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cluster-placement.go
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cluster-placement.go
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package clustering
import (
"fmt"
"github.com/amadeusitgroup/redis-operator/pkg/redis"
"github.com/golang/glog"
)
const unknownVMName = "unknown" // <-- I hope nobody will ever name a VM "unknown" because this will impact the algorythm inside that package. Maybe you should generate a mangled name or amore complex name here to reduce probability.
// PlaceMasters used to select Redis Node knowing on which VM they are running in order to spread as possible
// the masters on different VMs.
// Improvement: Use Kube Node labeling instead of the "NodeName", (availability zone and so)
func PlaceMasters(cluster *redis.Cluster, currentMaster redis.Nodes, allPossibleMasters redis.Nodes, nbMaster int32) (redis.Nodes, bool, error) {
selection := redis.Nodes{}
selection = append(selection, currentMaster...)
// in case of scale down the current number of master is supperior to
// the number of needed master so we limit the size of the selection.
if len(selection) > int(nbMaster) {
selection = selection[0:nbMaster]
}
masterByVM := sortRedisNodeByVM(cluster, allPossibleMasters)
vmWithAlreadyMaster := sortRedisNodeByVM(cluster, currentMaster)
bestEffort := false
for len(selection) < int(nbMaster) {
isProgress := false
for vmName, nodes := range masterByVM {
if !bestEffort {
// discard vm with already Master(s) when we are not in best effort
if _, ok := vmWithAlreadyMaster[vmName]; ok {
continue
}
}
if len(nodes) == 0 {
continue
}
glog.Infof("- add node:%s to the master selection", nodes[0].ID)
selection = append(selection, nodes[0])
masterByVM[vmName] = nodes[1:]
isProgress = true
if len(selection) >= int(nbMaster) {
return selection, bestEffort, nil
}
}
if bestEffort && !isProgress {
glog.Errorf("Nothing appends since last loop, it means no more master available")
break
}
bestEffort = true
if glog.V(4) {
glog.Warning("the Pod are not spread enough on VMs to have only one Master by VM.")
}
}
glog.Infof("- bestEffort %v", bestEffort)
for _, node := range selection {
glog.Infof("- Master %s, ip:%s", node.ID, node.IP)
}
if len(selection) >= int(nbMaster) {
return selection, bestEffort, nil
}
return selection, bestEffort, fmt.Errorf("unable to found enough node for have the request number of master")
}
// PlaceSlaves used to select Redis Node knowing on which VM they are running in order to spread as possible
func PlaceSlaves(cluster *redis.Cluster, masters, oldSlaves, newSlaves redis.Nodes, replicationFactor int32) (map[string]redis.Nodes, bool) {
slavesByMaster := make(map[string]redis.Nodes)
// be sure that no oldSlaves is presentin in newSlaves
for _, newSlave := range newSlaves {
for _, oldSlaves := range oldSlaves {
if newSlave.ID == oldSlaves.ID {
removeIDFunc := func(node *redis.Node) bool {
return node.ID == newSlave.ID
}
newSlaves.FilterByFunc(removeIDFunc)
if glog.V(4) {
glog.Warning("Remove oldSlave for newSlave, id:", newSlave.ID)
}
}
}
}
newSlavesByVM := sortRedisNodeByVM(cluster, newSlaves)
for _, node := range masters {
slavesByMaster[node.ID] = redis.Nodes{}
}
for _, slave := range oldSlaves {
for _, master := range masters {
if slave.MasterReferent == master.ID {
if len(slavesByMaster[slave.MasterReferent]) >= int(replicationFactor) {
if node, err := cluster.GetNodeByID(slave.ID); err != nil {
vmName := unknownVMName
if node.Pod != nil && node.Pod.Spec.NodeName != "" {
vmName = node.Pod.Spec.NodeName
}
newSlavesByVM[vmName] = append(newSlavesByVM[vmName], slave)
}
} else {
//The master of this slave is among the new master nodes
slavesByMaster[slave.MasterReferent] = append(slavesByMaster[slave.MasterReferent], slave)
break
}
}
}
}
slavesByVMNotUsed := make(map[string]redis.Nodes)
isSlaveNodeUsed := false
// we iterate on free slaves by Vms
for vmName, slaves := range newSlavesByVM {
// then for this VM "vmName" we try to attach those slaves on a Master
for idPossibleSlave, possibleSlave := range slaves {
// Now we iterate on the Master and check if the current VM is already used for a Slave attach
// to the current master "idMaster"
slaveUsed := false
for idMaster, currentSlaves := range slavesByMaster {
if len(currentSlaves) >= int(replicationFactor) {
// already enough slaves attached to this master
continue
}
if checkIfSameVM(cluster, idMaster, vmName) {
continue
}
// lets check if the VM already host a slave for this master
vmAlreadyUsedForSlave := false
for _, currentSlave := range currentSlaves {
vmSlaveNode, err := cluster.GetNodeByID(currentSlave.ID)
if err != nil {
glog.Error("unable to find in the cluster the slave with id:", currentSlave.ID)
continue
}
vmSlaveName := unknownVMName
if vmSlaveNode.Pod != nil {
vmSlaveName = vmSlaveNode.Pod.Spec.NodeName
}
if vmName == vmSlaveName {
vmAlreadyUsedForSlave = true
break
}
}
if !vmAlreadyUsedForSlave {
// This vm is not already used for hosting a slave for this master so we can attach this slave to it.
slavesByMaster[idMaster] = append(slavesByMaster[idMaster], slaves[idPossibleSlave])
slaveUsed = true
break
}
}
if !slaveUsed {
isSlaveNodeUsed = true
// store unused slave for later dispatch
slavesByVMNotUsed[vmName] = append(slavesByVMNotUsed[vmName], possibleSlave)
}
}
}
bestEffort := false
if isSlaveNodeUsed {
bestEffort = true
if glog.V(4) {
glog.Warning("Unable to spread properly all the Slave on different VMs, we start best effort")
}
for _, freeSlaves := range slavesByVMNotUsed {
for _, freeSlave := range freeSlaves {
for masterID, slaves := range slavesByMaster {
if len(slaves) >= int(replicationFactor) {
continue
}
slavesByMaster[masterID] = append(slavesByMaster[masterID], freeSlave)
break
}
}
}
}
return slavesByMaster, bestEffort
}
func checkIfSameVM(cluster *redis.Cluster, redisID, vmName string) bool {
nodeVMName := unknownVMName
if vmNode, err := cluster.GetNodeByID(redisID); err == nil {
if vmNode.Pod != nil {
nodeVMName = vmNode.Pod.Spec.NodeName
}
}
if vmName == nodeVMName {
return true
}
return false
}
func sortRedisNodeByVM(cluster *redis.Cluster, nodes redis.Nodes) map[string]redis.Nodes {
nodesByVM := make(map[string]redis.Nodes)
for _, rnode := range nodes {
cnode, err := cluster.GetNodeByID(rnode.ID)
if err != nil {
glog.Errorf("[sortRedisNodeByVM] unable fo found the Cluster.Node with redis ID:%s", rnode.ID)
continue // if not then next line with cnode.Pod will cause a panic since cnode is nil
}
vmName := unknownVMName
if cnode.Pod != nil && cnode.Pod.Spec.NodeName != "" {
vmName = cnode.Pod.Spec.NodeName
}
if _, ok := nodesByVM[vmName]; !ok {
nodesByVM[vmName] = redis.Nodes{}
}
nodesByVM[vmName] = append(nodesByVM[vmName], rnode)
}
return nodesByVM
}