Merge pull request #374 from zalando-incubator/configurable-buckets

Make the number of ramp steps configurable

README.md

@@ -720,12 +720,63 @@ The `ScalingSchedule` and `ClusterScalingSchedule` collectors allow
 collecting time-based metrics from the respective CRD objects specified
 in the HPA.
 
+These collectors are disabled by default, you have to start the server
+with the `--scaling-schedule` flag to enable it. Remember to deploy the CRDs
+`ScalingSchedule` and `ClusterScalingSchedule` and allow the service
+account used by the server to read, watch and list them.
+
 ### Supported metrics
 
 | Metric | Description | Type | K8s Versions |
 | ---------- | -------------- | ------- | -- |
 | ObjectName | The metric is calculated and stored for each `ScalingSchedule` and `ClusterScalingSchedule` referenced in the HPAs | `ScalingSchedule` and `ClusterScalingSchedule` | `>=1.16` |
 
+### Ramp-up and ramp-down feature
+
+To avoid abrupt scaling due to time based metrics,the `SchalingSchedule`
+collector has a feature of ramp-up and ramp-down the metric over a
+specific period of time. The duration of the scaling window can be
+configured individually in the `[Cluster]ScalingSchedule` object, via
+the option `scalingWindowDurationMinutes` or globally for all scheduled
+events, and defaults to a globally configured value if not specified.
+The default for the latter is set to 10 minutes, but can be changed
+using the `--scaling-schedule-default-scaling-window` flag.
+
+This spreads the scale events around, creating less load on the other
+components, and helping the rest of the metrics (like the CPU ones) to
+adjust as well.
+
+The [HPA algorithm][algo-details] does not make changes if the metric
+change is less than the specified by the
+`horizontal-pod-autoscaler-tolerance` flag:
+
+> We'll skip scaling if the ratio is sufficiently close to 1.0 (within a
+> globally-configurable tolerance, from the
+> `--horizontal-pod-autoscaler-tolerance` flag, which defaults to 0.1.
+
+With that in mind, the ramp-up and ramp-down feature divides the scaling
+over the specified period of time in buckets, trying to achieve changes
+bigger than the configured tolerance. The number of buckets defaults to
+10 and can be configured by the `--scaling-schedule-ramp-steps` flag.
+
+**Important**: note that the ramp-up and ramp-down feature can lead to
+deployments achieving less than the specified number of pods, due to the
+HPA 10% change rule and the ceiling function applied to the desired
+number of the pods (check the [algorithm details][algo-details]). It
+varies with the configured metric for `ScalingSchedule` events, the
+number of pods and the configured `horizontal-pod-autoscaler-tolerance`
+flag of your kubernetes installation. [This gist][gist] contains the code to
+simulate the situations a deployment with different number of pods, with
+a metric of 10000 can face with 10 buckets (max of 90% of the metric
+returned) and 5 buckets (max of 80% of the metric returned). The ramp-up
+and ramp-down feature can be disabled by setting
+`--scaling-schedule-default-scaling-window` to 0 and abrupt scalings can
+be handled via [scaling policies][policies].
+
+[algo-details]: https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/#algorithm-details
+[gist]: https://gist.github.com/jonathanbeber/37f1f918ab7ef6101c6ce56cc2cef3a2
+[policies]: https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/#scaling-policies
+
 ### Example
 
 This is an example of using the ScalingSchedule collectors to collect
@@ -826,8 +877,3 @@ Note that these number of pods are just considering these custom
 metrics, the normal HPA behavior still applies, such as: in case of
 multiple metrics the biggest number of pods is the utilized one, HPA max
 and min replica configuration, autoscaling policies, etc.
-
-These collectors are disabled by default, you have to start the server
-with the `--scaling-schedule` flag to enable it. Remember to deploy the CRDs
-`ScalingSchedule` and `ClusterScalingSchedule` and allow the service
-account used by the server to read, watch and list them.

docs/cluster_scaling_schedules_crd.yaml

@@ -37,6 +37,11 @@ spec:
           spec:
             description: ScalingScheduleSpec is the spec part of the ScalingSchedule.
             properties:
+              scalingWindowDurationMinutes:
+                description: Fade the scheduled values in and out over this many minutes.
+                  If unset, the default per-cluster value will be used.
+                format: int64
+                type: integer
               schedules:
                 description: Schedules is the list of schedules for this ScalingSchedule
                   resource. All the schedules defined here will result on the value
@@ -96,6 +101,7 @@ spec:
                     value:
                       description: The metric value that will be returned for the
                         defined schedule.
+                      format: int64
                       type: integer
                   required:
                   - durationMinutes

docs/scaling_schedules_crd.yaml

@@ -37,6 +37,11 @@ spec:
           spec:
             description: ScalingScheduleSpec is the spec part of the ScalingSchedule.
             properties:
+              scalingWindowDurationMinutes:
+                description: Fade the scheduled values in and out over this many minutes.
+                  If unset, the default per-cluster value will be used.
+                format: int64
+                type: integer
               schedules:
                 description: Schedules is the list of schedules for this ScalingSchedule
                   resource. All the schedules defined here will result on the value
@@ -96,6 +101,7 @@ spec:
                     value:
                       description: The metric value that will be returned for the
                         defined schedule.
+                      format: int64
                       type: integer
                   required:
                   - durationMinutes

pkg/apis/zalando.org/v1/types.go

@@ -1,6 +1,8 @@
 package v1
 
 import (
+	"time"
+
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
@@ -37,6 +39,10 @@ type ClusterScalingSchedule struct {
 // ScalingScheduleSpec is the spec part of the ScalingSchedule.
 // +k8s:deepcopy-gen=true
 type ScalingScheduleSpec struct {
+	// Fade the scheduled values in and out over this many minutes. If unset, the default per-cluster value will be used.
+	// +optional
+	ScalingWindowDurationMinutes *int64 `json:"scalingWindowDurationMinutes,omitempty"`
+
 	// Schedules is the list of schedules for this ScalingSchedule
 	// resource. All the schedules defined here will result on the value
 	// to the same metric. New metrics require a new ScalingSchedule
@@ -59,7 +65,11 @@ type Schedule struct {
 	// returned for the defined schedule.
 	DurationMinutes int `json:"durationMinutes"`
 	// The metric value that will be returned for the defined schedule.
-	Value int `json:"value"`
+	Value int64 `json:"value"`
+}
+
+func (in Schedule) Duration() time.Duration {
+	return time.Duration(in.DurationMinutes) * time.Minute
 }
 
 // Defines if the schedule is a OneTime schedule or

pkg/apis/zalando.org/v1/zz_generated.deepcopy.go

@@ -147,6 +147,11 @@ func (in *ScalingScheduleList) DeepCopyObject() runtime.Object {
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *ScalingScheduleSpec) DeepCopyInto(out *ScalingScheduleSpec) {
 	*out = *in
+	if in.ScalingWindowDurationMinutes != nil {
+		in, out := &in.ScalingWindowDurationMinutes, &out.ScalingWindowDurationMinutes
+		*out = new(int64)
+		**out = **in
+	}
 	if in.Schedules != nil {
 		in, out := &in.Schedules, &out.Schedules
 		*out = make([]Schedule, len(*in))

pkg/collector/httpmetrics/json_path.go

@@ -72,10 +72,25 @@ func (g *JSONPathMetricsGetter) GetMetric(metricsURL url.URL) (float64, error) {
 		return 0, err
 	}
 
-	if len(nodes) != 1 {
+	if len(nodes) == 0 {
 		return 0, fmt.Errorf("unexpected json: expected single numeric or array value")
 	}
 
+	if len(nodes) > 1 {
+		if g.aggregator == nil {
+			return 0, fmt.Errorf("no aggregator function has been specified")
+		}
+		values := make([]float64, 0, len(nodes))
+		for _, node := range nodes {
+			v, err := node.GetNumeric()
+			if err != nil {
+				return 0, fmt.Errorf("unexpected json: did not find numeric or array value '%s': %w", nodes, err)
+			}
+			values = append(values, v)
+		}
+		return g.aggregator(values...), nil
+	}
+
 	node := nodes[0]
 	if node.IsArray() {
 		if g.aggregator == nil {

pkg/collector/httpmetrics/json_path_test.go

@@ -51,6 +51,13 @@ func TestJSONPathMetricsGetter(t *testing.T) {
 			result:       5,
 			aggregator:   Average,
 		},
+		{
+			name:         "glob array query",
+			jsonResponse: []byte(`{"worker_status":[{"last_status":{"backlog":3}},{"last_status":{"backlog":7}}]}`),
+			jsonPath:     "$.worker_status.[*].last_status.backlog",
+			result:       5,
+			aggregator:   Average,
+		},
 		{
 			name:         "json path not resulting in array or number should lead to error",
 			jsonResponse: []byte(`{"metric.value":5}`),

pkg/collector/scaling_schedule_collector.go

@@ -3,6 +3,7 @@ package collector
 import (
 	"errors"
 	"fmt"
+	"math"
 	"time"
 
 	v1 "github.com/zalando-incubator/kube-metrics-adapter/pkg/apis/zalando.org/v1"
@@ -78,30 +79,38 @@ type Store interface {
 // ScalingScheduleCollectorPlugin is a collector plugin for initializing metrics
 // collectors for getting ScalingSchedule configured metrics.
 type ScalingScheduleCollectorPlugin struct {
-	store Store
-	now   Now
+	store                Store
+	now                  Now
+	defaultScalingWindow time.Duration
+	rampSteps            int
 }
 
 // ClusterScalingScheduleCollectorPlugin is a collector plugin for initializing metrics
 // collectors for getting ClusterScalingSchedule configured metrics.
 type ClusterScalingScheduleCollectorPlugin struct {
-	store Store
-	now   Now
+	store                Store
+	now                  Now
+	defaultScalingWindow time.Duration
+	rampSteps            int
 }
 
 // NewScalingScheduleCollectorPlugin initializes a new ScalingScheduleCollectorPlugin.
-func NewScalingScheduleCollectorPlugin(store Store, now Now) (*ScalingScheduleCollectorPlugin, error) {
+func NewScalingScheduleCollectorPlugin(store Store, now Now, defaultScalingWindow time.Duration, rampSteps int) (*ScalingScheduleCollectorPlugin, error) {
 	return &ScalingScheduleCollectorPlugin{
-		store: store,
-		now:   now,
+		store:                store,
+		now:                  now,
+		defaultScalingWindow: defaultScalingWindow,
+		rampSteps:            rampSteps,
 	}, nil
 }
 
 // NewClusterScalingScheduleCollectorPlugin initializes a new ClusterScalingScheduleCollectorPlugin.
-func NewClusterScalingScheduleCollectorPlugin(store Store, now Now) (*ClusterScalingScheduleCollectorPlugin, error) {
+func NewClusterScalingScheduleCollectorPlugin(store Store, now Now, defaultScalingWindow time.Duration, rampSteps int) (*ClusterScalingScheduleCollectorPlugin, error) {
 	return &ClusterScalingScheduleCollectorPlugin{
-		store: store,
-		now:   now,
+		store:                store,
+		now:                  now,
+		defaultScalingWindow: defaultScalingWindow,
+		rampSteps:            rampSteps,
 	}, nil
 }
 
@@ -109,14 +118,14 @@ func NewClusterScalingScheduleCollectorPlugin(store Store, now Now) (*ClusterSca
 // specified HPA. It's the only required method to implement the
 // collector.CollectorPlugin interface.
 func (c *ScalingScheduleCollectorPlugin) NewCollector(hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (Collector, error) {
-	return NewScalingScheduleCollector(c.store, c.now, hpa, config, interval)
+	return NewScalingScheduleCollector(c.store, c.defaultScalingWindow, c.rampSteps, c.now, hpa, config, interval)
 }
 
 // NewCollector initializes a new cluster wide scaling schedule
 // collector from the specified HPA. It's the only required method to
 // implement the collector.CollectorPlugin interface.
 func (c *ClusterScalingScheduleCollectorPlugin) NewCollector(hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (Collector, error) {
-	return NewClusterScalingScheduleCollector(c.store, c.now, hpa, config, interval)
+	return NewClusterScalingScheduleCollector(c.store, c.defaultScalingWindow, c.rampSteps, c.now, hpa, config, interval)
 }
 
 // ScalingScheduleCollector is a metrics collector for time based
@@ -135,41 +144,47 @@ type ClusterScalingScheduleCollector struct {
 // struct used by both ClusterScalingScheduleCollector and the
 // ScalingScheduleCollector.
 type scalingScheduleCollector struct {
-	store           Store
-	now             Now
-	metric          autoscalingv2.MetricIdentifier
-	objectReference custom_metrics.ObjectReference
-	hpa             *autoscalingv2.HorizontalPodAutoscaler
-	interval        time.Duration
-	config          MetricConfig
+	store                Store
+	now                  Now
+	metric               autoscalingv2.MetricIdentifier
+	objectReference      custom_metrics.ObjectReference
+	hpa                  *autoscalingv2.HorizontalPodAutoscaler
+	interval             time.Duration
+	config               MetricConfig
+	defaultScalingWindow time.Duration
+	rampSteps            int
 }
 
 // NewScalingScheduleCollector initializes a new ScalingScheduleCollector.
-func NewScalingScheduleCollector(store Store, now Now, hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (*ScalingScheduleCollector, error) {
+func NewScalingScheduleCollector(store Store, defaultScalingWindow time.Duration, rampSteps int, now Now, hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (*ScalingScheduleCollector, error) {
 	return &ScalingScheduleCollector{
 		scalingScheduleCollector{
-			store:           store,
-			now:             now,
-			objectReference: config.ObjectReference,
-			hpa:             hpa,
-			metric:          config.Metric,
-			interval:        interval,
-			config:          *config,
+			store:                store,
+			now:                  now,
+			objectReference:      config.ObjectReference,
+			hpa:                  hpa,
+			metric:               config.Metric,
+			interval:             interval,
+			config:               *config,
+			defaultScalingWindow: defaultScalingWindow,
+			rampSteps:            rampSteps,
 		},
 	}, nil
 }
 
 // NewClusterScalingScheduleCollector initializes a new ScalingScheduleCollector.
-func NewClusterScalingScheduleCollector(store Store, now Now, hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (*ClusterScalingScheduleCollector, error) {
+func NewClusterScalingScheduleCollector(store Store, defaultScalingWindow time.Duration, rampSteps int, now Now, hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (*ClusterScalingScheduleCollector, error) {
 	return &ClusterScalingScheduleCollector{
 		scalingScheduleCollector{
-			store:           store,
-			now:             now,
-			objectReference: config.ObjectReference,
-			hpa:             hpa,
-			metric:          config.Metric,
-			interval:        interval,
-			config:          *config,
+			store:                store,
+			now:                  now,
+			objectReference:      config.ObjectReference,
+			hpa:                  hpa,
+			metric:               config.Metric,
+			interval:             interval,
+			config:               *config,
+			defaultScalingWindow: defaultScalingWindow,
+			rampSteps:            rampSteps,
 		},
 	}, nil
 }
@@ -188,7 +203,7 @@ func (c *ScalingScheduleCollector) GetMetrics() ([]CollectedMetric, error) {
 	if !ok {
 		return nil, ErrNotScalingScheduleFound
 	}
-	return calculateMetrics(scalingSchedule.Spec.Schedules, c.now(), c.objectReference, c.metric)
+	return calculateMetrics(scalingSchedule.Spec, c.defaultScalingWindow, c.rampSteps, c.now(), c.objectReference, c.metric)
 }
 
 // GetMetrics is the main implementation for collector.Collector interface
@@ -221,7 +236,7 @@ func (c *ClusterScalingScheduleCollector) GetMetrics() ([]CollectedMetric, error
 		clusterScalingSchedule = v1.ClusterScalingSchedule(*scalingSchedule)
 	}
 
-	return calculateMetrics(clusterScalingSchedule.Spec.Schedules, c.now(), c.objectReference, c.metric)
+	return calculateMetrics(clusterScalingSchedule.Spec, c.defaultScalingWindow, c.rampSteps, c.now(), c.objectReference, c.metric)
 }
 
 // Interval returns the interval at which the collector should run.
@@ -234,9 +249,17 @@ func (c *ClusterScalingScheduleCollector) Interval() time.Duration {
 	return c.interval
 }
 
-func calculateMetrics(schedules []v1.Schedule, now time.Time, objectReference custom_metrics.ObjectReference, metric autoscalingv2.MetricIdentifier) ([]CollectedMetric, error) {
-	value := 0
-	for _, schedule := range schedules {
+func calculateMetrics(spec v1.ScalingScheduleSpec, defaultScalingWindow time.Duration, rampSteps int, now time.Time, objectReference custom_metrics.ObjectReference, metric autoscalingv2.MetricIdentifier) ([]CollectedMetric, error) {
+	scalingWindowDuration := defaultScalingWindow
+	if spec.ScalingWindowDurationMinutes != nil {
+		scalingWindowDuration = time.Duration(*spec.ScalingWindowDurationMinutes) * time.Minute
+	}
+	if scalingWindowDuration < 0 {
+		return nil, fmt.Errorf("scaling window duration cannot be negative")
+	}
+
+	value := int64(0)
+	for _, schedule := range spec.Schedules {
 		switch schedule.Type {
 		case v1.RepeatingSchedule:
 			location, err := time.LoadLocation(schedule.Period.Timezone)
@@ -269,9 +292,7 @@ func calculateMetrics(schedules []v1.Schedule, now time.Time, objectReference cu
 						parsedStartTime.Nanosecond(),
 						location,
 					)
-					if within(now, scheduledTime, schedule.DurationMinutes) && schedule.Value > value {
-						value = schedule.Value
-					}
+					value = maxInt64(value, valueForEntry(now, scheduledTime, schedule.Duration(), scalingWindowDuration, rampSteps, schedule.Value))
 					break
 				}
 			}
@@ -280,9 +301,8 @@ func calculateMetrics(schedules []v1.Schedule, now time.Time, objectReference cu
 			if err != nil {
 				return nil, ErrInvalidScheduleDate
 			}
-			if within(now, scheduledTime, schedule.DurationMinutes) && schedule.Value > value {
-				value = schedule.Value
-			}
+
+			value = maxInt64(value, valueForEntry(now, scheduledTime, schedule.Duration(), scalingWindowDuration, rampSteps, schedule.Value))
 		}
 	}
 
@@ -293,17 +313,56 @@ func calculateMetrics(schedules []v1.Schedule, now time.Time, objectReference cu
 			Custom: custom_metrics.MetricValue{
 				DescribedObject: objectReference,
 				Timestamp:       metav1.Time{Time: now},
-				Value:           *resource.NewMilliQuantity(int64(value*1000), resource.DecimalSI),
+				Value:           *resource.NewMilliQuantity(value*1000, resource.DecimalSI),
 				Metric:          custom_metrics.MetricIdentifier(metric),
 			},
 		},
 	}, nil
 }
 
-// within receive two time.Time and a number of minutes. It returns true
-// if the first given time, instant, is within the period of the second
-// given time (start) plus the given number of minutes.
-func within(instant, start time.Time, minutes int) bool {
-	return (instant.After(start) || instant.Equal(start)) &&
-		instant.Before(start.Add(time.Duration(minutes)*time.Minute))
+func valueForEntry(timestamp time.Time, startTime time.Time, entryDuration time.Duration, scalingWindowDuration time.Duration, rampSteps int, value int64) int64 {
+	scaleUpStart := startTime.Add(-scalingWindowDuration)
+	endTime := startTime.Add(entryDuration)
+	scaleUpEnd := endTime.Add(scalingWindowDuration)
+
+	if between(timestamp, startTime, endTime) {
+		return value
+	}
+	if between(timestamp, scaleUpStart, startTime) {
+		return scaledValue(timestamp, scaleUpStart, scalingWindowDuration, rampSteps, value)
+	}
+	if between(timestamp, endTime, scaleUpEnd) {
+		return scaledValue(scaleUpEnd, timestamp, scalingWindowDuration, rampSteps, value)
+	}
+	return 0
+}
+
+// The HPA has a rule to do not scale up or down if the change in the
+// metric is less than 10% (by default) of the current value. We will
+// use buckets of time using the floor of each as the returned metric.
+// Any config greater or equal to 10 buckets must guarantee changes
+// bigger than 10%.
+func scaledValue(timestamp time.Time, startTime time.Time, scalingWindowDuration time.Duration, rampSteps int, value int64) int64 {
+	if scalingWindowDuration == 0 {
+		return 0
+	}
+
+	steps := float64(rampSteps)
+
+	requiredPercentage := math.Abs(float64(timestamp.Sub(startTime))) / float64(scalingWindowDuration)
+	return int64(math.Floor(requiredPercentage*steps) * (float64(value) / steps))
+}
+
+func between(timestamp, start, end time.Time) bool {
+	if timestamp.Before(start) {
+		return false
+	}
+	return timestamp.Before(end)
+}
+
+func maxInt64(i1, i2 int64) int64 {
+	if i1 > i2 {
+		return i1
+	}
+	return i2
 }

pkg/collector/scaling_schedule_collector_test.go

@@ -12,7 +12,11 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
-const hHMMFormat = "15:04"
+const (
+	hHMMFormat                   = "15:04"
+	defaultScalingWindowDuration = 1 * time.Minute
+	defaultRampSteps             = 10
+)
 
 type schedule struct {
 	kind      string
@@ -21,7 +25,7 @@ type schedule struct {
 	days      []v1.ScheduleDay
 	timezone  string
 	duration  int
-	value     int
+	value     int64
 }
 
 func TestScalingScheduleCollector(t *testing.T) {
@@ -37,11 +41,15 @@ func TestScalingScheduleCollector(t *testing.T) {
 		return uTCNow
 	}
 
+	tenMinutes := int64(10)
+
 	for _, tc := range []struct {
-		msg           string
-		schedules     []schedule
-		expectedValue int
-		err           error
+		msg                          string
+		schedules                    []schedule
+		scalingWindowDurationMinutes *int64
+		expectedValue                int64
+		err                          error
+		rampSteps                    int
 	}{
 		{
 			msg: "Return the right value for one time config",
@@ -80,7 +88,70 @@ func TestScalingScheduleCollector(t *testing.T) {
 			expectedValue: 100,
 		},
 		{
-			msg: "Return the default value (0) for one time config - 30 seconds after",
+			msg: "Return the scaled value (60) for one time config - 20 seconds before starting",
+			schedules: []schedule{
+				{
+					date:     nowTime.Add(time.Second * 20).Format(time.RFC3339),
+					kind:     "OneTime",
+					duration: 45,
+					value:    100,
+				},
+			},
+			expectedValue: 60,
+		},
+		{
+			msg: "Return the scaled value (60) for one time config - 20 seconds after",
+			schedules: []schedule{
+				{
+					date:     nowTime.Add(-time.Minute * 45).Add(-time.Second * 20).Format(time.RFC3339),
+					kind:     "OneTime",
+					duration: 45,
+					value:    100,
+				},
+			},
+			expectedValue: 60,
+		},
+		{
+			msg: "10 steps (default) return 90% of the metric, even 1 second before",
+			schedules: []schedule{
+				{
+					date:     nowTime.Add(time.Second * 1).Format(time.RFC3339),
+					kind:     "OneTime",
+					duration: 45,
+					value:    100,
+				},
+			},
+			expectedValue: 90,
+		},
+		{
+			msg: "5 steps return 80% of the metric, even 1 second before",
+			schedules: []schedule{
+				{
+					date:     nowTime.Add(time.Second * 1).Format(time.RFC3339),
+					kind:     "OneTime",
+					duration: 45,
+					value:    100,
+				},
+			},
+			expectedValue: 80,
+			rampSteps:     5,
+		},
+		{
+			msg:                          "Return the scaled value (90) for one time config with a custom scaling window - 30 seconds before starting",
+			scalingWindowDurationMinutes: &tenMinutes,
+			schedules: []schedule{
+				{
+					date:     nowTime.Add(time.Second * 30).Format(time.RFC3339),
+					kind:     "OneTime",
+					duration: 45,
+					value:    100,
+				},
+			},
+			expectedValue: 90,
+		},
+		{
+			msg:                          "Return the scaled value (90) for one time config with a custom scaling window - 30 seconds after",
+			scalingWindowDurationMinutes: &tenMinutes,
 			schedules: []schedule{
 				{
 					date:     nowTime.Add(-time.Minute * 45).Add(-time.Second * 30).Format(time.RFC3339),
@@ -89,7 +160,7 @@ func TestScalingScheduleCollector(t *testing.T) {
 					value:    100,
 				},
 			},
-			expectedValue: 0,
+			expectedValue: 90,
 		},
 		{
 			msg: "Return the default value (0) for one time config not started yet (20 minutes before)",
@@ -427,17 +498,22 @@ func TestScalingScheduleCollector(t *testing.T) {
 			scalingScheduleName := "my_scaling_schedule"
 			namespace := "default"
 
+			rampSteps := tc.rampSteps
+			if rampSteps == 0 {
+				rampSteps = defaultRampSteps
+			}
+
 			schedules := getSchedules(tc.schedules)
-			store := newMockStore(scalingScheduleName, namespace, schedules)
-			plugin, err := NewScalingScheduleCollectorPlugin(store, now)
+			store := newMockStore(scalingScheduleName, namespace, tc.scalingWindowDurationMinutes, schedules)
+			plugin, err := NewScalingScheduleCollectorPlugin(store, now, defaultScalingWindowDuration, rampSteps)
 			require.NoError(t, err)
 
-			clusterStore := newClusterMockStore(scalingScheduleName, schedules)
-			clusterPlugin, err := NewClusterScalingScheduleCollectorPlugin(clusterStore, now)
+			clusterStore := newClusterMockStore(scalingScheduleName, tc.scalingWindowDurationMinutes, schedules)
+			clusterPlugin, err := NewClusterScalingScheduleCollectorPlugin(clusterStore, now, defaultScalingWindowDuration, rampSteps)
 			require.NoError(t, err)
 
-			clusterStoreFirstRun := newClusterMockStoreFirstRun(scalingScheduleName, schedules)
-			clusterPluginFirstRun, err := NewClusterScalingScheduleCollectorPlugin(clusterStoreFirstRun, now)
+			clusterStoreFirstRun := newClusterMockStoreFirstRun(scalingScheduleName, tc.scalingWindowDurationMinutes, schedules)
+			clusterPluginFirstRun, err := NewClusterScalingScheduleCollectorPlugin(clusterStoreFirstRun, now, defaultScalingWindowDuration, rampSteps)
 			require.NoError(t, err)
 
 			hpa := makeScalingScheduleHPA(namespace, scalingScheduleName)
@@ -505,14 +581,14 @@ func TestScalingScheduleObjectNotPresentReturnsError(t *testing.T) {
 		make(map[string]interface{}),
 		getByKeyFn,
 	}
-	plugin, err := NewScalingScheduleCollectorPlugin(store, time.Now)
+	plugin, err := NewScalingScheduleCollectorPlugin(store, time.Now, defaultScalingWindowDuration, defaultRampSteps)
 	require.NoError(t, err)
 
 	clusterStore := mockStore{
 		make(map[string]interface{}),
 		getByKeyFn,
 	}
-	clusterPlugin, err := NewClusterScalingScheduleCollectorPlugin(clusterStore, time.Now)
+	clusterPlugin, err := NewClusterScalingScheduleCollectorPlugin(clusterStore, time.Now, defaultScalingWindowDuration, defaultRampSteps)
 	require.NoError(t, err)
 
 	hpa := makeScalingScheduleHPA("namespace", "scalingScheduleName")
@@ -567,10 +643,10 @@ func TestReturnsErrorWhenStoreDoes(t *testing.T) {
 		},
 	}
 
-	plugin, err := NewScalingScheduleCollectorPlugin(store, time.Now)
+	plugin, err := NewScalingScheduleCollectorPlugin(store, time.Now, defaultScalingWindowDuration, defaultRampSteps)
 	require.NoError(t, err)
 
-	clusterPlugin, err := NewClusterScalingScheduleCollectorPlugin(store, time.Now)
+	clusterPlugin, err := NewClusterScalingScheduleCollectorPlugin(store, time.Now, defaultScalingWindowDuration, defaultRampSteps)
 	require.NoError(t, err)
 
 	hpa := makeScalingScheduleHPA("namespace", "scalingScheduleName")
@@ -615,7 +691,7 @@ func getByKeyFn(d map[string]interface{}, key string) (item interface{}, exists
 	return item, exists, nil
 }
 
-func newMockStore(name, namespace string, schedules []v1.Schedule) mockStore {
+func newMockStore(name, namespace string, scalingWindowDurationMinutes *int64, schedules []v1.Schedule) mockStore {
 	return mockStore{
 		map[string]interface{}{
 			fmt.Sprintf("%s/%s", namespace, name): &v1.ScalingSchedule{
@@ -623,7 +699,8 @@ func newMockStore(name, namespace string, schedules []v1.Schedule) mockStore {
 					Name: name,
 				},
 				Spec: v1.ScalingScheduleSpec{
-					Schedules: schedules,
+					ScalingWindowDurationMinutes: scalingWindowDurationMinutes,
+					Schedules:                    schedules,
 				},
 			},
 		},
@@ -631,7 +708,7 @@ func newMockStore(name, namespace string, schedules []v1.Schedule) mockStore {
 	}
 }
 
-func newClusterMockStore(name string, schedules []v1.Schedule) mockStore {
+func newClusterMockStore(name string, scalingWindowDurationMinutes *int64, schedules []v1.Schedule) mockStore {
 	return mockStore{
 		map[string]interface{}{
 			name: &v1.ClusterScalingSchedule{
@@ -639,7 +716,8 @@ func newClusterMockStore(name string, schedules []v1.Schedule) mockStore {
 					Name: name,
 				},
 				Spec: v1.ScalingScheduleSpec{
-					Schedules: schedules,
+					ScalingWindowDurationMinutes: scalingWindowDurationMinutes,
+					Schedules:                    schedules,
 				},
 			},
 		},
@@ -650,7 +728,7 @@ func newClusterMockStore(name string, schedules []v1.Schedule) mockStore {
 // The cache.Store returns the v1.ClusterScalingSchedule items as
 // v1.ScalingSchedule when it first lists it. When it's update it
 // asserts it correctly to the v1.ClusterScalingSchedule type.
-func newClusterMockStoreFirstRun(name string, schedules []v1.Schedule) mockStore {
+func newClusterMockStoreFirstRun(name string, scalingWindowDurationMinutes *int64, schedules []v1.Schedule) mockStore {
 	return mockStore{
 		map[string]interface{}{
 			name: &v1.ScalingSchedule{
@@ -658,7 +736,8 @@ func newClusterMockStoreFirstRun(name string, schedules []v1.Schedule) mockStore
 					Name: name,
 				},
 				Spec: v1.ScalingScheduleSpec{
-					Schedules: schedules,
+					ScalingWindowDurationMinutes: scalingWindowDurationMinutes,
+					Schedules:                    schedules,
 				},
 			},
 		},

pkg/server/start.go

@@ -128,6 +128,8 @@ func NewCommandStartAdapterServer(stopCh <-chan struct{}) *cobra.Command {
 	flags.DurationVar(&o.GCInterval, "garbage-collector-interval", 10*time.Minute, "Interval to clean up metrics that are stored in in-memory cache.")
 	flags.BoolVar(&o.ScalingScheduleMetrics, "scaling-schedule", o.ScalingScheduleMetrics, ""+
 		"whether to enable time-based ScalingSchedule metrics")
+	flags.DurationVar(&o.DefaultScheduledScalingWindow, "scaling-schedule-default-scaling-window", 10*time.Minute, "Default rampup and rampdown window duration for ScalingSchedules")
+	flags.IntVar(&o.RampSteps, "scaling-schedule-ramp-steps", 10, "Number of steps used to rampup and rampdown ScalingSchedules. It's used to guarantee won't avoid reaching the max scaling due to the 10% minimum change rule.")
 	return cmd
 }
 
@@ -293,7 +295,7 @@ func (o AdapterServerOptions) RunCustomMetricsAdapterServer(stopCh <-chan struct
 		)
 		go reflector.Run(ctx.Done())
 
-		clusterPlugin, err := collector.NewClusterScalingScheduleCollectorPlugin(clusterScalingSchedulesStore, time.Now)
+		clusterPlugin, err := collector.NewClusterScalingScheduleCollectorPlugin(clusterScalingSchedulesStore, time.Now, o.DefaultScheduledScalingWindow, o.RampSteps)
 		if err != nil {
 			return fmt.Errorf("unable to create ClusterScalingScheduleCollector plugin: %v", err)
 		}
@@ -302,7 +304,7 @@ func (o AdapterServerOptions) RunCustomMetricsAdapterServer(stopCh <-chan struct
 			return fmt.Errorf("failed to register ClusterScalingSchedule object collector plugin: %v", err)
 		}
 
-		plugin, err := collector.NewScalingScheduleCollectorPlugin(scalingSchedulesStore, time.Now)
+		plugin, err := collector.NewScalingScheduleCollectorPlugin(scalingSchedulesStore, time.Now, o.DefaultScheduledScalingWindow, o.RampSteps)
 		if err != nil {
 			return fmt.Errorf("unable to create ScalingScheduleCollector plugin: %v", err)
 		}
@@ -428,4 +430,8 @@ type AdapterServerOptions struct {
 	GCInterval time.Duration
 	// Time-based scaling based on the CRDs ScheduleScaling and ClusterScheduleScaling.
 	ScalingScheduleMetrics bool
+	// Default ramp-up/ramp-down window duration for scheduled metrics
+	DefaultScheduledScalingWindow time.Duration
+	// Number of steps utilized during the rampup and rampdown for scheduled metrics
+	RampSteps int
 }