mirror of
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372 lines
14 KiB
Go
372 lines
14 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package podautoscaler
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import (
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"encoding/json"
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"fmt"
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"math"
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"time"
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"github.com/golang/glog"
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"k8s.io/kubernetes/pkg/api"
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"k8s.io/kubernetes/pkg/api/resource"
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"k8s.io/kubernetes/pkg/api/unversioned"
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"k8s.io/kubernetes/pkg/apis/extensions"
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"k8s.io/kubernetes/pkg/client/cache"
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"k8s.io/kubernetes/pkg/client/record"
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unversionedcore "k8s.io/kubernetes/pkg/client/typed/generated/core/unversioned"
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unversionedextensions "k8s.io/kubernetes/pkg/client/typed/generated/extensions/unversioned"
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"k8s.io/kubernetes/pkg/controller/framework"
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"k8s.io/kubernetes/pkg/controller/podautoscaler/metrics"
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"k8s.io/kubernetes/pkg/runtime"
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utilruntime "k8s.io/kubernetes/pkg/util/runtime"
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"k8s.io/kubernetes/pkg/watch"
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)
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const (
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// Usage shoud exceed the tolerance before we start downscale or upscale the pods.
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// TODO: make it a flag or HPA spec element.
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tolerance = 0.1
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defaultTargetCPUUtilizationPercentage = 80
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HpaCustomMetricsTargetAnnotationName = "alpha/target.custom-metrics.podautoscaler.kubernetes.io"
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HpaCustomMetricsStatusAnnotationName = "alpha/status.custom-metrics.podautoscaler.kubernetes.io"
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)
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type HorizontalController struct {
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scaleNamespacer unversionedextensions.ScalesGetter
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hpaNamespacer unversionedextensions.HorizontalPodAutoscalersGetter
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metricsClient metrics.MetricsClient
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eventRecorder record.EventRecorder
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// A store of HPA objects, populated by the controller.
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store cache.Store
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// Watches changes to all HPA objects.
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controller *framework.Controller
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}
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var downscaleForbiddenWindow = 5 * time.Minute
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var upscaleForbiddenWindow = 3 * time.Minute
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func NewHorizontalController(evtNamespacer unversionedcore.EventsGetter, scaleNamespacer unversionedextensions.ScalesGetter, hpaNamespacer unversionedextensions.HorizontalPodAutoscalersGetter, metricsClient metrics.MetricsClient, resyncPeriod time.Duration) *HorizontalController {
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broadcaster := record.NewBroadcaster()
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broadcaster.StartRecordingToSink(&unversionedcore.EventSinkImpl{evtNamespacer.Events("")})
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recorder := broadcaster.NewRecorder(api.EventSource{Component: "horizontal-pod-autoscaler"})
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controller := &HorizontalController{
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metricsClient: metricsClient,
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eventRecorder: recorder,
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scaleNamespacer: scaleNamespacer,
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hpaNamespacer: hpaNamespacer,
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}
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controller.store, controller.controller = framework.NewInformer(
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&cache.ListWatch{
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ListFunc: func(options api.ListOptions) (runtime.Object, error) {
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return controller.hpaNamespacer.HorizontalPodAutoscalers(api.NamespaceAll).List(options)
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},
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WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
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return controller.hpaNamespacer.HorizontalPodAutoscalers(api.NamespaceAll).Watch(options)
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},
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},
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&extensions.HorizontalPodAutoscaler{},
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resyncPeriod,
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framework.ResourceEventHandlerFuncs{
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AddFunc: func(obj interface{}) {
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hpa := obj.(*extensions.HorizontalPodAutoscaler)
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hasCPUPolicy := hpa.Spec.CPUUtilization != nil
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_, hasCustomMetricsPolicy := hpa.Annotations[HpaCustomMetricsTargetAnnotationName]
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if !hasCPUPolicy && !hasCustomMetricsPolicy {
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controller.eventRecorder.Event(hpa, api.EventTypeNormal, "DefaultPolicy", "No scaling policy specified - will use default one. See documentation for details")
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}
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err := controller.reconcileAutoscaler(hpa)
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if err != nil {
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glog.Warningf("Failed to reconcile %s: %v", hpa.Name, err)
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}
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},
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UpdateFunc: func(old, cur interface{}) {
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hpa := cur.(*extensions.HorizontalPodAutoscaler)
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err := controller.reconcileAutoscaler(hpa)
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if err != nil {
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glog.Warningf("Failed to reconcile %s: %v", hpa.Name, err)
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}
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},
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// We are not interested in deletions.
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},
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)
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return controller
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}
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func (a *HorizontalController) Run(stopCh <-chan struct{}) {
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defer utilruntime.HandleCrash()
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glog.Infof("Starting HPA Controller")
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go a.controller.Run(stopCh)
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<-stopCh
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glog.Infof("Shutting down HPA Controller")
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}
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func (a *HorizontalController) computeReplicasForCPUUtilization(hpa *extensions.HorizontalPodAutoscaler, scale *extensions.Scale) (int, *int, time.Time, error) {
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targetUtilization := defaultTargetCPUUtilizationPercentage
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if hpa.Spec.CPUUtilization != nil {
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targetUtilization = hpa.Spec.CPUUtilization.TargetPercentage
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}
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currentReplicas := scale.Status.Replicas
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currentUtilization, timestamp, err := a.metricsClient.GetCPUUtilization(hpa.Namespace, scale.Status.Selector)
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// TODO: what to do on partial errors (like metrics obtained for 75% of pods).
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if err != nil {
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a.eventRecorder.Event(hpa, api.EventTypeWarning, "FailedGetMetrics", err.Error())
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return 0, nil, time.Time{}, fmt.Errorf("failed to get CPU utilization: %v", err)
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}
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usageRatio := float64(*currentUtilization) / float64(targetUtilization)
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if math.Abs(1.0-usageRatio) > tolerance {
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return int(math.Ceil(usageRatio * float64(currentReplicas))), currentUtilization, timestamp, nil
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} else {
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return currentReplicas, currentUtilization, timestamp, nil
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}
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}
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// Computes the desired number of replicas based on the CustomMetrics passed in cmAnnotation as json-serialized
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// extensions.CustomMetricsTargetList.
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// Returns number of replicas, metric which required highest number of replicas,
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// status string (also json-serialized extensions.CustomMetricsCurrentStatusList),
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// last timestamp of the metrics involved in computations or error, if occurred.
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func (a *HorizontalController) computeReplicasForCustomMetrics(hpa *extensions.HorizontalPodAutoscaler, scale *extensions.Scale,
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cmAnnotation string) (replicas int, metric string, status string, timestamp time.Time, err error) {
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currentReplicas := scale.Status.Replicas
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replicas = 0
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metric = ""
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status = ""
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timestamp = time.Time{}
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err = nil
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if cmAnnotation == "" {
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return
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}
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var targetList extensions.CustomMetricTargetList
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if err := json.Unmarshal([]byte(cmAnnotation), &targetList); err != nil {
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return 0, "", "", time.Time{}, fmt.Errorf("failed to parse custom metrics annotation: %v", err)
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}
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if len(targetList.Items) == 0 {
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return 0, "", "", time.Time{}, fmt.Errorf("no custom metrics in annotation")
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}
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statusList := extensions.CustomMetricCurrentStatusList{
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Items: make([]extensions.CustomMetricCurrentStatus, 0),
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}
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for _, customMetricTarget := range targetList.Items {
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value, currentTimestamp, err := a.metricsClient.GetCustomMetric(customMetricTarget.Name, hpa.Namespace, scale.Status.Selector)
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// TODO: what to do on partial errors (like metrics obtained for 75% of pods).
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if err != nil {
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a.eventRecorder.Event(hpa, api.EventTypeWarning, "FailedGetCustomMetrics", err.Error())
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return 0, "", "", time.Time{}, fmt.Errorf("failed to get custom metric value: %v", err)
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}
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floatTarget := float64(customMetricTarget.TargetValue.MilliValue()) / 1000.0
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usageRatio := *value / floatTarget
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replicaCountProposal := 0
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if math.Abs(1.0-usageRatio) > tolerance {
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replicaCountProposal = int(math.Ceil(usageRatio * float64(currentReplicas)))
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} else {
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replicaCountProposal = currentReplicas
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}
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if replicaCountProposal > replicas {
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timestamp = currentTimestamp
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replicas = replicaCountProposal
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metric = fmt.Sprintf("Custom metric %s", customMetricTarget.Name)
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}
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quantity, err := resource.ParseQuantity(fmt.Sprintf("%.3f", *value))
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if err != nil {
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return 0, "", "", time.Time{}, fmt.Errorf("failed to set custom metric value: %v", err)
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}
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statusList.Items = append(statusList.Items, extensions.CustomMetricCurrentStatus{
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Name: customMetricTarget.Name,
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CurrentValue: *quantity,
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})
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}
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byteStatusList, err := json.Marshal(statusList)
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if err != nil {
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return 0, "", "", time.Time{}, fmt.Errorf("failed to serialize custom metric status: %v", err)
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}
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return replicas, metric, string(byteStatusList), timestamp, nil
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}
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func (a *HorizontalController) reconcileAutoscaler(hpa *extensions.HorizontalPodAutoscaler) error {
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reference := fmt.Sprintf("%s/%s/%s", hpa.Spec.ScaleRef.Kind, hpa.Namespace, hpa.Spec.ScaleRef.Name)
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scale, err := a.scaleNamespacer.Scales(hpa.Namespace).Get(hpa.Spec.ScaleRef.Kind, hpa.Spec.ScaleRef.Name)
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if err != nil {
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a.eventRecorder.Event(hpa, api.EventTypeWarning, "FailedGetScale", err.Error())
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return fmt.Errorf("failed to query scale subresource for %s: %v", reference, err)
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}
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currentReplicas := scale.Status.Replicas
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cpuDesiredReplicas := 0
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var cpuCurrentUtilization *int = nil
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cpuTimestamp := time.Time{}
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cmDesiredReplicas := 0
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cmMetric := ""
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cmStatus := ""
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cmTimestamp := time.Time{}
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desiredReplicas := 0
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rescaleReason := ""
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timestamp := time.Now()
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if currentReplicas > hpa.Spec.MaxReplicas {
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rescaleReason = "Current number of replicas above Spec.MaxReplicas"
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desiredReplicas = hpa.Spec.MaxReplicas
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} else if hpa.Spec.MinReplicas != nil && currentReplicas < *hpa.Spec.MinReplicas {
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rescaleReason = "Current number of replicas below Spec.MinReplicas"
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desiredReplicas = *hpa.Spec.MinReplicas
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} else if currentReplicas == 0 {
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rescaleReason = "Current number of replicas must be greater than 0"
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desiredReplicas = 1
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} else {
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// All basic scenarios covered, the state should be sane, lets use metrics.
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cmAnnotation, cmAnnotationFound := hpa.Annotations[HpaCustomMetricsTargetAnnotationName]
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if hpa.Spec.CPUUtilization != nil || !cmAnnotationFound {
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cpuDesiredReplicas, cpuCurrentUtilization, cpuTimestamp, err = a.computeReplicasForCPUUtilization(hpa, scale)
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if err != nil {
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a.updateCurrentReplicasInStatus(hpa, currentReplicas)
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a.eventRecorder.Event(hpa, api.EventTypeWarning, "FailedComputeReplicas", err.Error())
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return fmt.Errorf("failed to compute desired number of replicas based on CPU utilization for %s: %v", reference, err)
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}
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}
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if cmAnnotationFound {
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cmDesiredReplicas, cmMetric, cmStatus, cmTimestamp, err = a.computeReplicasForCustomMetrics(hpa, scale, cmAnnotation)
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if err != nil {
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a.updateCurrentReplicasInStatus(hpa, currentReplicas)
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a.eventRecorder.Event(hpa, api.EventTypeWarning, "FailedComputeCMReplicas", err.Error())
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return fmt.Errorf("failed to compute desired number of replicas based on Custom Metrics for %s: %v", reference, err)
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}
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}
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rescaleMetric := ""
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if cpuDesiredReplicas > desiredReplicas {
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desiredReplicas = cpuDesiredReplicas
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timestamp = cpuTimestamp
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rescaleMetric = "CPU utilization"
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}
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if cmDesiredReplicas > desiredReplicas {
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desiredReplicas = cmDesiredReplicas
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timestamp = cmTimestamp
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rescaleMetric = cmMetric
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}
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if desiredReplicas > currentReplicas {
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rescaleReason = fmt.Sprintf("%s above target", rescaleMetric)
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} else if desiredReplicas < currentReplicas {
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rescaleReason = "All metrics below target"
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}
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if hpa.Spec.MinReplicas != nil && desiredReplicas < *hpa.Spec.MinReplicas {
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desiredReplicas = *hpa.Spec.MinReplicas
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}
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// TODO: remove when pod idling is done.
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if desiredReplicas == 0 {
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desiredReplicas = 1
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}
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if desiredReplicas > hpa.Spec.MaxReplicas {
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desiredReplicas = hpa.Spec.MaxReplicas
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}
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}
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rescale := shouldScale(hpa, currentReplicas, desiredReplicas, timestamp)
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if rescale {
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scale.Spec.Replicas = desiredReplicas
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_, err = a.scaleNamespacer.Scales(hpa.Namespace).Update(hpa.Spec.ScaleRef.Kind, scale)
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if err != nil {
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a.eventRecorder.Eventf(hpa, api.EventTypeWarning, "FailedRescale", "New size: %d; reason: %s; error: %v", desiredReplicas, rescaleReason, err.Error())
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return fmt.Errorf("failed to rescale %s: %v", reference, err)
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}
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a.eventRecorder.Eventf(hpa, api.EventTypeNormal, "SuccessfulRescale", "New size: %d; reason: %s", desiredReplicas, rescaleReason)
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glog.Infof("Successfull rescale of %s, old size: %d, new size: %d, reason: %s",
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hpa.Name, currentReplicas, desiredReplicas, rescaleReason)
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} else {
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desiredReplicas = currentReplicas
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}
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return a.updateStatus(hpa, currentReplicas, desiredReplicas, cpuCurrentUtilization, cmStatus, rescale)
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}
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func shouldScale(hpa *extensions.HorizontalPodAutoscaler, currentReplicas, desiredReplicas int, timestamp time.Time) bool {
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if desiredReplicas != currentReplicas {
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// Going down only if the usageRatio dropped significantly below the target
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// and there was no rescaling in the last downscaleForbiddenWindow.
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if desiredReplicas < currentReplicas &&
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(hpa.Status.LastScaleTime == nil ||
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hpa.Status.LastScaleTime.Add(downscaleForbiddenWindow).Before(timestamp)) {
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return true
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}
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// Going up only if the usage ratio increased significantly above the target
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// and there was no rescaling in the last upscaleForbiddenWindow.
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if desiredReplicas > currentReplicas &&
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(hpa.Status.LastScaleTime == nil ||
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hpa.Status.LastScaleTime.Add(upscaleForbiddenWindow).Before(timestamp)) {
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return true
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}
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}
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return false
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}
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func (a *HorizontalController) updateCurrentReplicasInStatus(hpa *extensions.HorizontalPodAutoscaler, currentReplicas int) {
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err := a.updateStatus(hpa, currentReplicas, hpa.Status.DesiredReplicas, hpa.Status.CurrentCPUUtilizationPercentage, hpa.Annotations[HpaCustomMetricsStatusAnnotationName], false)
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if err != nil {
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glog.Errorf("%v", err)
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}
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}
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func (a *HorizontalController) updateStatus(hpa *extensions.HorizontalPodAutoscaler, currentReplicas, desiredReplicas int, cpuCurrentUtilization *int, cmStatus string, rescale bool) error {
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hpa.Status = extensions.HorizontalPodAutoscalerStatus{
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CurrentReplicas: currentReplicas,
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DesiredReplicas: desiredReplicas,
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CurrentCPUUtilizationPercentage: cpuCurrentUtilization,
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LastScaleTime: hpa.Status.LastScaleTime,
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}
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if cmStatus != "" {
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hpa.Annotations[HpaCustomMetricsStatusAnnotationName] = cmStatus
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}
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if rescale {
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now := unversioned.NewTime(time.Now())
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hpa.Status.LastScaleTime = &now
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}
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_, err := a.hpaNamespacer.HorizontalPodAutoscalers(hpa.Namespace).UpdateStatus(hpa)
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if err != nil {
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a.eventRecorder.Event(hpa, api.EventTypeWarning, "FailedUpdateStatus", err.Error())
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return fmt.Errorf("failed to update status for %s: %v", hpa.Name, err)
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}
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glog.V(2).Infof("Successfully updated status for %s", hpa.Name)
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return nil
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}
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