CronHPA

Cron Horizontal Pod Autoscaler(CronHPA)使我们能够使用crontab模式定期自动扩容工作负载(那些支持扩展子资源的负载，例如deployment、statefulset)。

CronHPA使用Cron格式进行编写，周期性地在给定的调度时间对工作负载进行扩缩容。

CronHPA 资源结构

CronHPA定义了一个新的CRD，cron-hpa-controller是该CRD对应的controller/operator，它解析CRD中的配置，根据系统时间信息对相应的工作负载进行扩缩容操作。

  1. // CronHPA represents a set of crontabs to set target's replicas.
  2. type CronHPA struct {
  3.     metav1.TypeMeta   `json:",inline"`
  4.     metav1.ObjectMeta `json:"metadata,omitempty"`
  6.     // Spec defines the desired identities of pods in this cronhpa.
  7.     Spec CronHPASpec `json:"spec,omitempty"`
  9.     // Status is the current status of pods in this CronHPA. This data
  10.     // may be out of date by some window of time.
  11.     Status CronHPAStatus `json:"status,omitempty"`
  12. }
  14. // A CronHPASpec is the specification of a CronHPA.
  15. type CronHPASpec struct {
  16.     // scaleTargetRef points to the target resource to scale
  17.     ScaleTargetRef autoscalingv2.CrossVersionObjectReference `json:"scaleTargetRef" protobuf:"bytes,1,opt,name=scaleTargetRef"`
  19.     Crons []Cron `json:"crons" protobuf:"bytes,2,opt,name=crons"`
  20. }
  22. type Cron struct {
  23.     // The schedule in Cron format, see https://en.wikipedia.org/wiki/Cron.
  24.     Schedule string `json:"schedule" protobuf:"bytes,1,opt,name=schedule"`
  26.     TargetReplicas int32 `json:"targetReplicas" protobuf:"varint,2,opt,name=targetReplicas"`
  27. }
  29. // CronHPAStatus represents the current state of a CronHPA.
  30. type CronHPAStatus struct {
  31.     // Information when was the last time the schedule was successfully scheduled.
  32.     // +optional
  33.     LastScheduleTime *metav1.Time `json:"lastScheduleTime,omitempty" protobuf:"bytes,2,opt,name=lastScheduleTime"`
  34. }
  36. // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
  38. // CronHPAList is a collection of CronHPA.
  39. type CronHPAList struct {
  40.     metav1.TypeMeta `json:",inline"`
  41.     metav1.ListMeta `json:"metadata,omitempty"`
  42.     Items           []CronHPA `json:"items"`
  43. }

使用示例

指定deployment每周五20点扩容到60个实例，周日23点缩容到30个实例

  1. apiVersion: extensions.tkestack.io/v1
  2. kind: CronHPA
  3. metadata:
  4.   name: example-cron-hpa
  5. spec:
  6.   scaleTargetRef:
  7.     apiVersion: apps/v1
  8.     kind: Deployment
  9.     name: demo-deployment
  10.   crons:
  11.     - schedule: "0 20 * * 5"
  12.       targetReplicas: 60
  13.     - schedule: "0 23 * * 7"
  14.       targetReplicas: 30

指定deployment每天8点到9点，19点到21点扩容到60，其他时间点恢复到10

  1. apiVersion: extensions.tkestack.io/v1
  2. kind: CronHPA
  3. metadata:
  4.   name: web-servers-cronhpa
  5. spec:
  6.   scaleTargetRef:
  7.     apiVersion: apps/v1
  8.     kind: Deployment
  9.     name: web-servers
  10.   crons:
  11.     - schedule: "0 8 * * *"
  12.       targetReplicas: 60
  13.     - schedule: "0 9 * * *"
  14.       targetReplicas: 10
  15.     - schedule: "0 19 * * *"
  16.       targetReplicas: 60
  17.     - schedule: "0 21 * * *"
  18.       targetReplicas: 10

查看cronhpa

  1. # kubectl get cronhpa
  2. NAME               AGE
  3. example-cron-hpa   104s
  5. # kubectl get cronhpa example-cron-hpa -o yaml
  6. apiVersion: extensions.tkestack.io/v1
  7. kind: CronHPA
  8. ...
  9. spec:
  10.   crons:
  11.   - schedule: 0 20 * * 5
  12.     targetReplicas: 60
  13.   - schedule: 0 23 * * 7
  14.     targetReplicas: 30
  15.   scaleTargetRef:
  16.     apiVersion: apps/v1
  17.     kind: Deployment
  18.     name: demo-deployment

删除cronhpa

  1. kubectl delete cronhpa example-cron-hpa