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cluster.go
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cluster.go
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/*
Copyright 2016 The Kubernetes Authors All rights reserved.
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 simulator
import (
"flag"
"fmt"
"math"
"math/rand"
"time"
kube_api "k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/api/resource"
kube_client "k8s.io/kubernetes/pkg/client/unversioned"
cmd "k8s.io/kubernetes/pkg/kubectl/cmd"
"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
"github.com/golang/glog"
)
var (
skipNodesWithSystemPods = flag.Bool("skip-nodes-with-system-pods", true,
"If true cluster autoscaler will never delete nodes with pods from kube-system (except for DeamonSet "+
"or mirror pods)")
skipNodesWithLocalStorage = flag.Bool("skip-nodes-with-local-storage", true,
"If true cluster autoscaler will never delete nodes with pods with local storage, e.g. EmptyDir or HostPath")
)
// FindNodesToRemove finds nodes that can be removed. Returns also an information about good
// rescheduling location for each of the pods.
func FindNodesToRemove(candidates []*kube_api.Node, allNodes []*kube_api.Node, pods []*kube_api.Pod,
client *kube_client.Client, predicateChecker *PredicateChecker, maxCount int,
fastCheck bool, oldHints map[string]string, usageTracker *UsageTracker,
timestamp time.Time) (nodesToRemove []*kube_api.Node, podReschedulingHints map[string]string, finalError error) {
nodeNameToNodeInfo := schedulercache.CreateNodeNameToInfoMap(pods)
for _, node := range allNodes {
if nodeInfo, found := nodeNameToNodeInfo[node.Name]; found {
nodeInfo.SetNode(node)
}
}
result := make([]*kube_api.Node, 0)
evaluationType := "Detailed evaluation"
if fastCheck {
evaluationType = "Fast evaluation"
}
newHints := make(map[string]string, len(oldHints))
candidateloop:
for _, node := range candidates {
glog.V(2).Infof("%s: %s for removal", evaluationType, node.Name)
var podsToRemove []*kube_api.Pod
var err error
if fastCheck {
if nodeInfo, found := nodeNameToNodeInfo[node.Name]; found {
podsToRemove, err = FastGetPodsToMove(nodeInfo, false, *skipNodesWithSystemPods, *skipNodesWithLocalStorage)
if err != nil {
glog.V(2).Infof("%s: node %s cannot be removed: %v", evaluationType, node.Name, err)
continue candidateloop
}
} else {
glog.V(2).Infof("%s: nodeInfo for %s not found", evaluationType, node.Name)
continue candidateloop
}
} else {
drainResult, _, _, err := cmd.GetPodsForDeletionOnNodeDrain(client, node.Name,
kube_api.Codecs.UniversalDecoder(), false, true)
if err != nil {
glog.V(2).Infof("%s: node %s cannot be removed: %v", evaluationType, node.Name, err)
continue candidateloop
}
podsToRemove = make([]*kube_api.Pod, 0, len(drainResult))
for i := range drainResult {
podsToRemove = append(podsToRemove, &drainResult[i])
}
}
findProblems := findPlaceFor(node.Name, podsToRemove, allNodes, nodeNameToNodeInfo, predicateChecker, oldHints, newHints,
usageTracker, timestamp)
if findProblems == nil {
result = append(result, node)
glog.V(2).Infof("%s: node %s may be removed", evaluationType, node.Name)
if len(result) >= maxCount {
break candidateloop
}
} else {
glog.V(2).Infof("%s: node %s is not suitable for removal %v", evaluationType, node.Name, err)
}
}
return result, newHints, nil
}
// CalculateUtilization calculates utilization of a node, defined as total amount of requested resources divided by capacity.
func CalculateUtilization(node *kube_api.Node, nodeInfo *schedulercache.NodeInfo) (float64, error) {
cpu, err := calculateUtilizationOfResource(node, nodeInfo, kube_api.ResourceCPU)
if err != nil {
return 0, err
}
mem, err := calculateUtilizationOfResource(node, nodeInfo, kube_api.ResourceMemory)
if err != nil {
return 0, err
}
return math.Max(cpu, mem), nil
}
func calculateUtilizationOfResource(node *kube_api.Node, nodeInfo *schedulercache.NodeInfo, resourceName kube_api.ResourceName) (float64, error) {
nodeCapacity, found := node.Status.Capacity[resourceName]
if !found {
return 0, fmt.Errorf("Failed to get %v from %s", resourceName, node.Name)
}
if nodeCapacity.MilliValue() == 0 {
return 0, fmt.Errorf("%v is 0 at %s", resourceName, node.Name)
}
podsRequest := resource.MustParse("0")
for _, pod := range nodeInfo.Pods() {
for _, container := range pod.Spec.Containers {
if resourceValue, found := container.Resources.Requests[resourceName]; found {
podsRequest.Add(resourceValue)
}
}
}
return float64(podsRequest.MilliValue()) / float64(nodeCapacity.MilliValue()), nil
}
// TODO: We don't need to pass list of nodes here as they are already available in nodeInfos.
func findPlaceFor(removedNode string, pods []*kube_api.Pod, nodes []*kube_api.Node, nodeInfos map[string]*schedulercache.NodeInfo,
predicateChecker *PredicateChecker, oldHints map[string]string, newHints map[string]string, usageTracker *UsageTracker,
timestamp time.Time) error {
newNodeInfos := make(map[string]*schedulercache.NodeInfo)
podKey := func(pod *kube_api.Pod) string {
return fmt.Sprintf("%s/%s", pod.Namespace, pod.Name)
}
tryNodeForPod := func(nodename string, pod *kube_api.Pod) bool {
nodeInfo, found := newNodeInfos[nodename]
if !found {
nodeInfo, found = nodeInfos[nodename]
}
if found {
nodeInfo.Node().Status.Allocatable = nodeInfo.Node().Status.Capacity
err := predicateChecker.CheckPredicates(pod, nodeInfo)
glog.V(4).Infof("Evaluation %s for %s/%s -> %v", nodename, pod.Namespace, pod.Name, err)
if err == nil {
// TODO(mwielgus): Optimize it.
podsOnNode := nodeInfo.Pods()
podsOnNode = append(podsOnNode, pod)
newNodeInfo := schedulercache.NewNodeInfo(podsOnNode...)
newNodeInfo.SetNode(nodeInfo.Node())
newNodeInfos[nodename] = newNodeInfo
newHints[podKey(pod)] = nodename
return true
}
}
return false
}
// TODO: come up with a better semi-random semi-utilization sorted
// layout.
shuffledNodes := shuffleNodes(nodes)
for _, podptr := range pods {
newpod := *podptr
newpod.Spec.NodeName = ""
pod := &newpod
foundPlace := false
targetNode := ""
glog.V(4).Infof("Looking for place for %s/%s", pod.Namespace, pod.Name)
hintedNode, hasHint := oldHints[podKey(pod)]
if hasHint {
if hintedNode != removedNode && tryNodeForPod(hintedNode, pod) {
foundPlace = true
targetNode = hintedNode
}
}
if !foundPlace {
for _, node := range shuffledNodes {
if node.Name == removedNode {
continue
}
if tryNodeForPod(node.Name, pod) {
foundPlace = true
targetNode = node.Name
break
}
}
if !foundPlace {
return fmt.Errorf("failed to find place for %s", podKey)
}
}
usageTracker.RegisterUsage(removedNode, targetNode, timestamp)
}
return nil
}
func shuffleNodes(nodes []*kube_api.Node) []*kube_api.Node {
result := make([]*kube_api.Node, len(nodes))
for i := range nodes {
result[i] = nodes[i]
}
for i := range result {
j := rand.Intn(len(result))
result[i], result[j] = result[j], result[i]
}
return result
}