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selector_spreading.go
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/
selector_spreading.go
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/*
Copyright 2014 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 priorities
import (
"fmt"
"k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/kubernetes/pkg/scheduler/algorithm"
schedulerapi "k8s.io/kubernetes/pkg/scheduler/api"
schedulercache "k8s.io/kubernetes/pkg/scheduler/cache"
utilnode "k8s.io/kubernetes/pkg/util/node"
"github.com/golang/glog"
)
// When zone information is present, give 2/3 of the weighting to zone spreading, 1/3 to node spreading
// TODO: Any way to justify this weighting?
const zoneWeighting float64 = 2.0 / 3.0
// SelectorSpread contains information to calculate selector spread priority.
type SelectorSpread struct {
serviceLister algorithm.ServiceLister
controllerLister algorithm.ControllerLister
replicaSetLister algorithm.ReplicaSetLister
statefulSetLister algorithm.StatefulSetLister
}
// NewSelectorSpreadPriority creates a SelectorSpread.
func NewSelectorSpreadPriority(
serviceLister algorithm.ServiceLister,
controllerLister algorithm.ControllerLister,
replicaSetLister algorithm.ReplicaSetLister,
statefulSetLister algorithm.StatefulSetLister) (algorithm.PriorityMapFunction, algorithm.PriorityReduceFunction) {
selectorSpread := &SelectorSpread{
serviceLister: serviceLister,
controllerLister: controllerLister,
replicaSetLister: replicaSetLister,
statefulSetLister: statefulSetLister,
}
return selectorSpread.CalculateSpreadPriorityMap, selectorSpread.CalculateSpreadPriorityReduce
}
// CalculateSpreadPriorityMap spreads pods across hosts, considering pods
// belonging to the same service,RC,RS or StatefulSet.
// When a pod is scheduled, it looks for services, RCs,RSs and StatefulSets that match the pod,
// then finds existing pods that match those selectors.
// It favors nodes that have fewer existing matching pods.
// i.e. it pushes the scheduler towards a node where there's the smallest number of
// pods which match the same service, RC,RSs or StatefulSets selectors as the pod being scheduled.
func (s *SelectorSpread) CalculateSpreadPriorityMap(pod *v1.Pod, meta interface{}, nodeInfo *schedulercache.NodeInfo) (schedulerapi.HostPriority, error) {
var selectors []labels.Selector
node := nodeInfo.Node()
if node == nil {
return schedulerapi.HostPriority{}, fmt.Errorf("node not found")
}
priorityMeta, ok := meta.(*priorityMetadata)
if ok {
selectors = priorityMeta.podSelectors
} else {
selectors = getSelectors(pod, s.serviceLister, s.controllerLister, s.replicaSetLister, s.statefulSetLister)
}
if len(selectors) == 0 {
return schedulerapi.HostPriority{
Host: node.Name,
Score: int(0),
}, nil
}
count := int(0)
for _, nodePod := range nodeInfo.Pods() {
if pod.Namespace != nodePod.Namespace {
continue
}
// When we are replacing a failed pod, we often see the previous
// deleted version while scheduling the replacement.
// Ignore the previous deleted version for spreading purposes
// (it can still be considered for resource restrictions etc.)
if nodePod.DeletionTimestamp != nil {
glog.V(4).Infof("skipping pending-deleted pod: %s/%s", nodePod.Namespace, nodePod.Name)
continue
}
matches := false
for _, selector := range selectors {
if selector.Matches(labels.Set(nodePod.ObjectMeta.Labels)) {
matches = true
break
}
}
if matches {
count++
}
}
return schedulerapi.HostPriority{
Host: node.Name,
Score: int(count),
}, nil
}
// CalculateSpreadPriorityReduce calculates the source of each node
// based on the number of existing matching pods on the node
// where zone information is included on the nodes, it favors nodes
// in zones with fewer existing matching pods.
func (s *SelectorSpread) CalculateSpreadPriorityReduce(pod *v1.Pod, meta interface{}, nodeNameToInfo map[string]*schedulercache.NodeInfo, result schedulerapi.HostPriorityList) error {
countsByZone := make(map[string]int, 10)
maxCountByZone := int(0)
maxCountByNodeName := int(0)
for i := range result {
if result[i].Score > maxCountByNodeName {
maxCountByNodeName = result[i].Score
}
zoneID := utilnode.GetZoneKey(nodeNameToInfo[result[i].Host].Node())
if zoneID == "" {
continue
}
countsByZone[zoneID] += result[i].Score
}
for zoneID := range countsByZone {
if countsByZone[zoneID] > maxCountByZone {
maxCountByZone = countsByZone[zoneID]
}
}
haveZones := len(countsByZone) != 0
maxCountByNodeNameFloat64 := float64(maxCountByNodeName)
maxCountByZoneFloat64 := float64(maxCountByZone)
MaxPriorityFloat64 := float64(schedulerapi.MaxPriority)
for i := range result {
// initializing to the default/max node score of maxPriority
fScore := MaxPriorityFloat64
if maxCountByNodeName > 0 {
fScore = MaxPriorityFloat64 * (float64(maxCountByNodeName-result[i].Score) / maxCountByNodeNameFloat64)
}
// If there is zone information present, incorporate it
if haveZones {
zoneID := utilnode.GetZoneKey(nodeNameToInfo[result[i].Host].Node())
if zoneID != "" {
zoneScore := MaxPriorityFloat64
if maxCountByZone > 0 {
zoneScore = MaxPriorityFloat64 * (float64(maxCountByZone-countsByZone[zoneID]) / maxCountByZoneFloat64)
}
fScore = (fScore * (1.0 - zoneWeighting)) + (zoneWeighting * zoneScore)
}
}
result[i].Score = int(fScore)
if glog.V(10) {
glog.Infof(
"%v -> %v: SelectorSpreadPriority, Score: (%d)", pod.Name, result[i].Host, int(fScore),
)
}
}
return nil
}
// ServiceAntiAffinity contains information to calculate service anti-affinity priority.
type ServiceAntiAffinity struct {
podLister algorithm.PodLister
serviceLister algorithm.ServiceLister
label string
}
// NewServiceAntiAffinityPriority creates a ServiceAntiAffinity.
func NewServiceAntiAffinityPriority(podLister algorithm.PodLister, serviceLister algorithm.ServiceLister, label string) (algorithm.PriorityMapFunction, algorithm.PriorityReduceFunction) {
antiAffinity := &ServiceAntiAffinity{
podLister: podLister,
serviceLister: serviceLister,
label: label,
}
return antiAffinity.CalculateAntiAffinityPriorityMap, antiAffinity.CalculateAntiAffinityPriorityReduce
}
// Classifies nodes into ones with labels and without labels.
func (s *ServiceAntiAffinity) getNodeClassificationByLabels(nodes []*v1.Node) (map[string]string, []string) {
labeledNodes := map[string]string{}
nonLabeledNodes := []string{}
for _, node := range nodes {
if labels.Set(node.Labels).Has(s.label) {
label := labels.Set(node.Labels).Get(s.label)
labeledNodes[node.Name] = label
} else {
nonLabeledNodes = append(nonLabeledNodes, node.Name)
}
}
return labeledNodes, nonLabeledNodes
}
// filteredPod get pods based on namespace and selector
func filteredPod(namespace string, selector labels.Selector, nodeInfo *schedulercache.NodeInfo) (pods []*v1.Pod) {
if nodeInfo.Pods() == nil || len(nodeInfo.Pods()) == 0 || selector == nil {
return []*v1.Pod{}
}
for _, pod := range nodeInfo.Pods() {
// Ignore pods being deleted for spreading purposes
// Similar to how it is done for SelectorSpreadPriority
if namespace == pod.Namespace && pod.DeletionTimestamp == nil && selector.Matches(labels.Set(pod.Labels)) {
pods = append(pods, pod)
}
}
return
}
// CalculateAntiAffinityPriorityMap spreads pods by minimizing the number of pods belonging to the same service
// on given machine
func (s *ServiceAntiAffinity) CalculateAntiAffinityPriorityMap(pod *v1.Pod, meta interface{}, nodeInfo *schedulercache.NodeInfo) (schedulerapi.HostPriority, error) {
var firstServiceSelector labels.Selector
node := nodeInfo.Node()
if node == nil {
return schedulerapi.HostPriority{}, fmt.Errorf("node not found")
}
priorityMeta, ok := meta.(*priorityMetadata)
if ok {
firstServiceSelector = priorityMeta.podFirstServiceSelector
} else {
firstServiceSelector = getFirstServiceSelector(pod, s.serviceLister)
}
//pods matched namespace,selector on current node
matchedPodsOfNode := filteredPod(pod.Namespace, firstServiceSelector, nodeInfo)
return schedulerapi.HostPriority{
Host: node.Name,
Score: int(len(matchedPodsOfNode)),
}, nil
}
// CalculateAntiAffinityPriorityReduce computes each node score with the same value for a particular label.
// The label to be considered is provided to the struct (ServiceAntiAffinity).
func (s *ServiceAntiAffinity) CalculateAntiAffinityPriorityReduce(pod *v1.Pod, meta interface{}, nodeNameToInfo map[string]*schedulercache.NodeInfo, result schedulerapi.HostPriorityList) error {
var numServicePods int
var label string
podCounts := map[string]int{}
labelNodesStatus := map[string]string{}
maxPriorityFloat64 := float64(schedulerapi.MaxPriority)
for _, hostPriority := range result {
numServicePods += hostPriority.Score
if !labels.Set(nodeNameToInfo[hostPriority.Host].Node().Labels).Has(s.label) {
continue
}
label = labels.Set(nodeNameToInfo[hostPriority.Host].Node().Labels).Get(s.label)
labelNodesStatus[hostPriority.Host] = label
podCounts[label] += hostPriority.Score
}
//score int - scale of 0-maxPriority
// 0 being the lowest priority and maxPriority being the highest
for i, hostPriority := range result {
label, ok := labelNodesStatus[hostPriority.Host]
if !ok {
result[i].Host = hostPriority.Host
result[i].Score = int(0)
continue
}
// initializing to the default/max node score of maxPriority
fScore := maxPriorityFloat64
if numServicePods > 0 {
fScore = maxPriorityFloat64 * (float64(numServicePods-podCounts[label]) / float64(numServicePods))
}
result[i].Host = hostPriority.Host
result[i].Score = int(fScore)
}
return nil
}