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GetExternalMetricReplicas ignores unready pods

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Similar to the change we made for `GetObjectMetricReplicas` in the
previous commit. Ensure that `GetExternalMetricReplicas` does not
include unready pods when its determining how many replica it desires.
Including unready pods can lead to over-scaling.

We did not change the behavior of `GetExternalPerPodMetricReplicas`, as
it is slightly less clear what is the desired behavior. We did make some
small naming refactorings to this method, which will make it easier to
ignore unready pods if we decide we want to.
This commit is contained in:
mattjmcnaughton 2018-03-07 08:57:11 -05:00
parent 7e3bce7b3e
commit d33494d459
3 changed files with 36 additions and 19 deletions
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2
pkg/controller/podautoscaler/horizontal.go
View File

@ -317,7 +317,7 @@ func (a *HorizontalController) computeReplicasForMetrics(hpa *autoscalingv2.Hori
},
}
} else if metricSpec.External.TargetValue != nil {
replicaCountProposal, utilizationProposal, timestampProposal, err = a.replicaCalc.GetExternalMetricReplicas(currentReplicas, metricSpec.External.TargetValue.MilliValue(), metricSpec.External.MetricName, hpa.Namespace, metricSpec.External.MetricSelector)
replicaCountProposal, utilizationProposal, timestampProposal, err = a.replicaCalc.GetExternalMetricReplicas(currentReplicas, metricSpec.External.TargetValue.MilliValue(), metricSpec.External.MetricName, hpa.Namespace, metricSpec.External.MetricSelector, selector)
if err != nil {
a.eventRecorder.Event(hpa, v1.EventTypeWarning, "FailedGetExternalMetric", err.Error())
setCondition(hpa, autoscalingv2.ScalingActive, v1.ConditionFalse, "FailedGetExternalMetric", "the HPA was unable to compute the replica count: %v", err)

33
pkg/controller/podautoscaler/replica_calculator.go
View File

@ -288,9 +288,6 @@ func (c *ReplicaCalculator) GetObjectMetricReplicas(currentReplicas int32, targe
return currentReplicas, utilization, timestamp, nil
}
// Calculate the total number of ready pods, as we want to base the
// replica count off of how many pods are ready, not how many pods
// exist.
readyPodCount, err := c.getReadyPodsCount(namespace, selector)
if err != nil {
@ -318,11 +315,9 @@ func (c *ReplicaCalculator) getReadyPodsCount(namespace string, selector labels.
readyPodCount := 0
for _, pod := range podList.Items {
if pod.Status.Phase != v1.PodRunning || !podutil.IsPodReady(&pod) {
continue
if pod.Status.Phase == v1.PodRunning && podutil.IsPodReady(&pod) {
readyPodCount++
}
readyPodCount++
}
return int64(readyPodCount), nil
@ -331,40 +326,46 @@ func (c *ReplicaCalculator) getReadyPodsCount(namespace string, selector labels.
// GetExternalMetricReplicas calculates the desired replica count based on a
// target metric value (as a milli-value) for the external metric in the given
// namespace, and the current replica count.
func (c *ReplicaCalculator) GetExternalMetricReplicas(currentReplicas int32, targetUtilization int64, metricName, namespace string, selector *metav1.LabelSelector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
labelSelector, err := metav1.LabelSelectorAsSelector(selector)
func (c *ReplicaCalculator) GetExternalMetricReplicas(currentReplicas int32, targetUtilization int64, metricName, namespace string, metricSelector *metav1.LabelSelector, podSelector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
metricLabelSelector, err := metav1.LabelSelectorAsSelector(metricSelector)
if err != nil {
return 0, 0, time.Time{}, err
}
metrics, timestamp, err := c.metricsClient.GetExternalMetric(metricName, namespace, labelSelector)
metrics, timestamp, err := c.metricsClient.GetExternalMetric(metricName, namespace, metricLabelSelector)
if err != nil {
return 0, 0, time.Time{}, fmt.Errorf("unable to get external metric %s/%s/%+v: %s", namespace, metricName, selector, err)
return 0, 0, time.Time{}, fmt.Errorf("unable to get external metric %s/%s/%+v: %s", namespace, metricName, metricSelector, err)
}
utilization = 0
for _, val := range metrics {
utilization = utilization + val
}
readyPodCount, err := c.getReadyPodsCount(namespace, podSelector)
if err != nil {
return 0, 0, time.Time{}, fmt.Errorf("unable to calculate ready pods: %s", err)
}
usageRatio := float64(utilization) / float64(targetUtilization)
if math.Abs(1.0-usageRatio) <= c.tolerance {
// return the current replicas if the change would be too small
return currentReplicas, utilization, timestamp, nil
}
return int32(math.Ceil(usageRatio * float64(currentReplicas))), utilization, timestamp, nil
return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, timestamp, nil
}
// GetExternalPerPodMetricReplicas calculates the desired replica count based on a
// target metric value per pod (as a milli-value) for the external metric in the
// given namespace, and the current replica count.
func (c *ReplicaCalculator) GetExternalPerPodMetricReplicas(currentReplicas int32, targetUtilizationPerPod int64, metricName, namespace string, selector *metav1.LabelSelector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
labelSelector, err := metav1.LabelSelectorAsSelector(selector)
func (c *ReplicaCalculator) GetExternalPerPodMetricReplicas(currentReplicas int32, targetUtilizationPerPod int64, metricName, namespace string, metricSelector *metav1.LabelSelector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
metricLabelSelector, err := metav1.LabelSelectorAsSelector(metricSelector)
if err != nil {
return 0, 0, time.Time{}, err
}
metrics, timestamp, err := c.metricsClient.GetExternalMetric(metricName, namespace, labelSelector)
metrics, timestamp, err := c.metricsClient.GetExternalMetric(metricName, namespace, metricLabelSelector)
if err != nil {
return 0, 0, time.Time{}, fmt.Errorf("unable to get external metric %s/%s/%+v: %s", namespace, metricName, selector, err)
return 0, 0, time.Time{}, fmt.Errorf("unable to get external metric %s/%s/%+v: %s", namespace, metricName, metricSelector, err)
}
utilization = 0
for _, val := range metrics {

20
pkg/controller/podautoscaler/replica_calculator_test.go
View File

@ -326,7 +326,7 @@ func (tc *replicaCalcTestCase) runTest(t *testing.T) {
outReplicas, outUtilization, outTimestamp, err = replicaCalc.GetObjectMetricReplicas(tc.currentReplicas, tc.metric.targetUtilization, tc.metric.name, testNamespace, tc.metric.singleObject, selector)
} else if tc.metric.selector != nil {
if tc.metric.targetUtilization > 0 {
outReplicas, outUtilization, outTimestamp, err = replicaCalc.GetExternalMetricReplicas(tc.currentReplicas, tc.metric.targetUtilization, tc.metric.name, testNamespace, tc.metric.selector)
outReplicas, outUtilization, outTimestamp, err = replicaCalc.GetExternalMetricReplicas(tc.currentReplicas, tc.metric.targetUtilization, tc.metric.name, testNamespace, tc.metric.selector, selector)
} else if tc.metric.perPodTargetUtilization > 0 {
outReplicas, outUtilization, outTimestamp, err = replicaCalc.GetExternalPerPodMetricReplicas(tc.currentReplicas, tc.metric.perPodTargetUtilization, tc.metric.name, testNamespace, tc.metric.selector)
}
@ -497,7 +497,7 @@ func TestReplicaCalcScaleUpCMObject(t *testing.T) {
tc.runTest(t)
}
func TestReplicaCalcScaleUpCMObjectIgnoreUnreadyPods(t *testing.T) {
func TestReplicaCalcScaleUpCMObjectIgnoresUnreadyPods(t *testing.T) {
tc := replicaCalcTestCase{
currentReplicas: 3,
expectedReplicas: 5, // If we did not ignore unready pods, we'd expect 15 replicas.
@ -532,6 +532,22 @@ func TestReplicaCalcScaleUpCMExternal(t *testing.T) {
tc.runTest(t)
}
func TestReplicaCalcScaleUpCMExternalIgnoresUnreadyPods(t *testing.T) {
tc := replicaCalcTestCase{
currentReplicas: 3,
expectedReplicas: 2, // Would expect 6 if we didn't ignore unready pods
podReadiness: []v1.ConditionStatus{v1.ConditionFalse, v1.ConditionTrue, v1.ConditionFalse},
metric: &metricInfo{
name: "qps",
levels: []int64{8600},
targetUtilization: 4400,
expectedUtilization: 8600,
selector: &metav1.LabelSelector{MatchLabels: map[string]string{"label": "value"}},
},
}
tc.runTest(t)
}
func TestReplicaCalcScaleUpCMExternalNoLabels(t *testing.T) {
tc := replicaCalcTestCase{
currentReplicas: 1,