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CustomMetrics in HPA controller #20325

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merged 1 commit into from
Feb 2, 2016
Merged

CustomMetrics in HPA controller #20325

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114 changes: 109 additions & 5 deletions pkg/controller/podautoscaler/horizontal.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,12 +17,14 @@ limitations under the License.
package podautoscaler

import (
"encoding/json"
"fmt"
"math"
"time"

"github.com/golang/glog"
"k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/api/resource"
"k8s.io/kubernetes/pkg/api/unversioned"
"k8s.io/kubernetes/pkg/apis/extensions"
"k8s.io/kubernetes/pkg/client/record"
Expand All @@ -35,6 +37,9 @@ const (
// Usage shoud exceed the tolerance before we start downscale or upscale the pods.
// TODO: make it a flag or HPA spec element.
tolerance = 0.1

HpaCustomMetricsDefinitionAnnotationName = "alpha/definiton.custom-metrics.podautoscaler.kubernetes.io"
HpaCustomMetricsStatusAnnotationName = "alpha/status.custom-metrics.podautoscaler.kubernetes.io"
)

type HorizontalController struct {
Expand Down Expand Up @@ -93,6 +98,71 @@ func (a *HorizontalController) computeReplicasForCPUUtilization(hpa extensions.H
}
}

// Computes the desired number of replicas based on the CustomMetrics passed in cmAnnotation as json-serialized
// extensions.CustomMetricsTargetList.
// Returns number of replicas, status string (also json-serialized extensions.CustomMetricsCurrentStatusList),
// last timestamp of the metrics involved in computations or error, if occurred.
func (a *HorizontalController) computeReplicasForCustomMetrics(hpa extensions.HorizontalPodAutoscaler, scale *extensions.Scale,
cmAnnotation string) (int, string, time.Time, error) {

currentReplicas := scale.Status.Replicas
replicas := 0
timestamp := time.Time{}

if cmAnnotation == "" {
return 0, "", time.Time{}, nil
}

var targetList extensions.CustomMetricTargetList
if err := json.Unmarshal([]byte(cmAnnotation), &targetList); err != nil {
return 0, "", time.Time{}, fmt.Errorf("failed to parse custom metrics annotation: %v", err)
}
if len(targetList.Items) == 0 {
return 0, "", time.Time{}, fmt.Errorf("no custom metrics in annotation")
}

statusList := extensions.CustomMetricCurrentStatusList{
Items: make([]extensions.CustomMetricCurrentStatus, 0),
}

for _, customMetricTarget := range targetList.Items {
value, currentTimestamp, err := a.metricsClient.GetCustomMetric(customMetricTarget.Name, hpa.Namespace, scale.Status.Selector)
// TODO: what to do on partial errors (like metrics obtained for 75% of pods).
if err != nil {
a.eventRecorder.Event(&hpa, api.EventTypeWarning, "FailedGetCustomMetrics", err.Error())
return 0, "", time.Time{}, fmt.Errorf("failed to get custom metric value: %v", err)
}
floatTarget := float64(customMetricTarget.TargetValue.MilliValue()) / 1000.0
usageRatio := *value / floatTarget

replicaCountProposal := 0
if math.Abs(1.0-usageRatio) > tolerance {
replicaCountProposal = int(math.Ceil(usageRatio * float64(currentReplicas)))
} else {
replicaCountProposal = currentReplicas
}
if replicaCountProposal > replicas {
timestamp = currentTimestamp
replicas = replicaCountProposal
}
quantity, err := resource.ParseQuantity(fmt.Sprintf("%.3f", *value))
if err != nil {
return 0, "", time.Time{}, fmt.Errorf("failed to set custom metric value: %v", err)
}
statusList.Items = append(statusList.Items, extensions.CustomMetricCurrentStatus{
Name: customMetricTarget.Name,
CurrentValue: *quantity,
})
}
byteStatusList, err := json.Marshal(statusList)
if err != nil {
return 0, "", time.Time{}, fmt.Errorf("failed to serialize custom metric status: %v", err)
}

return replicas, string(byteStatusList), timestamp, nil

}

func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodAutoscaler) error {
reference := fmt.Sprintf("%s/%s/%s", hpa.Spec.ScaleRef.Kind, hpa.Namespace, hpa.Spec.ScaleRef.Name)

Expand All @@ -103,10 +173,40 @@ func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodA
}
currentReplicas := scale.Status.Replicas

desiredReplicas, currentUtilization, timestamp, err := a.computeReplicasForCPUUtilization(hpa, scale)
if err != nil {
a.eventRecorder.Event(&hpa, api.EventTypeWarning, "FailedComputeReplicas", err.Error())
return fmt.Errorf("failed to compute desired number of replicas based on CPU utilization for %s: %v", reference, err)
cpuDesiredReplicas := 0
var cpuCurrentUtilization *int = nil
cpuTimestamp := time.Time{}

cmDesiredReplicas := 0
cmStatus := ""
cmTimestamp := time.Time{}

if hpa.Spec.CPUUtilization != nil {
cpuDesiredReplicas, cpuCurrentUtilization, cpuTimestamp, err = a.computeReplicasForCPUUtilization(hpa, scale)
if err != nil {
a.eventRecorder.Event(&hpa, api.EventTypeWarning, "FailedComputeReplicas", err.Error())
return fmt.Errorf("failed to compute desired number of replicas based on CPU utilization for %s: %v", reference, err)
}
}

if cmAnnotation, cmAnnotationFound := hpa.Annotations[HpaCustomMetricsDefinitionAnnotationName]; cmAnnotationFound {
cmDesiredReplicas, cmStatus, cmTimestamp, err = a.computeReplicasForCustomMetrics(hpa, scale, cmAnnotation)
if err != nil {
a.eventRecorder.Event(&hpa, api.EventTypeWarning, "FailedComputeCMReplicas", err.Error())
return fmt.Errorf("failed to compute desired number of replicas based on Custom Metrics for %s: %v", reference, err)
}
}

desiredReplicas := 0
timestamp := time.Time{}

if cpuDesiredReplicas > desiredReplicas {
desiredReplicas = cpuDesiredReplicas
timestamp = cpuTimestamp
}
if cmDesiredReplicas > desiredReplicas {
desiredReplicas = cmDesiredReplicas
timestamp = cmTimestamp
}

if hpa.Spec.MinReplicas != nil && desiredReplicas < *hpa.Spec.MinReplicas {
Expand Down Expand Up @@ -158,9 +258,13 @@ func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodA
hpa.Status = extensions.HorizontalPodAutoscalerStatus{
CurrentReplicas: currentReplicas,
DesiredReplicas: desiredReplicas,
CurrentCPUUtilizationPercentage: currentUtilization,
CurrentCPUUtilizationPercentage: cpuCurrentUtilization,
LastScaleTime: hpa.Status.LastScaleTime,
}
if cmStatus != "" {
hpa.Annotations[HpaCustomMetricsStatusAnnotationName] = cmStatus
}

if rescale {
now := unversioned.NewTime(time.Now())
hpa.Status.LastScaleTime = &now
Expand Down
63 changes: 63 additions & 0 deletions pkg/controller/podautoscaler/horizontal_test.go
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,7 @@ type testCase struct {
CPUTarget int
reportedLevels []uint64
reportedCPURequests []resource.Quantity
cmTarget *extensions.CustomMetricTargetList
scaleUpdated bool
eventCreated bool
verifyEvents bool
Expand Down Expand Up @@ -101,6 +102,14 @@ func (tc *testCase) prepareTestClient(t *testing.T) *testclient.Fake {
if tc.CPUTarget > 0.0 {
obj.Items[0].Spec.CPUUtilization = &extensions.CPUTargetUtilization{TargetPercentage: tc.CPUTarget}
}
if tc.cmTarget != nil {
b, err := json.Marshal(tc.cmTarget)
if err != nil {
t.Fatalf("Failed to marshal cm: %v", err)
}
obj.Items[0].Annotations = make(map[string]string)
obj.Items[0].Annotations[HpaCustomMetricsDefinitionAnnotationName] = string(b)
}
return true, obj, nil
})

Expand Down Expand Up @@ -229,6 +238,25 @@ func TestScaleUp(t *testing.T) {
tc.runTest(t)
}

func TestScaleUpCM(t *testing.T) {
tc := testCase{
minReplicas: 2,
maxReplicas: 6,
initialReplicas: 3,
desiredReplicas: 4,
CPUTarget: 0,
cmTarget: &extensions.CustomMetricTargetList{
Items: []extensions.CustomMetricTarget{{
Name: "qps",
TargetValue: resource.MustParse("15.0"),
}},
},
reportedLevels: []uint64{20, 10, 30},
reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
}
tc.runTest(t)
}

func TestScaleDown(t *testing.T) {
tc := testCase{
minReplicas: 2,
Expand All @@ -242,6 +270,24 @@ func TestScaleDown(t *testing.T) {
tc.runTest(t)
}

func TestScaleDownCM(t *testing.T) {
tc := testCase{
minReplicas: 2,
maxReplicas: 6,
initialReplicas: 5,
desiredReplicas: 3,
CPUTarget: 0,
cmTarget: &extensions.CustomMetricTargetList{
Items: []extensions.CustomMetricTarget{{
Name: "qps",
TargetValue: resource.MustParse("20"),
}}},
reportedLevels: []uint64{12, 12, 12, 12, 12},
reportedCPURequests: []resource.Quantity{resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0"), resource.MustParse("1.0")},
}
tc.runTest(t)
}

func TestTolerance(t *testing.T) {
tc := testCase{
minReplicas: 1,
Expand All @@ -255,6 +301,23 @@ func TestTolerance(t *testing.T) {
tc.runTest(t)
}

func TestToleranceCM(t *testing.T) {
tc := testCase{
minReplicas: 1,
maxReplicas: 5,
initialReplicas: 3,
desiredReplicas: 3,
cmTarget: &extensions.CustomMetricTargetList{
Items: []extensions.CustomMetricTarget{{
Name: "qps",
TargetValue: resource.MustParse("20"),
}}},
reportedLevels: []uint64{20, 21, 21},
reportedCPURequests: []resource.Quantity{resource.MustParse("0.9"), resource.MustParse("1.0"), resource.MustParse("1.1")},
}
tc.runTest(t)
}

func TestMinReplicas(t *testing.T) {
tc := testCase{
minReplicas: 2,
Expand Down