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topology_recovery.go
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topology_recovery.go
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/*
Copyright 2015 Shlomi Noach, courtesy Booking.com
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 logic
import (
"fmt"
goos "os"
"sort"
"strings"
"sync"
"time"
"github.com/github/orchestrator/go/attributes"
"github.com/github/orchestrator/go/config"
"github.com/github/orchestrator/go/inst"
"github.com/github/orchestrator/go/os"
"github.com/github/orchestrator/go/process"
"github.com/github/orchestrator/go/remote"
"github.com/openark/golib/log"
"github.com/patrickmn/go-cache"
"github.com/rcrowley/go-metrics"
)
// BlockedTopologyRecovery represents an entry in the blocked_topology_recovery table
type BlockedTopologyRecovery struct {
FailedInstanceKey inst.InstanceKey
ClusterName string
Analysis inst.AnalysisCode
LastBlockedTimestamp string
BlockingRecoveryId int64
}
// TopologyRecovery represents an entry in the topology_recovery table
type TopologyRecovery struct {
inst.PostponedFunctionsContainer
Id int64
AnalysisEntry inst.ReplicationAnalysis
SuccessorKey *inst.InstanceKey
SuccessorAlias string
IsActive bool
IsSuccessful bool
LostReplicas inst.InstanceKeyMap
ParticipatingInstanceKeys inst.InstanceKeyMap
AllErrors []string
RecoveryStartTimestamp string
RecoveryEndTimestamp string
ProcessingNodeHostname string
ProcessingNodeToken string
PostponedFunctions [](func() error)
Acknowledged bool
AcknowledgedAt string
AcknowledgedBy string
AcknowledgedComment string
LastDetectionId int64
RelatedRecoveryId int64
}
func NewTopologyRecovery(replicationAnalysis inst.ReplicationAnalysis) *TopologyRecovery {
topologyRecovery := &TopologyRecovery{}
topologyRecovery.AnalysisEntry = replicationAnalysis
topologyRecovery.SuccessorKey = nil
topologyRecovery.LostReplicas = *inst.NewInstanceKeyMap()
topologyRecovery.ParticipatingInstanceKeys = *inst.NewInstanceKeyMap()
topologyRecovery.AllErrors = []string{}
topologyRecovery.PostponedFunctions = [](func() error){}
return topologyRecovery
}
func (this *TopologyRecovery) AddError(err error) error {
if err != nil {
this.AllErrors = append(this.AllErrors, err.Error())
}
return err
}
func (this *TopologyRecovery) AddErrors(errs []error) {
for _, err := range errs {
this.AddError(err)
}
}
type MasterRecoveryType string
const (
MasterRecoveryGTID MasterRecoveryType = "MasterRecoveryGTID"
MasterRecoveryPseudoGTID = "MasterRecoveryPseudoGTID"
MasterRecoveryBinlogServer = "MasterRecoveryBinlogServer"
MasterRecoveryRemoteSSH = "MasterRecoveryRemoteSSH"
)
var emergencyReadTopologyInstanceMap = cache.New(time.Duration(config.Config.InstancePollSeconds)*time.Second, time.Second)
// InstancesByCountReplicas sorts instances by umber of replicas, descending
type InstancesByCountReplicas [](*inst.Instance)
func (this InstancesByCountReplicas) Len() int { return len(this) }
func (this InstancesByCountReplicas) Swap(i, j int) { this[i], this[j] = this[j], this[i] }
func (this InstancesByCountReplicas) Less(i, j int) bool {
if len(this[i].SlaveHosts) == len(this[j].SlaveHosts) {
// Secondary sorting: prefer more advanced replicas
return !this[i].ExecBinlogCoordinates.SmallerThan(&this[j].ExecBinlogCoordinates)
}
return len(this[i].SlaveHosts) < len(this[j].SlaveHosts)
}
var recoverDeadMasterCounter = metrics.NewCounter()
var recoverDeadMasterSuccessCounter = metrics.NewCounter()
var recoverDeadMasterFailureCounter = metrics.NewCounter()
var recoverDeadIntermediateMasterCounter = metrics.NewCounter()
var recoverDeadIntermediateMasterSuccessCounter = metrics.NewCounter()
var recoverDeadIntermediateMasterFailureCounter = metrics.NewCounter()
var recoverDeadCoMasterCounter = metrics.NewCounter()
var recoverDeadCoMasterSuccessCounter = metrics.NewCounter()
var recoverDeadCoMasterFailureCounter = metrics.NewCounter()
var recoverUnreachableMasterWithStaleSlavesCounter = metrics.NewCounter()
var recoverUnreachableMasterWithStaleSlavesSuccessCounter = metrics.NewCounter()
var recoverUnreachableMasterWithStaleSlavesFailureCounter = metrics.NewCounter()
func init() {
metrics.Register("recover.dead_master.start", recoverDeadMasterCounter)
metrics.Register("recover.dead_master.success", recoverDeadMasterSuccessCounter)
metrics.Register("recover.dead_master.fail", recoverDeadMasterFailureCounter)
metrics.Register("recover.dead_intermediate_master.start", recoverDeadIntermediateMasterCounter)
metrics.Register("recover.dead_intermediate_master.success", recoverDeadIntermediateMasterSuccessCounter)
metrics.Register("recover.dead_intermediate_master.fail", recoverDeadIntermediateMasterFailureCounter)
metrics.Register("recover.dead_co_master.start", recoverDeadCoMasterCounter)
metrics.Register("recover.dead_co_master.success", recoverDeadCoMasterSuccessCounter)
metrics.Register("recover.dead_co_master.fail", recoverDeadCoMasterFailureCounter)
metrics.Register("recover.unreach_master_stale_slaves.start", recoverUnreachableMasterWithStaleSlavesCounter)
metrics.Register("recover.unreach_master_stale_slaves.success", recoverUnreachableMasterWithStaleSlavesSuccessCounter)
metrics.Register("recover.unreach_master_stale_slaves.fail", recoverUnreachableMasterWithStaleSlavesFailureCounter)
}
// replaceCommandPlaceholders replaces agreed-upon placeholders with analysis data
func replaceCommandPlaceholders(command string, topologyRecovery *TopologyRecovery) string {
analysisEntry := &topologyRecovery.AnalysisEntry
command = strings.Replace(command, "{failureType}", string(analysisEntry.Analysis), -1)
command = strings.Replace(command, "{failureDescription}", analysisEntry.Description, -1)
command = strings.Replace(command, "{failedHost}", analysisEntry.AnalyzedInstanceKey.Hostname, -1)
command = strings.Replace(command, "{failedPort}", fmt.Sprintf("%d", analysisEntry.AnalyzedInstanceKey.Port), -1)
command = strings.Replace(command, "{failureCluster}", analysisEntry.ClusterDetails.ClusterName, -1)
command = strings.Replace(command, "{failureClusterAlias}", analysisEntry.ClusterDetails.ClusterAlias, -1)
command = strings.Replace(command, "{failureClusterDomain}", analysisEntry.ClusterDetails.ClusterDomain, -1)
command = strings.Replace(command, "{countSlaves}", fmt.Sprintf("%d", analysisEntry.CountReplicas), -1)
command = strings.Replace(command, "{countReplicas}", fmt.Sprintf("%d", analysisEntry.CountReplicas), -1)
command = strings.Replace(command, "{isDowntimed}", fmt.Sprint(analysisEntry.IsDowntimed), -1)
command = strings.Replace(command, "{autoMasterRecovery}", fmt.Sprint(analysisEntry.ClusterDetails.HasAutomatedMasterRecovery), -1)
command = strings.Replace(command, "{autoIntermediateMasterRecovery}", fmt.Sprint(analysisEntry.ClusterDetails.HasAutomatedIntermediateMasterRecovery), -1)
command = strings.Replace(command, "{orchestratorHost}", process.ThisHostname, -1)
command = strings.Replace(command, "{isSuccessful}", fmt.Sprint(topologyRecovery.SuccessorKey != nil), -1)
if topologyRecovery.SuccessorKey != nil {
command = strings.Replace(command, "{successorHost}", topologyRecovery.SuccessorKey.Hostname, -1)
command = strings.Replace(command, "{successorPort}", fmt.Sprintf("%d", topologyRecovery.SuccessorKey.Port), -1)
// As long as SucesssorKey != nil, we replace {successorAlias}.
// If SucessorAlias is "", it's fine. We'll replace {successorAlias} with "".
command = strings.Replace(command, "{successorAlias}", topologyRecovery.SuccessorAlias, -1)
}
command = strings.Replace(command, "{lostSlaves}", topologyRecovery.LostReplicas.ToCommaDelimitedList(), -1)
command = strings.Replace(command, "{lostReplicas}", topologyRecovery.LostReplicas.ToCommaDelimitedList(), -1)
command = strings.Replace(command, "{slaveHosts}", analysisEntry.SlaveHosts.ToCommaDelimitedList(), -1)
command = strings.Replace(command, "{replicaHosts}", analysisEntry.SlaveHosts.ToCommaDelimitedList(), -1)
return command
}
// replaceCommandPlaceholders replaces agreed-upon placeholders with analysis data
func applyEnvironmentVariables(topologyRecovery *TopologyRecovery) []string {
analysisEntry := &topologyRecovery.AnalysisEntry
env := goos.Environ()
env = append(env, fmt.Sprintf("ORC_FAILURE_TYPE=%s", string(analysisEntry.Analysis)))
env = append(env, fmt.Sprintf("ORC_FAILURE_DESCRIPTION=%s", analysisEntry.Description))
env = append(env, fmt.Sprintf("ORC_FAILED_HOST=%s", analysisEntry.AnalyzedInstanceKey.Hostname))
env = append(env, fmt.Sprintf("ORC_FAILED_PORT=%d", analysisEntry.AnalyzedInstanceKey.Port))
env = append(env, fmt.Sprintf("ORC_FAILURE_CLUSTER=%s", analysisEntry.ClusterDetails.ClusterName))
env = append(env, fmt.Sprintf("ORC_FAILURE_CLUSTER_ALIAS=%s", analysisEntry.ClusterDetails.ClusterAlias))
env = append(env, fmt.Sprintf("ORC_FAILURE_CLUSTER_DOMAIN=%s", analysisEntry.ClusterDetails.ClusterDomain))
env = append(env, fmt.Sprintf("ORC_COUNT_REPLICAS=%s", analysisEntry.CountReplicas))
env = append(env, fmt.Sprintf("ORC_IS_DOWNTIMED=%s", analysisEntry.IsDowntimed))
env = append(env, fmt.Sprintf("ORC_AUTO_MASTER_RECOVERY=%s", analysisEntry.ClusterDetails.HasAutomatedMasterRecovery))
env = append(env, fmt.Sprintf("ORC_AUTO_INTERMEDIATE_MASTER_RECOVERY=%s", analysisEntry.ClusterDetails.HasAutomatedIntermediateMasterRecovery))
env = append(env, fmt.Sprintf("ORC_ORCHESTRATOR_HOST=%s", process.ThisHostname))
env = append(env, fmt.Sprintf("ORC_IS_SUCCESSFUL=%s", (topologyRecovery.SuccessorKey != nil)))
env = append(env, fmt.Sprintf("ORC_LOST_REPLICAS=%s", topologyRecovery.LostReplicas.ToCommaDelimitedList()))
env = append(env, fmt.Sprintf("ORC_REPLICA_HOSTS=%s", analysisEntry.SlaveHosts.ToCommaDelimitedList()))
if topologyRecovery.SuccessorKey != nil {
env = append(env, fmt.Sprintf("ORC_SUCCESSOR_HOST=%s", topologyRecovery.SuccessorKey.Hostname))
env = append(env, fmt.Sprintf("ORC_SUCCESSOR_PORT=%d", topologyRecovery.SuccessorKey.Port))
// As long as SucesssorKey != nil, we replace {successorAlias}.
// If SucessorAlias is "", it's fine. We'll replace {successorAlias} with "".
env = append(env, fmt.Sprintf("ORC_SUCCESSOR_ALIAS=%s", topologyRecovery.SuccessorAlias))
}
return env
}
// executeProcesses executes a list of processes
func executeProcesses(processes []string, description string, topologyRecovery *TopologyRecovery, failOnError bool) error {
var err error
for _, command := range processes {
command := replaceCommandPlaceholders(command, topologyRecovery)
env := applyEnvironmentVariables(topologyRecovery)
if cmdErr := os.CommandRun(command, env); cmdErr == nil {
log.Infof("Executed %s command: %s", description, command)
} else {
if err == nil {
// Note first error
err = cmdErr
}
log.Errorf("Failed to execute %s command: %s", description, command)
if failOnError {
return err
}
}
}
return err
}
func recoverDeadMasterInBinlogServerTopology(topologyRecovery *TopologyRecovery) (promotedReplica *inst.Instance, err error) {
failedMasterKey := &topologyRecovery.AnalysisEntry.AnalyzedInstanceKey
var promotedBinlogServer *inst.Instance
_, promotedBinlogServer, err = inst.RegroupReplicasBinlogServers(failedMasterKey, true)
if err != nil {
return nil, log.Errore(err)
}
promotedBinlogServer, err = inst.StopSlave(&promotedBinlogServer.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
// Find candidate replica
promotedReplica, err = inst.GetCandidateReplicaOfBinlogServerTopology(&promotedBinlogServer.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
// Align it with binlog server coordinates
promotedReplica, err = inst.StopSlave(&promotedReplica.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
promotedReplica, err = inst.StartSlaveUntilMasterCoordinates(&promotedReplica.Key, &promotedBinlogServer.ExecBinlogCoordinates)
if err != nil {
return promotedReplica, log.Errore(err)
}
promotedReplica, err = inst.StopSlave(&promotedReplica.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
// Detach, flush binary logs forward
promotedReplica, err = inst.ResetSlave(&promotedReplica.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
promotedReplica, err = inst.FlushBinaryLogsTo(&promotedReplica.Key, promotedBinlogServer.ExecBinlogCoordinates.LogFile)
if err != nil {
return promotedReplica, log.Errore(err)
}
promotedReplica, err = inst.FlushBinaryLogs(&promotedReplica.Key, 1)
if err != nil {
return promotedReplica, log.Errore(err)
}
promotedReplica, err = inst.PurgeBinaryLogsToCurrent(&promotedReplica.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
// Reconnect binlog servers to promoted replica (now master):
promotedBinlogServer, err = inst.SkipToNextBinaryLog(&promotedBinlogServer.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
promotedBinlogServer, err = inst.Repoint(&promotedBinlogServer.Key, &promotedReplica.Key, inst.GTIDHintDeny)
if err != nil {
return nil, log.Errore(err)
}
func() {
// Move binlog server replicas up to replicate from master.
// This can only be done once a BLS has skipped to the next binlog
// We postpone this operation. The master is already promoted and we're happy.
binlogServerReplicas, err := inst.ReadBinlogServerReplicaInstances(&promotedBinlogServer.Key)
if err != nil {
return
}
maxBinlogServersToPromote := 3
for i, binlogServerReplica := range binlogServerReplicas {
binlogServerReplica := binlogServerReplica
if i >= maxBinlogServersToPromote {
return
}
postponedFunction := func() error {
binlogServerReplica, err := inst.StopSlave(&binlogServerReplica.Key)
if err != nil {
return err
}
// Make sure the BLS has the "next binlog" -- the one the master flushed & purged to. Otherwise the BLS
// will request a binlog the master does not have
if binlogServerReplica.ExecBinlogCoordinates.SmallerThan(&promotedBinlogServer.ExecBinlogCoordinates) {
binlogServerReplica, err = inst.StartSlaveUntilMasterCoordinates(&binlogServerReplica.Key, &promotedBinlogServer.ExecBinlogCoordinates)
if err != nil {
return err
}
}
_, err = inst.Repoint(&binlogServerReplica.Key, &promotedReplica.Key, inst.GTIDHintDeny)
return err
}
topologyRecovery.AddPostponedFunction(postponedFunction)
}
}()
return promotedReplica, err
}
func recoverDeadMasterViaRelaylogSync(topologyRecovery *TopologyRecovery) (promotedReplica *inst.Instance, syncedReplicas, failedReplicas, postponedReplicas [](*inst.Instance), err error) {
log.Debugf("recoverDeadMasterViaRelaylogSync")
failedMasterKey := &topologyRecovery.AnalysisEntry.AnalyzedInstanceKey
failedMaster, _, err := inst.ReadInstance(failedMasterKey)
if err != nil {
return promotedReplica, syncedReplicas, failedReplicas, postponedReplicas, err
}
var once sync.Once
var replacement *inst.Instance
var syncRelaylogsChangeMasterToFunc remote.SyncRelaylogsChangeMasterIdentityFunc = func(sourceReplica *inst.Instance, replicas ...*inst.Instance) (masterKey *inst.InstanceKey, coordinates *inst.BinlogCoordinates, err error) {
var replacementErr error
once.Do(func() {
log.Debugf("recoverDeadMasterViaRelaylogSync: getting best replacement for %+v from among its %+v replicas", failedMaster.Key, len(replicas))
replacement, replacementErr = GetBestMasterReplacementFromAmongItsReplicas(failedMaster, replicas, false)
log.Debugf("recoverDeadMasterViaRelaylogSync: + got nil? %+v ; error: %+v", (replacement == nil), replacementErr)
if replacementErr != nil {
return
}
replacement, replacementErr = inst.ReadTopologyInstance(&replacement.Key) // To get up-to-date SelfBinlogCoordinates
if replacementErr != nil {
return
}
log.Debugf("recoverDeadMasterViaRelaylogSync: master replacement is %+v", replacement.Key)
})
if replacementErr != nil {
return nil, nil, replacementErr
}
if replacement == nil {
return nil, nil, fmt.Errorf("recoverDeadMasterViaRelaylogSync: cannot find replacement")
}
return &replacement.Key, &replacement.SelfBinlogCoordinates, nil
}
syncFromReplica, syncedReplicas, failedReplicas, postponedReplicas, err := remote.SyncReplicasRelayLogs(failedMaster, syncRelaylogsChangeMasterToFunc, replacement, true, &topologyRecovery.PostponedFunctionsContainer)
log.Debugf("recoverDeadMasterViaRelaylogSync: syncFromReplica: %+v, synced: %d, failed: %d, postponed: %d", syncFromReplica.Key, len(syncedReplicas), len(failedReplicas), len(postponedReplicas))
if replacement != nil {
log.Debugf("recoverDeadMasterViaRelaylogSync: replacement: %+v", replacement.Key)
} else {
log.Debugf("recoverDeadMasterViaRelaylogSync: no replacement found")
}
promotedReplica = replacement
return promotedReplica, syncedReplicas, failedReplicas, postponedReplicas, err
}
func recoverDeadMasterViaRelaylogSyncCombined(topologyRecovery *TopologyRecovery) (promotedReplica *inst.Instance, syncedReplicas, failedReplicas, postponedReplicas [](*inst.Instance), err error) {
log.Debugf("recoverDeadMasterViaRelaylogSync")
failedMasterKey := &topologyRecovery.AnalysisEntry.AnalyzedInstanceKey
failedMaster, _, err := inst.ReadInstance(failedMasterKey)
if err != nil {
return promotedReplica, syncedReplicas, failedReplicas, postponedReplicas, err
}
log.Debugf("recoverDeadMasterViaRelaylogSync: checking who to promote to and copy relay logs to")
if _, promotedReplica, err = remote.SyncRelayLogsToSingleReplica(failedMaster, remote.SyncRelaylogsChangeMasterToTargetReplicaFunc, true); err != nil {
return promotedReplica, syncedReplicas, failedReplicas, postponedReplicas, err
}
if promotedReplica == nil {
return promotedReplica, syncedReplicas, failedReplicas, postponedReplicas, fmt.Errorf("recoverDeadMasterViaRelaylogSyncCombined: promotedReplica is nil")
}
log.Debugf("recoverDeadMasterViaRelaylogSync: relocating all replicas of %+v under %+v", failedMaster.Key, promotedReplica.Key)
relocatedReplicas, _, err, _ := inst.RelocateReplicas(&failedMaster.Key, &promotedReplica.Key, "")
return promotedReplica, relocatedReplicas, failedReplicas, postponedReplicas, err
}
// RecoverDeadMaster recovers a dead master, complete logic inside
func RecoverDeadMaster(topologyRecovery *TopologyRecovery, skipProcesses bool) (promotedReplica *inst.Instance, lostReplicas [](*inst.Instance), err error) {
analysisEntry := &topologyRecovery.AnalysisEntry
failedInstanceKey := &analysisEntry.AnalyzedInstanceKey
var cannotReplicateReplicas [](*inst.Instance)
inst.AuditOperation("recover-dead-master", failedInstanceKey, "problem found; will recover")
if !skipProcesses {
if err := executeProcesses(config.Config.PreFailoverProcesses, "PreFailoverProcesses", topologyRecovery, true); err != nil {
return nil, lostReplicas, topologyRecovery.AddError(err)
}
}
log.Debugf("topology_recovery: RecoverDeadMaster: will recover %+v", *failedInstanceKey)
var masterRecoveryType MasterRecoveryType = MasterRecoveryPseudoGTID
if analysisEntry.OracleGTIDImmediateTopology || analysisEntry.MariaDBGTIDImmediateTopology {
masterRecoveryType = MasterRecoveryGTID
} else if analysisEntry.BinlogServerImmediateTopology {
masterRecoveryType = MasterRecoveryBinlogServer
} else if config.Config.RemoteSSHForMasterFailover {
masterRecoveryType = MasterRecoveryRemoteSSH
}
log.Debugf("topology_recovery: RecoverDeadMaster: masterRecoveryType=%+v", masterRecoveryType)
switch masterRecoveryType {
case MasterRecoveryGTID:
{
lostReplicas, _, cannotReplicateReplicas, promotedReplica, err = inst.RegroupReplicasGTID(failedInstanceKey, true, nil)
}
case MasterRecoveryPseudoGTID:
{
lostReplicas, _, _, cannotReplicateReplicas, promotedReplica, err = inst.RegroupReplicasPseudoGTIDIncludingSubReplicasOfBinlogServers(failedInstanceKey, true, nil, &topologyRecovery.PostponedFunctionsContainer)
}
case MasterRecoveryBinlogServer:
{
promotedReplica, err = recoverDeadMasterInBinlogServerTopology(topologyRecovery)
}
case MasterRecoveryRemoteSSH:
{
promotedReplica, _, lostReplicas, _, err = recoverDeadMasterViaRelaylogSync(topologyRecovery)
//promotedReplica, _, lostReplicas, _, err = recoverDeadMasterViaRelaylogSyncCombined(topologyRecovery)
}
}
topologyRecovery.AddError(err)
lostReplicas = append(lostReplicas, cannotReplicateReplicas...)
if promotedReplica != nil && len(lostReplicas) > 0 && config.Config.DetachLostReplicasAfterMasterFailover {
postponedFunction := func() error {
log.Debugf("topology_recovery: - RecoverDeadMaster: lost %+v replicas during recovery process; detaching them", len(lostReplicas))
for _, replica := range lostReplicas {
replica := replica
inst.DetachReplicaOperation(&replica.Key)
}
return nil
}
topologyRecovery.AddPostponedFunction(postponedFunction)
}
if config.Config.MasterFailoverLostInstancesDowntimeMinutes > 0 {
postponedFunction := func() error {
inst.BeginDowntime(failedInstanceKey, inst.GetMaintenanceOwner(), inst.DowntimeLostInRecoveryMessage, config.Config.MasterFailoverLostInstancesDowntimeMinutes*60)
for _, replica := range lostReplicas {
replica := replica
inst.BeginDowntime(&replica.Key, inst.GetMaintenanceOwner(), inst.DowntimeLostInRecoveryMessage, config.Config.MasterFailoverLostInstancesDowntimeMinutes*60)
}
return nil
}
topologyRecovery.AddPostponedFunction(postponedFunction)
}
if promotedReplica == nil {
inst.AuditOperation("recover-dead-master", failedInstanceKey, "Failure: no replica promoted.")
} else {
inst.AuditOperation("recover-dead-master", failedInstanceKey, fmt.Sprintf("promoted replica: %+v", promotedReplica.Key))
}
return promotedReplica, lostReplicas, err
}
// replacePromotedReplicaWithCandidate is called after an intermediate master has died and been replaced by some promotedReplica.
// But, is there an even better replica to promote?
// if candidateInstanceKey is given, then it is forced to be promoted over the promotedReplica
// Otherwise, search for the best to promote!
func replacePromotedReplicaWithCandidate(deadInstanceKey *inst.InstanceKey, promotedReplica *inst.Instance, candidateInstanceKey *inst.InstanceKey) (*inst.Instance, error) {
candidateReplicas, _ := inst.ReadClusterCandidateInstances(promotedReplica.ClusterName)
// So we've already promoted a replica.
// However, can we improve on our choice? Are there any replicas marked with "is_candidate"?
// Maybe we actually promoted such a replica. Does that mean we should keep it?
// The current logic is:
// - 1. we prefer to promote a "is_candidate" which is in the same DC & env as the dead intermediate master (or do nothing if the promtoed replica is such one)
// - 2. we prefer to promote a "is_candidate" which is in the same DC & env as the promoted replica (or do nothing if the promtoed replica is such one)
// - 3. keep to current choice
log.Infof("topology_recovery: checking if should replace promoted replica with a better candidate")
if candidateInstanceKey == nil {
if deadInstance, _, err := inst.ReadInstance(deadInstanceKey); err == nil && deadInstance != nil {
for _, candidateReplica := range candidateReplicas {
if promotedReplica.Key.Equals(&candidateReplica.Key) &&
promotedReplica.DataCenter == deadInstance.DataCenter &&
promotedReplica.PhysicalEnvironment == deadInstance.PhysicalEnvironment {
// Seems like we promoted a candidate in the same DC & ENV as dead IM! Ideal! We're happy!
log.Infof("topology_recovery: promoted replica %+v is the ideal candidate", promotedReplica.Key)
return promotedReplica, nil
}
}
}
}
// We didn't pick the ideal candidate; let's see if we can replace with a candidate from same DC and ENV
if candidateInstanceKey == nil {
// Try a candidate replica that is in same DC & env as the dead instance
if deadInstance, _, err := inst.ReadInstance(deadInstanceKey); err == nil && deadInstance != nil {
for _, candidateReplica := range candidateReplicas {
if candidateReplica.DataCenter == deadInstance.DataCenter &&
candidateReplica.PhysicalEnvironment == deadInstance.PhysicalEnvironment &&
candidateReplica.MasterKey.Equals(&promotedReplica.Key) {
// This would make a great candidate
candidateInstanceKey = &candidateReplica.Key
log.Debugf("topology_recovery: no candidate was offered for %+v but orchestrator picks %+v as candidate replacement, based on being in same DC & env as failed instance", promotedReplica.Key, candidateReplica.Key)
}
}
}
}
if candidateInstanceKey == nil {
// We cannot find a candidate in same DC and ENV as dead master
for _, candidateReplica := range candidateReplicas {
if promotedReplica.Key.Equals(&candidateReplica.Key) {
// Seems like we promoted a candidate replica (though not in same DC and ENV as dead master). Good enough.
// No further action required.
log.Infof("topology_recovery: promoted replica %+v is a good candidate", promotedReplica.Key)
return promotedReplica, nil
}
}
}
// Still nothing?
if candidateInstanceKey == nil {
// Try a candidate replica that is in same DC & env as the promoted replica (our promoted replica is not an "is_candidate")
for _, candidateReplica := range candidateReplicas {
if promotedReplica.DataCenter == candidateReplica.DataCenter &&
promotedReplica.PhysicalEnvironment == candidateReplica.PhysicalEnvironment &&
candidateReplica.MasterKey.Equals(&promotedReplica.Key) {
// OK, better than nothing
candidateInstanceKey = &candidateReplica.Key
log.Debugf("topology_recovery: no candidate was offered for %+v but orchestrator picks %+v as candidate replacement, based on being in same DC & env as promoted instance", promotedReplica.Key, candidateReplica.Key)
}
}
}
// So do we have a candidate?
if candidateInstanceKey == nil {
// Found nothing. Stick with promoted replica
return promotedReplica, nil
}
if promotedReplica.Key.Equals(candidateInstanceKey) {
// Sanity. It IS the candidate, nothing to promote...
return promotedReplica, nil
}
// Try and promote suggested candidate, if applicable and possible
log.Debugf("topology_recovery: promoted instance %+v is not the suggested candidate %+v. Will see what can be done", promotedReplica.Key, *candidateInstanceKey)
candidateInstance, _, err := inst.ReadInstance(candidateInstanceKey)
if err != nil {
return promotedReplica, log.Errore(err)
}
if candidateInstance.MasterKey.Equals(&promotedReplica.Key) {
log.Debugf("topology_recovery: suggested candidate %+v is replica of promoted instance %+v. Will try and take its master", *candidateInstanceKey, promotedReplica.Key)
candidateInstance, err = inst.TakeMaster(&candidateInstance.Key)
if err != nil {
return promotedReplica, log.Errore(err)
}
log.Debugf("topology_recovery: success promoting %+v over %+v", *candidateInstanceKey, promotedReplica.Key)
return candidateInstance, nil
}
log.Debugf("topology_recovery: could not manage to promoted suggested candidate %+v", *candidateInstanceKey)
return promotedReplica, nil
}
// checkAndRecoverDeadMaster checks a given analysis, decides whether to take action, and possibly takes action
// Returns true when action was taken.
func checkAndRecoverDeadMaster(analysisEntry inst.ReplicationAnalysis, candidateInstanceKey *inst.InstanceKey, forceInstanceRecovery bool, skipProcesses bool) (bool, *TopologyRecovery, error) {
if !(forceInstanceRecovery || analysisEntry.ClusterDetails.HasAutomatedMasterRecovery) {
return false, nil, nil
}
topologyRecovery, err := AttemptRecoveryRegistration(&analysisEntry, !forceInstanceRecovery, !forceInstanceRecovery)
if topologyRecovery == nil {
log.Debugf("topology_recovery: found an active or recent recovery on %+v. Will not issue another RecoverDeadMaster.", analysisEntry.AnalyzedInstanceKey)
return false, nil, err
}
// That's it! We must do recovery!
log.Debugf("topology_recovery: will handle DeadMaster event on %+v", analysisEntry.ClusterDetails.ClusterName)
recoverDeadMasterCounter.Inc(1)
promotedReplica, lostReplicas, err := RecoverDeadMaster(topologyRecovery, skipProcesses)
topologyRecovery.LostReplicas.AddInstances(lostReplicas)
if promotedReplica != nil {
promotedReplica, err = replacePromotedReplicaWithCandidate(&analysisEntry.AnalyzedInstanceKey, promotedReplica, candidateInstanceKey)
topologyRecovery.AddError(err)
}
// And this is the end; whether successful or not, we're done.
ResolveRecovery(topologyRecovery, promotedReplica)
if promotedReplica != nil {
// Success!
recoverDeadMasterSuccessCounter.Inc(1)
if config.Config.ApplyMySQLPromotionAfterMasterFailover {
log.Debugf("topology_recovery: - RecoverDeadMaster: will apply MySQL changes to promoted master")
inst.ResetSlaveOperation(&promotedReplica.Key)
inst.SetReadOnly(&promotedReplica.Key, false)
}
if !skipProcesses {
// Execute post master-failover processes
executeProcesses(config.Config.PostMasterFailoverProcesses, "PostMasterFailoverProcesses", topologyRecovery, false)
}
if config.Config.MasterFailoverDetachReplicaMasterHost {
postponedFunction := func() error {
log.Debugf("topology_recovery: - RecoverDeadMaster: detaching master host on promoted master")
inst.DetachReplicaMasterHost(&promotedReplica.Key)
return nil
}
topologyRecovery.AddPostponedFunction(postponedFunction)
}
postponedFunction := func() error {
log.Debugf("topology_recovery: - RecoverDeadMaster: updating cluster_alias")
inst.ReplaceAliasClusterName(analysisEntry.AnalyzedInstanceKey.StringCode(), promotedReplica.Key.StringCode())
return nil
}
topologyRecovery.AddPostponedFunction(postponedFunction)
attributes.SetGeneralAttribute(analysisEntry.ClusterDetails.ClusterDomain, promotedReplica.Key.StringCode())
} else {
recoverDeadMasterFailureCounter.Inc(1)
}
return true, topologyRecovery, err
}
// isGeneralyValidAsCandidateSiblingOfIntermediateMaster sees that basic server configuration and state are valid
func isGeneralyValidAsCandidateSiblingOfIntermediateMaster(sibling *inst.Instance) bool {
if !sibling.LogBinEnabled {
return false
}
if !sibling.LogSlaveUpdatesEnabled {
return false
}
if !sibling.ReplicaRunning() {
return false
}
if !sibling.IsLastCheckValid {
return false
}
return true
}
// isValidAsCandidateSiblingOfIntermediateMaster checks to see that the given sibling is capable to take over instance's replicas
func isValidAsCandidateSiblingOfIntermediateMaster(intermediateMasterInstance *inst.Instance, sibling *inst.Instance) bool {
if sibling.Key.Equals(&intermediateMasterInstance.Key) {
// same instance
return false
}
if !isGeneralyValidAsCandidateSiblingOfIntermediateMaster(sibling) {
return false
}
if sibling.HasReplicationFilters != intermediateMasterInstance.HasReplicationFilters {
return false
}
if sibling.IsBinlogServer() != intermediateMasterInstance.IsBinlogServer() {
// When both are binlog servers, failover is trivial.
// When failed IM is binlog server, its sibling is still valid, but we catually prefer to just repoint the replica up -- simplest!
return false
}
if sibling.ExecBinlogCoordinates.SmallerThan(&intermediateMasterInstance.ExecBinlogCoordinates) {
return false
}
return true
}
func isGenerallyValidAsWouldBeMaster(replica *inst.Instance, requireLogSlaveUpdates bool) bool {
if !replica.IsLastCheckValid {
// something wrong with this replica right now. We shouldn't hope to be able to promote it
return false
}
if !replica.LogBinEnabled {
return false
}
if requireLogSlaveUpdates && !replica.LogSlaveUpdatesEnabled {
return false
}
if replica.IsBinlogServer() {
return false
}
if inst.IsBannedFromBeingCandidateReplica(replica) {
return false
}
return true
}
func GetBestMasterReplacementFromAmongItsReplicas(master *inst.Instance, replicas [](*inst.Instance), requireLogSlaveUpdates bool) (replacement *inst.Instance, err error) {
// Sanity:
for _, replica := range replicas {
if !replica.MasterKey.Equals(&master.Key) {
return nil, log.Errorf("GetBestMasterReplacementFromAmongItsReplicas: %+v is not a replica of %+v", replica.Key, master.Key)
}
}
validReplicas := [](*inst.Instance){}
for _, replica := range replicas {
if isGenerallyValidAsWouldBeMaster(replica, requireLogSlaveUpdates) {
validReplicas = append(validReplicas, replica)
}
}
for _, replica := range validReplicas {
if replica.IsCandidate &&
replica.DataCenter == master.DataCenter &&
replica.PhysicalEnvironment == master.PhysicalEnvironment {
log.Infof("GetBestMasterReplacementFromAmongItsReplicas: found %+v as the ideal candidate", replica.Key)
return replica, nil
}
}
for _, replica := range validReplicas {
if replica.IsCandidate &&
replica.DataCenter == master.DataCenter {
log.Infof("GetBestMasterReplacementFromAmongItsReplicas: found %+v as candidate in same dc", replica.Key)
return replica, nil
}
}
for _, replica := range validReplicas {
if replica.DataCenter == master.DataCenter &&
replica.PhysicalEnvironment == master.PhysicalEnvironment {
log.Infof("GetBestMasterReplacementFromAmongItsReplicas: found %+v as valid replacement in same dc & environment", replica.Key)
return replica, nil
}
}
for _, replica := range validReplicas {
if replica.DataCenter == master.DataCenter {
log.Infof("GetBestMasterReplacementFromAmongItsReplicas: found %+v as valid replacement in same dc", replica.Key)
return replica, nil
}
}
for _, replica := range validReplicas {
if replica.IsCandidate {
log.Infof("GetBestMasterReplacementFromAmongItsReplicas: found %+v as candidate in different dc", replica.Key)
return replica, nil
}
}
for _, replica := range validReplicas {
log.Infof("GetBestMasterReplacementFromAmongItsReplicas: found %+v as valid replacement in different dc", replica.Key)
return replica, nil
}
return nil, fmt.Errorf("GetBestMasterReplacementFromAmongItsReplicas: cannot find replacement")
}
// GetCandidateSiblingOfIntermediateMaster chooses the best sibling of a dead intermediate master
// to whom the IM's replicas can be moved.
func GetCandidateSiblingOfIntermediateMaster(intermediateMasterInstance *inst.Instance) (*inst.Instance, error) {
siblings, err := inst.ReadReplicaInstances(&intermediateMasterInstance.MasterKey)
if err != nil {
return nil, err
}
if len(siblings) <= 1 {
return nil, log.Errorf("topology_recovery: no siblings found for %+v", intermediateMasterInstance.Key)
}
sort.Sort(sort.Reverse(InstancesByCountReplicas(siblings)))
// In the next series of steps we attempt to return a good replacement.
// None of the below attempts is sure to pick a winning server. Perhaps picked server is not enough up-todate -- but
// this has small likelihood in the general case, and, well, it's an attempt. It's a Plan A, but we have Plan B & C if this fails.
// At first, we try to return an "is_candidate" server in same dc & env
log.Infof("topology_recovery: searching for the best candidate sibling of dead intermediate master")
for _, sibling := range siblings {
sibling := sibling
if isValidAsCandidateSiblingOfIntermediateMaster(intermediateMasterInstance, sibling) &&
sibling.IsCandidate &&
sibling.DataCenter == intermediateMasterInstance.DataCenter &&
sibling.PhysicalEnvironment == intermediateMasterInstance.PhysicalEnvironment {
log.Infof("topology_recovery: found %+v as the ideal candidate", sibling.Key)
return sibling, nil
}
}
// Go for something else in the same DC & ENV
for _, sibling := range siblings {
sibling := sibling
if isValidAsCandidateSiblingOfIntermediateMaster(intermediateMasterInstance, sibling) &&
sibling.DataCenter == intermediateMasterInstance.DataCenter &&
sibling.PhysicalEnvironment == intermediateMasterInstance.PhysicalEnvironment {
log.Infof("topology_recovery: found %+v as a replacement in same dc & environment", sibling.Key)
return sibling, nil
}
}
// Nothing in same DC & env, let's just go for some is_candidate
for _, sibling := range siblings {
sibling := sibling
if isValidAsCandidateSiblingOfIntermediateMaster(intermediateMasterInstance, sibling) && sibling.IsCandidate {
log.Infof("topology_recovery: found %+v as a good candidate", sibling.Key)
return sibling, nil
}
}
// Havent found an "is_candidate". Just whatever is valid.
for _, sibling := range siblings {
sibling := sibling
if isValidAsCandidateSiblingOfIntermediateMaster(intermediateMasterInstance, sibling) {
log.Infof("topology_recovery: found %+v as a replacement", sibling.Key)
return sibling, nil
}
}
return nil, log.Errorf("topology_recovery: cannot find candidate sibling of %+v", intermediateMasterInstance.Key)
}
// RecoverDeadIntermediateMaster performs intermediate master recovery; complete logic inside
func RecoverDeadIntermediateMaster(topologyRecovery *TopologyRecovery, skipProcesses bool) (successorInstance *inst.Instance, err error) {
analysisEntry := &topologyRecovery.AnalysisEntry
failedInstanceKey := &analysisEntry.AnalyzedInstanceKey
recoveryResolved := false
inst.AuditOperation("recover-dead-intermediate-master", failedInstanceKey, "problem found; will recover")
if !skipProcesses {
if err := executeProcesses(config.Config.PreFailoverProcesses, "PreFailoverProcesses", topologyRecovery, true); err != nil {
return nil, topologyRecovery.AddError(err)
}
}
intermediateMasterInstance, _, err := inst.ReadInstance(failedInstanceKey)
if err != nil {
return nil, topologyRecovery.AddError(err)
}
// Find possible candidate
candidateSiblingOfIntermediateMaster, err := GetCandidateSiblingOfIntermediateMaster(intermediateMasterInstance)
relocateReplicasToCandidateSibling := func() {
if candidateSiblingOfIntermediateMaster == nil {
return
}
// We have a candidate
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: will attempt a candidate intermediate master: %+v", candidateSiblingOfIntermediateMaster.Key)
relocatedReplicas, candidateSibling, err, errs := inst.RelocateReplicas(failedInstanceKey, &candidateSiblingOfIntermediateMaster.Key, "")
topologyRecovery.AddErrors(errs)
topologyRecovery.ParticipatingInstanceKeys.AddKey(candidateSiblingOfIntermediateMaster.Key)
if len(relocatedReplicas) == 0 {
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: failed to move any replica to candidate intermediate master (%+v)", candidateSibling.Key)
return
}
if err != nil || len(errs) > 0 {
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: move to candidate intermediate master (%+v) did not complete: %+v", candidateSibling.Key, err)
return
}
if err == nil {
recoveryResolved = true
successorInstance = candidateSibling
inst.AuditOperation("recover-dead-intermediate-master", failedInstanceKey, fmt.Sprintf("Relocated %d replicas under candidate sibling: %+v; %d errors: %+v", len(relocatedReplicas), candidateSibling.Key, len(errs), errs))
}
}
// Plan A: find a replacement intermediate master in same Data Center
if candidateSiblingOfIntermediateMaster != nil && candidateSiblingOfIntermediateMaster.DataCenter == intermediateMasterInstance.DataCenter {
relocateReplicasToCandidateSibling()
}
if !recoveryResolved {
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: will next attempt regrouping of replicas")
// Plan B: regroup (we wish to reduce cross-DC replication streams)
lostReplicas, _, _, _, regroupPromotedReplica, regroupError := inst.RegroupReplicas(failedInstanceKey, true, nil, nil)
if regroupError != nil {
topologyRecovery.AddError(regroupError)
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: regroup failed on: %+v", regroupError)
}
if regroupPromotedReplica != nil {
topologyRecovery.ParticipatingInstanceKeys.AddKey(regroupPromotedReplica.Key)
if len(lostReplicas) == 0 && regroupError == nil {
// Seems like the regroup worked flawlessly. The local replica took over all of its siblings.
// We can consider this host to be the successor.
successorInstance = regroupPromotedReplica
}
}
// Plan C: try replacement intermediate master in other DC...
if candidateSiblingOfIntermediateMaster != nil && candidateSiblingOfIntermediateMaster.DataCenter != intermediateMasterInstance.DataCenter {
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: will next attempt relocating to another DC server")
relocateReplicasToCandidateSibling()
}
}
if !recoveryResolved {
// Do we still have leftovers? some replicas couldn't move? Couldn't regroup? Only left with regroup's resulting leader?
// nothing moved?
// We don't care much if regroup made it or not. We prefer that it made it, in which case we only need to relocate up
// one replica, but the operation is still valid if regroup partially/completely failed. We just promote anything
// not regrouped.
// So, match up all that's left, plan D
log.Debugf("topology_recovery: - RecoverDeadIntermediateMaster: will next attempt to relocate up from %+v", *failedInstanceKey)
relocatedReplicas, masterInstance, err, errs := inst.RelocateReplicas(failedInstanceKey, &analysisEntry.AnalyzedInstanceMasterKey, "")
topologyRecovery.AddErrors(errs)
topologyRecovery.ParticipatingInstanceKeys.AddKey(analysisEntry.AnalyzedInstanceMasterKey)
if len(relocatedReplicas) > 0 {
recoveryResolved = true
if successorInstance == nil {
// There could have been a local replica taking over its siblings. We'd like to consider that one as successor.
successorInstance = masterInstance
}
inst.AuditOperation("recover-dead-intermediate-master", failedInstanceKey, fmt.Sprintf("Relocated replicas under: %+v %d errors: %+v", successorInstance.Key, len(errs), errs))
} else {
err = log.Errorf("topology_recovery: RecoverDeadIntermediateMaster failed to match up any replica from %+v", *failedInstanceKey)
topologyRecovery.AddError(err)
}
}
if !recoveryResolved {
successorInstance = nil
}
ResolveRecovery(topologyRecovery, successorInstance)
return successorInstance, err
}
// checkAndRecoverDeadIntermediateMaster checks a given analysis, decides whether to take action, and possibly takes action
// Returns true when action was taken.
func checkAndRecoverDeadIntermediateMaster(analysisEntry inst.ReplicationAnalysis, candidateInstanceKey *inst.InstanceKey, forceInstanceRecovery bool, skipProcesses bool) (bool, *TopologyRecovery, error) {
if !(forceInstanceRecovery || analysisEntry.ClusterDetails.HasAutomatedIntermediateMasterRecovery) {
return false, nil, nil
}
topologyRecovery, err := AttemptRecoveryRegistration(&analysisEntry, !forceInstanceRecovery, !forceInstanceRecovery)
if topologyRecovery == nil {
log.Debugf("topology_recovery: found an active or recent recovery on %+v. Will not issue another RecoverDeadIntermediateMaster.", analysisEntry.AnalyzedInstanceKey)
return false, nil, err
}
// That's it! We must do recovery!
recoverDeadIntermediateMasterCounter.Inc(1)
promotedReplica, err := RecoverDeadIntermediateMaster(topologyRecovery, skipProcesses)
if promotedReplica != nil {
// success
recoverDeadIntermediateMasterSuccessCounter.Inc(1)
if !skipProcesses {
// Execute post intermediate-master-failover processes
topologyRecovery.SuccessorKey = &promotedReplica.Key
topologyRecovery.SuccessorAlias = promotedReplica.InstanceAlias
executeProcesses(config.Config.PostIntermediateMasterFailoverProcesses, "PostIntermediateMasterFailoverProcesses", topologyRecovery, false)
}
} else {
recoverDeadIntermediateMasterFailureCounter.Inc(1)
}
return true, topologyRecovery, err
}
// RecoverDeadCoMaster recovers a dead co-master, complete logic inside
func RecoverDeadCoMaster(topologyRecovery *TopologyRecovery, skipProcesses bool) (promotedReplica *inst.Instance, lostReplicas [](*inst.Instance), err error) {
analysisEntry := &topologyRecovery.AnalysisEntry
failedInstanceKey := &analysisEntry.AnalyzedInstanceKey
otherCoMasterKey := &analysisEntry.AnalyzedInstanceMasterKey
otherCoMaster, found, _ := inst.ReadInstance(otherCoMasterKey)
if otherCoMaster == nil || !found {
return nil, lostReplicas, topologyRecovery.AddError(log.Errorf("RecoverDeadCoMaster: could not read info for co-master %+v of %+v", *otherCoMasterKey, *failedInstanceKey))
}
inst.AuditOperation("recover-dead-co-master", failedInstanceKey, "problem found; will recover")
if !skipProcesses {
if err := executeProcesses(config.Config.PreFailoverProcesses, "PreFailoverProcesses", topologyRecovery, true); err != nil {
return nil, lostReplicas, topologyRecovery.AddError(err)
}
}
log.Debugf("topology_recovery: RecoverDeadCoMaster: will recover %+v", *failedInstanceKey)
var coMasterRecoveryType MasterRecoveryType = MasterRecoveryPseudoGTID
if analysisEntry.OracleGTIDImmediateTopology || analysisEntry.MariaDBGTIDImmediateTopology {
coMasterRecoveryType = MasterRecoveryGTID
}
log.Debugf("topology_recovery: RecoverDeadCoMaster: coMasterRecoveryType=%+v", coMasterRecoveryType)
var cannotReplicateReplicas [](*inst.Instance)
switch coMasterRecoveryType {
case MasterRecoveryGTID:
{
lostReplicas, _, cannotReplicateReplicas, promotedReplica, err = inst.RegroupReplicasGTID(failedInstanceKey, true, nil)
}
case MasterRecoveryPseudoGTID:
{
lostReplicas, _, _, cannotReplicateReplicas, promotedReplica, err = inst.RegroupReplicasPseudoGTIDIncludingSubReplicasOfBinlogServers(failedInstanceKey, true, nil, &topologyRecovery.PostponedFunctionsContainer)
}
}
topologyRecovery.AddError(err)
lostReplicas = append(lostReplicas, cannotReplicateReplicas...)
mustPromoteOtherCoMaster := config.Config.CoMasterRecoveryMustPromoteOtherCoMaster
if !otherCoMaster.ReadOnly {
log.Debugf("topology_recovery: RecoverDeadCoMaster: other co-master %+v is writeable hence has to be promoted", otherCoMaster.Key)
mustPromoteOtherCoMaster = true
}
log.Debugf("topology_recovery: RecoverDeadCoMaster: mustPromoteOtherCoMaster? %+v", mustPromoteOtherCoMaster)
if promotedReplica != nil {
topologyRecovery.ParticipatingInstanceKeys.AddKey(promotedReplica.Key)
if mustPromoteOtherCoMaster {
log.Debugf("topology_recovery: mustPromoteOtherCoMaster. Verifying that %+v is/can be promoted", *otherCoMasterKey)
promotedReplica, err = replacePromotedReplicaWithCandidate(failedInstanceKey, promotedReplica, otherCoMasterKey)
} else {
// We are allowed to promote any server
promotedReplica, err = replacePromotedReplicaWithCandidate(failedInstanceKey, promotedReplica, nil)