Create ScalingSchedule collector

This commit adds two new collectors to the adapter:
- ClusterScalingScheduleCollector; and
- ScalingScheduleCollector

Also, it introduces the required collectors plugins, initialization
logic in the server startup, documentation and deployment example
(including the helm chart). A new config flag is created,
`-scaling-schedule`, and allows to enable and to disable the collection
of such metrics. It's disabled by default.

This collectors are the required logic to utilise the CRDs introduced in
the #284 pull request. It makes use of the kubernetes go-client
implementations of a [Store][0] and [Reflector][1].

[0]: https://pkg.go.dev/k8s.io/client-go/tools/cache#Store
[1]: https://pkg.go.dev/k8s.io/client-go/tools/cache#Reflector

Signed-off-by: Jonathan Juares Beber <jonathanbeber@gmail.com>

Dockerfile

@@ -1,6 +1,8 @@
 FROM registry.opensource.zalan.do/library/alpine-3.12:latest
 LABEL maintainer="Team Teapot @ Zalando SE <team-teapot@zalando.de>"
 
+RUN apk add --no-cache tzdata
+
 # add binary
 ADD build/linux/kube-metrics-adapter /
 

README.md

@@ -671,3 +671,121 @@ metric-config.<metricType>.<metricName>.<collectorType>/interval: "30s"
 
 The default is `60s` but can be reduced to let the adapter collect metrics more
 often.
+
+## ScalingSchedule Collectors
+
+The `ScalingSchedule` and `ClusterScalingSchedule` collectors allow
+collecting time-based metrics from the respective CRD objects specified
+in the HPA.
+
+### 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` |
+
+### Example
+
+This is an example of using the ScalingSchedule collectors to collect
+metrics from a deployed kind of the CRD. First, the schedule object:
+
+```yaml
+apiVersion: zalando.org/v1
+kind: ClusterScalingSchedule
+metadata:
+  name: "scheduling-event"
+spec:
+  schedules:
+  - type: OneTime
+    date: "2021-10-02T08:08:08+02:00"
+    durationMinutes: 30
+    value: 100
+  - type: Repeating
+    durationMinutes: 10
+    value: 120
+    period:
+      startTime: "15:45"
+      timezone: "Europe/Berlin"
+      days:
+      - Mon
+      - Wed
+      - Fri
+```
+
+This resource defines a scheduling event named `scheduling-event` with
+two schedules of the kind `ClusterScalingSchedule`.
+
+`ClusterScalingSchedule` objects aren't namespaced, what means it can be
+referenced by any HPA in any namespace in the cluster. `ScalingSchedule`
+have the exact same fields and behavior, but can be referenced just by
+HPAs in the same namespace. The schedules can have the type `Repeating`
+or `OneTime`.
+
+This example configuration will generate the following result: at
+`2021-10-02T08:08:08+02:00` for 30 minutes a metric with the value of
+100 will be returned. Every Monday, Wednesday and Friday, starting at 15
+hours and 45 minutes (Berlin time), a metric with the value of 120 will
+be returned for 10 minutes. It's not the case of this example, but if multiple
+schedules collide in time, the biggest value is returned.
+
+Check the CRDs definitions
+([ScalingSchedule](./docs/scaling_schedules_crd.yaml),
+[ClusterScalingSchedule](./docs/cluster_scaling_schedules_crd.yaml)) for
+a better understanding of the possible fields and their behavior.
+
+An HPA can reference the deployed `ClusterScalingSchedule` object as
+this example:
+
+```yaml
+apiVersion: autoscaling/v2beta2
+kind: HorizontalPodAutoscaler
+metadata:
+  name: "myapp-hpa"
+spec:
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: myapp
+  minReplicas: 1
+  maxReplicas: 15
+  metrics:
+  - type: Object
+    object:
+      describedObject:
+        apiVersion: zalando.org/v1
+        kind: ClusterScalingSchedule
+        name: "scheduling-event"
+      metric:
+        name: "scheduling-event"
+      target:
+        type: AverageValue
+        averageValue: "10"
+```
+
+The name of the metric is equal to the name of the referenced object.
+The `target.averageValue` in this example is set to 10. This value will
+be used by the HPA controller to define the desired number of pods,
+based on the metric obtained (check the [HPA algorithm
+details](https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/#algorithm-details)
+for more context). This HPA configuration explicitly says that each pod
+of this application supports 10 units of the `ClusterScalingSchedule`
+metric. Multiple applications can share the same
+`ClusterScalingSchedule` or `ScalingSchedule` event and have a different
+number of pods based on its `target.averageValue` configuration.
+
+In our specific example at `2021-10-02T08:08:08+02:00` as the metric has
+the value 100, this application will scale to 10 pods (100/10). Every
+Monday, Wednesday and Friday, starting at 15 hours and 45 minutes
+(Berlin time) the application will scale to 12 pods (120/10). Both
+scaling up will last at least the configured duration times of the
+schedules. After that, regular HPA scale down behavior applies.
+
+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/deployment.yaml

@@ -28,6 +28,7 @@ spec:
         - --prometheus-server=http://prometheus.kube-system.svc.cluster.local
         - --skipper-ingress-metrics
         - --aws-external-metrics
+        - --scaling-schedule
         env:
         - name: AWS_REGION
           value: eu-central-1

docs/helm/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v2
 name: kube-metrics-adapter
-version: 0.1.10
+version: 0.1.11
 description: kube-metrics-adapter helm chart
 home: https://github.com/zalando-incubator/kube-metrics-adapter
 maintainers:

docs/helm/templates/cluster_scaling_schedules_crd.yaml

@@ -0,0 +1,119 @@
+{{- if .Values.scalingSchedule.enabled }}
+apiVersion: apiextensions.k8s.io/v1
+kind: CustomResourceDefinition
+metadata:
+  annotations:
+    controller-gen.kubebuilder.io/version: v0.5.0
+  creationTimestamp: null
+  name: clusterscalingschedules.zalando.org
+spec:
+  group: zalando.org
+  names:
+    kind: ClusterScalingSchedule
+    listKind: ClusterScalingScheduleList
+    plural: clusterscalingschedules
+    singular: clusterscalingschedule
+  scope: Cluster
+  versions:
+  - name: v1
+    schema:
+      openAPIV3Schema:
+        description: ClusterScalingSchedule describes a cluster scoped time based
+          metric to be used in autoscaling operations.
+        properties:
+          apiVersion:
+            description: 'APIVersion defines the versioned schema of this representation
+              of an object. Servers should convert recognized schemas to the latest
+              internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources'
+            type: string
+          kind:
+            description: 'Kind is a string value representing the REST resource this
+              object represents. Servers may infer this from the endpoint the client
+              submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds'
+            type: string
+          metadata:
+            type: object
+          spec:
+            description: ScalingScheduleSpec is the spec part of the ScalingSchedule.
+            properties:
+              schedules:
+                description: 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 resource.
+                items:
+                  description: Schedule is the schedule details to be used inside
+                    a ScalingSchedule.
+                  properties:
+                    date:
+                      description: Defines the starting date of a OneTime schedule.
+                        It has to be a RFC3339 formated date.
+                      format: date-time
+                      type: string
+                    durationMinutes:
+                      description: The duration in minutes that the configured value
+                        will be returned for the defined schedule.
+                      type: integer
+                    period:
+                      description: Defines the details of a Repeating schedule.
+                      properties:
+                        days:
+                          description: The days that this schedule will be active.
+                          items:
+                            description: ScheduleDay represents the valid inputs for
+                              days in a SchedulePeriod.
+                            enum:
+                            - Sun
+                            - Mon
+                            - Tue
+                            - Wed
+                            - Thu
+                            - Fri
+                            - Sat
+                            type: string
+                          type: array
+                        startTime:
+                          description: The startTime has the format HH:MM
+                          pattern: (([0-1][0-9])|([2][0-3])):([0-5][0-9])
+                          type: string
+                        timezone:
+                          description: The location name corresponding to a file in
+                            the IANA Time Zone database, like Europe/Berlin.
+                          type: string
+                      required:
+                      - days
+                      - startTime
+                      - timezone
+                      type: object
+                    type:
+                      description: Defines if the schedule is a OneTime schedule or
+                        Repeating one. If OneTime, date has to be defined. If Repeating,
+                        Period has to be defined.
+                      enum:
+                      - OneTime
+                      - Repeating
+                      type: string
+                    value:
+                      description: The metric value that will be returned for the
+                        defined schedule.
+                      type: integer
+                  required:
+                  - durationMinutes
+                  - type
+                  - value
+                  type: object
+                type: array
+            required:
+            - schedules
+            type: object
+        required:
+        - spec
+        type: object
+    served: true
+    storage: true
+status:
+  acceptedNames:
+    kind: ""
+    plural: ""
+  conditions: []
+  storedVersions: []
+{{- end}}

docs/helm/templates/deployment.yaml

@@ -182,6 +182,9 @@ spec:
             {{- if .Values.zmon.tokenName }}
             - --zmon-token-name={{ .Values.zmon.tokenName }}
             {{- end}}
+            {{- if .Values.scalingSchedule.enabled }}
+            - --scaling-schedule
+            {{- end}}
           resources:
             limits:
               cpu: {{ .Values.resources.limits.cpu }}

docs/helm/templates/rbac.yaml

@@ -73,6 +73,17 @@ rules:
   - get
   - list
   - watch
+{{- if .Values.scalingSchedule.enabled }}
+- apiGroups:
+  - zalando.org
+  resources:
+  - clusterscalingschedules
+  - scalingschedules
+  verbs:
+  - get
+  - list
+  - watch
+{{- end}}
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRoleBinding

docs/helm/templates/scaling_schedules_crd.yaml

@@ -0,0 +1,119 @@
+{{- if .Values.scalingSchedule.enabled }}
+apiVersion: apiextensions.k8s.io/v1
+kind: CustomResourceDefinition
+metadata:
+  annotations:
+    controller-gen.kubebuilder.io/version: v0.5.0
+  creationTimestamp: null
+  name: scalingschedules.zalando.org
+spec:
+  group: zalando.org
+  names:
+    kind: ScalingSchedule
+    listKind: ScalingScheduleList
+    plural: scalingschedules
+    singular: scalingschedule
+  scope: Namespaced
+  versions:
+  - name: v1
+    schema:
+      openAPIV3Schema:
+        description: ScalingSchedule describes a namespaced time based metric to be
+          used in autoscaling operations.
+        properties:
+          apiVersion:
+            description: 'APIVersion defines the versioned schema of this representation
+              of an object. Servers should convert recognized schemas to the latest
+              internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources'
+            type: string
+          kind:
+            description: 'Kind is a string value representing the REST resource this
+              object represents. Servers may infer this from the endpoint the client
+              submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds'
+            type: string
+          metadata:
+            type: object
+          spec:
+            description: ScalingScheduleSpec is the spec part of the ScalingSchedule.
+            properties:
+              schedules:
+                description: 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 resource.
+                items:
+                  description: Schedule is the schedule details to be used inside
+                    a ScalingSchedule.
+                  properties:
+                    date:
+                      description: Defines the starting date of a OneTime schedule.
+                        It has to be a RFC3339 formated date.
+                      format: date-time
+                      type: string
+                    durationMinutes:
+                      description: The duration in minutes that the configured value
+                        will be returned for the defined schedule.
+                      type: integer
+                    period:
+                      description: Defines the details of a Repeating schedule.
+                      properties:
+                        days:
+                          description: The days that this schedule will be active.
+                          items:
+                            description: ScheduleDay represents the valid inputs for
+                              days in a SchedulePeriod.
+                            enum:
+                            - Sun
+                            - Mon
+                            - Tue
+                            - Wed
+                            - Thu
+                            - Fri
+                            - Sat
+                            type: string
+                          type: array
+                        startTime:
+                          description: The startTime has the format HH:MM
+                          pattern: (([0-1][0-9])|([2][0-3])):([0-5][0-9])
+                          type: string
+                        timezone:
+                          description: The location name corresponding to a file in
+                            the IANA Time Zone database, like Europe/Berlin.
+                          type: string
+                      required:
+                      - days
+                      - startTime
+                      - timezone
+                      type: object
+                    type:
+                      description: Defines if the schedule is a OneTime schedule or
+                        Repeating one. If OneTime, date has to be defined. If Repeating,
+                        Period has to be defined.
+                      enum:
+                      - OneTime
+                      - Repeating
+                      type: string
+                    value:
+                      description: The metric value that will be returned for the
+                        defined schedule.
+                      type: integer
+                  required:
+                  - durationMinutes
+                  - type
+                  - value
+                  type: object
+                type: array
+            required:
+            - schedules
+            type: object
+        required:
+        - spec
+        type: object
+    served: true
+    storage: true
+status:
+  acceptedNames:
+    kind: ""
+    plural: ""
+  conditions: []
+  storedVersions: []
+{{- end}}

docs/helm/values.yaml

@@ -92,3 +92,6 @@ resources:
   requests:
     cpu: 100m
     memory: 100Mi
+
+scalingSchedule:
+  enabled: false

docs/rbac.yaml

@@ -78,6 +78,15 @@ rules:
   - get
   - list
   - watch
+- apiGroups:
+  - zalando.org
+  resources:
+  - clusterscalingschedules
+  - scalingschedules
+  verbs:
+  - get
+  - list
+  - watch
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRoleBinding

pkg/collector/skipper_collector_test.go

@@ -332,7 +332,7 @@ func TestSkipperCollector(t *testing.T) {
 			err := makeIngress(client, tc.namespace, tc.ingressName, tc.backend, tc.hostnames, tc.backendWeights)
 			require.NoError(t, err)
 			plugin := makePlugin(tc.metric)
-			hpa := makeHPA(tc.namespace, tc.ingressName, tc.backend)
+			hpa := makeIngressHPA(tc.namespace, tc.ingressName, tc.backend)
 			config := makeConfig(tc.ingressName, tc.namespace, tc.backend, tc.fakedAverage)
 			_, err = newDeployment(client, tc.namespace, tc.backend, tc.replicas, tc.readyReplicas)
 			require.NoError(t, err)
@@ -387,7 +387,7 @@ func makeIngress(client kubernetes.Interface, namespace, ingressName, backend st
 	return err
 }
 
-func makeHPA(namespace, ingressName, backend string) *autoscalingv2.HorizontalPodAutoscaler {
+func makeIngressHPA(namespace, ingressName, backend string) *autoscalingv2.HorizontalPodAutoscaler {
 	return &autoscalingv2.HorizontalPodAutoscaler{
 		ObjectMeta: metav1.ObjectMeta{Namespace: namespace},
 		Spec: autoscalingv2.HorizontalPodAutoscalerSpec{

pkg/provider/metric_store.go

@@ -63,7 +63,8 @@ func (s *MetricStore) insertCustomMetric(value custom_metrics.MetricValue) {
 	s.Lock()
 	defer s.Unlock()
 
-	// TODO: handle this mapping nicer
+	// TODO: handle this mapping nicer. This information should be
+	// registered as the metrics are.
 	var groupResource schema.GroupResource
 	switch value.DescribedObject.Kind {
 	case "Pod":
@@ -71,7 +72,7 @@ func (s *MetricStore) insertCustomMetric(value custom_metrics.MetricValue) {
 			Resource: "pods",
 		}
 	case "Ingress":
-		// group can be either `extentions` or `networking.k8s.io`
+		// group can be either `extensions` or `networking.k8s.io`
 		group := "extensions"
 		gv, err := schema.ParseGroupVersion(value.DescribedObject.APIVersion)
 		if err == nil {
@@ -81,6 +82,26 @@ func (s *MetricStore) insertCustomMetric(value custom_metrics.MetricValue) {
 			Resource: "ingresses",
 			Group:    group,
 		}
+	case "ScalingSchedule":
+		group := "zalando.org"
+		gv, err := schema.ParseGroupVersion(value.DescribedObject.APIVersion)
+		if err == nil {
+			group = gv.Group
+		}
+		groupResource = schema.GroupResource{
+			Resource: "scalingschedules",
+			Group:    group,
+		}
+	case "ClusterScalingSchedule":
+		group := "zalando.org"
+		gv, err := schema.ParseGroupVersion(value.DescribedObject.APIVersion)
+		if err == nil {
+			group = gv.Group
+		}
+		groupResource = schema.GroupResource{
+			Resource: "clusterscalingschedules",
+			Group:    group,
+		}
 	}
 
 	metric := customMetricsStoredMetric{

pkg/provider/metrics_store_test.go

@@ -146,6 +146,120 @@ func TestInternalMetricStorage(t *testing.T) {
 				},
 			},
 		},
+		{
+			test: "insert/list/get a ScalingSchedule metric",
+			insert: collector.CollectedMetric{
+				Type: autoscalingv2.MetricSourceType("Object"),
+				Custom: custom_metrics.MetricValue{
+					Metric: newMetricIdentifier("scalingschedulename"),
+					Value:  *resource.NewQuantity(10, ""),
+					DescribedObject: custom_metrics.ObjectReference{
+						Name:       "metricObject",
+						Namespace:  "default",
+						Kind:       "ScalingSchedule",
+						APIVersion: "zalando.org/v1",
+					},
+				},
+			},
+			expectedFound: true,
+			list: []provider.CustomMetricInfo{
+				{
+					GroupResource: schema.GroupResource{
+						Group:    "zalando.org",
+						Resource: "scalingschedules",
+					},
+					Namespaced: true,
+					Metric:     "scalingschedulename",
+				},
+			},
+			byName: struct {
+				name types.NamespacedName
+				info provider.CustomMetricInfo
+			}{
+				name: types.NamespacedName{Name: "metricObject", Namespace: "default"},
+				info: provider.CustomMetricInfo{
+					GroupResource: schema.GroupResource{
+						Group:    "zalando.org",
+						Resource: "scalingschedules",
+					},
+					Namespaced: true,
+					Metric:     "scalingschedulename",
+				},
+			},
+			byLabel: struct {
+				namespace string
+				selector  labels.Selector
+				info      provider.CustomMetricInfo
+			}{
+				namespace: "default",
+				selector:  labels.Everything(),
+				info: provider.CustomMetricInfo{
+					GroupResource: schema.GroupResource{
+						Group:    "zalando.org",
+						Resource: "scalingschedules",
+					},
+					Namespaced: true,
+					Metric:     "scalingschedulename",
+				},
+			},
+		},
+		{
+			test: "insert/list/get a ClusterScalingSchedule metric",
+			insert: collector.CollectedMetric{
+				Type: autoscalingv2.MetricSourceType("Object"),
+				Custom: custom_metrics.MetricValue{
+					Metric: newMetricIdentifier("clusterscalingschedulename"),
+					Value:  *resource.NewQuantity(10, ""),
+					DescribedObject: custom_metrics.ObjectReference{
+						Name:       "metricObject",
+						Namespace:  "default", // The HPA namespace
+						Kind:       "ClusterScalingSchedule",
+						APIVersion: "zalando.org/v1",
+					},
+				},
+			},
+			expectedFound: true,
+			list: []provider.CustomMetricInfo{
+				{
+					GroupResource: schema.GroupResource{
+						Group:    "zalando.org",
+						Resource: "clusterscalingschedules",
+					},
+					Namespaced: true,
+					Metric:     "clusterscalingschedulename",
+				},
+			},
+			byName: struct {
+				name types.NamespacedName
+				info provider.CustomMetricInfo
+			}{
+				name: types.NamespacedName{Name: "metricObject", Namespace: "default"},
+				info: provider.CustomMetricInfo{
+					GroupResource: schema.GroupResource{
+						Group:    "zalando.org",
+						Resource: "clusterscalingschedules",
+					},
+					Namespaced: true,
+					Metric:     "clusterscalingschedulename",
+				},
+			},
+			byLabel: struct {
+				namespace string
+				selector  labels.Selector
+				info      provider.CustomMetricInfo
+			}{
+				namespace: "default",
+				selector:  labels.Everything(),
+				info: provider.CustomMetricInfo{
+					GroupResource: schema.GroupResource{
+						Group:    "zalando.org",
+						Resource: "clusterscalingschedules",
+					},
+					Namespaced: true,
+					Metric:     "clusterscalingschedulename",
+				},
+			},
+		},
 		{
 			test: "insert/list/get a non-namespaced resource metric",
 			insert: collector.CollectedMetric{

pkg/server/start.go

@@ -18,6 +18,7 @@ package server
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -31,15 +32,19 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/zalando-incubator/cluster-lifecycle-manager/pkg/credentials-loader/platformiam"
 	generatedopenapi "github.com/zalando-incubator/kube-metrics-adapter/pkg/api/generated/openapi"
+	v1 "github.com/zalando-incubator/kube-metrics-adapter/pkg/apis/zalando.org/v1"
+	"github.com/zalando-incubator/kube-metrics-adapter/pkg/client/clientset/versioned"
 	"github.com/zalando-incubator/kube-metrics-adapter/pkg/collector"
 	"github.com/zalando-incubator/kube-metrics-adapter/pkg/provider"
 	"github.com/zalando-incubator/kube-metrics-adapter/pkg/zmon"
 	"golang.org/x/oauth2"
+	"k8s.io/apimachinery/pkg/fields"
 	openapinamer "k8s.io/apiserver/pkg/endpoints/openapi"
 	genericapiserver "k8s.io/apiserver/pkg/server"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/cache"
 	"k8s.io/client-go/tools/clientcmd"
 	"k8s.io/klog"
 )
@@ -118,6 +123,8 @@ func NewCommandStartAdapterServer(stopCh <-chan struct{}) *cobra.Command {
 		"disregard failing to create collectors for incompatible HPAs")
 	flags.DurationVar(&o.MetricsTTL, "metrics-ttl", 15*time.Minute, "TTL for metrics that are stored in in-memory cache.")
 	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")
 	return cmd
 }
 
@@ -245,6 +252,49 @@ func (o AdapterServerOptions) RunCustomMetricsAdapterServer(stopCh <-chan struct
 		collectorFactory.RegisterExternalCollector([]string{collector.AWSSQSQueueLengthMetric}, collector.NewAWSCollectorPlugin(awsSessions))
 	}
 
+	if o.ScalingScheduleMetrics {
+		scalingScheduleClient, err := versioned.NewForConfig(clientConfig)
+		if err != nil {
+			return errors.New("unable to create [Cluster]ScalingSchedule.zalando.org/v1 client")
+		}
+
+		clusterScalingSchedulesStore := cache.NewStore(cache.MetaNamespaceKeyFunc)
+		clusterReflector := cache.NewReflector(
+			cache.NewListWatchFromClient(scalingScheduleClient.ZalandoV1().RESTClient(), "ClusterScalingSchedules", "", fields.Everything()),
+			&v1.ClusterScalingSchedule{},
+			clusterScalingSchedulesStore,
+			0,
+		)
+		go clusterReflector.Run(ctx.Done())
+
+		scalingSchedulesStore := cache.NewStore(cache.MetaNamespaceKeyFunc)
+		reflector := cache.NewReflector(
+			cache.NewListWatchFromClient(scalingScheduleClient.ZalandoV1().RESTClient(), "ScalingSchedules", "", fields.Everything()),
+			&v1.ScalingSchedule{},
+			scalingSchedulesStore,
+			0,
+		)
+		go reflector.Run(ctx.Done())
+
+		clusterPlugin, err := collector.NewClusterScalingScheduleCollectorPlugin(clusterScalingSchedulesStore, time.Now)
+		if err != nil {
+			return fmt.Errorf("unable to create ClusterScalingScheduleCollector plugin: %v", err)
+		}
+		err = collectorFactory.RegisterObjectCollector("ClusterScalingSchedule", "", clusterPlugin)
+		if err != nil {
+			return fmt.Errorf("failed to register ClusterScalingSchedule object collector plugin: %v", err)
+		}
+
+		plugin, err := collector.NewScalingScheduleCollectorPlugin(scalingSchedulesStore, time.Now)
+		if err != nil {
+			return fmt.Errorf("unable to create ScalingScheduleCollector plugin: %v", err)
+		}
+		err = collectorFactory.RegisterObjectCollector("ScalingSchedule", "", plugin)
+		if err != nil {
+			return fmt.Errorf("failed to register ScalingSchedule object collector plugin: %v", err)
+		}
+	}
+
 	hpaProvider := provider.NewHPAProvider(client, 30*time.Second, 1*time.Minute, collectorFactory, o.DisregardIncompatibleHPAs, o.MetricsTTL, o.GCInterval)
 
 	go hpaProvider.Run(ctx)
@@ -356,4 +406,6 @@ type AdapterServerOptions struct {
 	MetricsTTL time.Duration
 	// Interval to clean up metrics that are stored in in-memory cache
 	GCInterval time.Duration
+	// Time-based scaling based on the CRDs ScheduleScaling and ClusterScheduleScaling.
+	ScalingScheduleMetrics bool
 }