp, err := etcdcli.MemberAdd(ctx, []string{newMember.PeerURL()})
if err != nil {
return fmt.Errorf("fail to add new member (%s): %v", newMember.Name, err)
}
newMember.ID = resp.Member.ID
c.members.Add(newMember)
if err := c.createPod(c.members, newMember, "existing", false); err != nil {
return fmt.Errorf("fail to create member's pod (%s): %v", newMember.Name, err)
}
c.memberCounter++
c.logger.Infof("added member (%s)", newMember.Name)
return nil
}
func (c *Cluster) removeOneMember() error {
c.status.AppendScalingDownCondition(c.members.Size(), c.cluster.Spec.Size)
return c.removeMember(c.members.PickOne())
}
func (c *Cluster) removeDeadMember(toRemove *etcdutil.Member) error {
if c.cluster.Spec.SelfHosted != nil {
selectedNodes, err := c.selectSchedulableNodes()
if err != nil {
return err
}
// If we do not have enough master nodes, we should simply wait for the old node
// to be online again.
//
// Removing the etcd member will not help us to recover the cluster to the desired
// number of members, since we do not have enough master nodes for self hosted etcd.
//
// Instead, there is a large chance that the old node is taken offline for maintenance
// or experiencing temporary network partition. When it comes back, it will recover itself
// since we persist data for self hosted case.
if nodeNum := len(selectedNodes); nodeNum < c.cluster.Spec.Size {
c.logger.Warningf("ignored removing failed member (%s). Not enough master nodes (%v) to recover, want at least %d", toRemove.Name, selectedNodes, c.cluster.Spec.Size)
c.logger.Infof("waiting for the failed master node to recover, or more master nodes")
return nil
}
}
c.logger.Infof("removing dead member %q", toRemove.Name)
c.status.AppendRemovingDeadMember(toRemove.Name)
return c.removeMember(toRemove)
}
func (c *Cluster) removeMember(toRemove *etcdutil.Member) error {
err := etcdutil.RemoveMember(c.members.ClientURLs(), c.tlsConfig, toRemove.ID)
if err != nil {
switch err {
case rpctypes.ErrMemberNotFound:
c.logger.Infof("etcd member (%v) has been removed", toRemove.Name)
default:
c.logger.Errorf("fail to remove etcd member (%v): %v", toRemove.Name, err)
return err
}
}
c.members.Remove(toRemove.Name)
if err := c.removePod(toRemove.Name); err != nil {
return err
}
c.logger.Infof("removed member (%v) with ID (%d)", toRemove.Name, toRemove.ID)
return nil
}
func (c *Cluster) disasterRecovery(left etcdutil.MemberSet) error {
c.status.AppendRecoveringCondition()
if c.cluster.Spec.SelfHosted != nil {
return errors.New("self-hosted cluster cannot be recovered from disaster")
}
if c.cluster.Spec.Backup == nil {
return newFatalError("fail to do disaster recovery: no backup policy has been defined")
}
backupNow := false
if len(left) > 0 {
c.logger.Infof("pods are still running (%v). Will try to make a latest backup from one of them.", left)
err := c.bm.requestBackup()
if err != nil {
c.logger.Errorln(err)
} else {
backupNow = true
}
}
if backupNow {
c.logger.Info("made a latest backup")
} else {
// We don't return error if backupnow failed. Instead, we ask if there is previous backup.
// If so, we can still continue. Otherwise, it's fatal error.
exist, err := c.bm.checkBackupExist(c.cluster.Spec.Version)
if err != nil {
c.logger.Errorln(err)
return err
}
if !exist {
return newFatalError("no backup exist for disaster recovery")
}
}
for _, m := range left {
err := c.removePod(m.Name)
if err != nil {
return err
}
}
return c.recover()
}
func needUpgrade(pods []*v1.Pod, cs spec.ClusterSpec) bool {
return len(pods) == cs.Size && pickOneOldMember(pods, cs.Version) != nil
}
func pickOneOldMember(pods []*v1.Pod, newVersion string) *etcdutil.Member {
for _, pod := range pods {
if k8sutil.GetEtcdVersion(pod) == newVersion {
continue
}
return &etcdutil.Member{Name: pod.Name, Namespace: pod.Namespace}
}
return nil
}