Pod定时伸缩，即CronHPA是Kubernetes中Pod水平扩展功能的一种，Kubernetes中的HPA是基于监控度量来定义并驱动Pod水平扩展缩容的，而CronHPA是根据crontab的方式，定期性的对Pod水平进行扩展缩容操作。
CronHPA支持任意规模类型资源的扩展缩容操作，其中包括Deployment和StatefulSet等。
使用场景
通过运维经验积累掌握负载规律后，可以使用CronHPA实现定期自动扩展缩容操作，以应对可预期的业务需求。
使用说明
前提条件
您已使用金山云容器服务服务创建一个正常运行的Kubernetes集群，关于如何创建集群，请参见创建集群。
CronHPA插件安装
- 进入容器集群内任意节点，创建cron-hpa.yaml
$ kubectl apply -f cron-hpa.yaml
- cron-hpa.yaml如下：
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
creationTimestamp: null
labels:
controller-tools.k8s.io: "1.0"
name: cronhorizontalpodautoscalers.autoscaling.kce.ksyun.com
spec:
group: autoscaling.kce.ksyun.com
names:
kind: CronHorizontalPodAutoscaler
plural: cronhorizontalpodautoscalers
shortNames:
- cronhpa
scope: Namespaced
validation:
openAPIV3Schema:
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/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/api-conventions.md#types-kinds'
type: string
metadata:
type: object
spec:
properties:
jobs:
items:
properties:
name:
type: string
schedule:
type: string
targetSize:
format: int32
type: integer
required:
- name
- schedule
- targetSize
type: object
type: array
scaleTargetRef:
description: 'INSERT ADDITIONAL SPEC FIELDS - desired state of cluster
Important: Run "make" to regenerate code after modifying this file'
properties:
apiVersion:
type: string
kind:
type: string
name:
type: string
required:
- apiVersion
- kind
- name
type: object
required:
- scaleTargetRef
- jobs
type: object
status:
properties:
conditions:
description: 'INSERT ADDITIONAL STATUS FIELD - define observed state
of cluster Important: Run "make" to regenerate code after modifying
this file'
items:
properties:
jobId:
type: string
lastProbeTime:
format: date-time
type: string
message:
description: Human readable message indicating details about last
transition.
type: string
name:
description: Type of job condition, Complete or Failed.
type: string
schedule:
type: string
state:
type: string
required:
- name
- jobId
- schedule
- state
- lastProbeTime
- message
type: object
type: array
required:
- conditions
type: object
version: v1beta1
status:
acceptedNames:
kind: ""
plural: ""
conditions: []
storedVersions: []
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: kubernetes-cronhpa-controller-role
rules:
- apiGroups: [""]
resources: ["*"]
verbs:
- get
- list
- watch
- update
- apiGroups:
- extensions
resources: ["*"]
verbs:
- get
- list
- watch
- update
- apiGroups:
- apps
resources: ["*"]
verbs:
- get
- list
- watch
- update
- apiGroups: [""]
resources: ["events"]
verbs:
- get
- list
- watch
- create
- update
- patch
- apiGroups: [""]
resources: ["configmaps"]
verbs:
- get
- create
- update
- apiGroups:
- autoscaling.kce.ksyun.com
resources:
- cronhorizontalpodautoscalers
verbs:
- get
- list
- watch
- create
- update
- patch
- apiGroups:
- autoscaling
resources:
- horizontalpodautoscalers
verbs:
- get
- list
- watch
- create
- update
- patch
- delete
- apiGroups:
- admissionregistration.k8s.io
resources:
- mutatingwebhookconfigurations
- validatingwebhookconfigurations
verbs:
- get
- list
- watch
- create
- update
- patch
- delete
- apiGroups:
- apps.kruise.io
resources:
- statefulsets/scale
- uniteddeployments/scale
- clonesets/scale
verbs:
- get
- list
- watch
- update
- patch
- apiGroups:
- autoscaling.kce.ksyun.com
resources:
- elasticworkloads/scale
verbs:
- get
- list
- watch
- update
- patch
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: kubernetes-cronhpa-controller
namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
creationTimestamp: null
name: kubernetes-cronhpa-controller-rolebinding
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: kubernetes-cronhpa-controller-role
subjects:
- kind: ServiceAccount
name: kubernetes-cronhpa-controller
namespace: kube-system
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: kubernetes-cronhpa-controller
namespace: kube-system
labels:
app: kubernetes-cronhpa-controller
controller-tools.k8s.io: "2.0"
spec:
replicas: 1 # The default is primary and standby mode (currently cold standby)
selector:
matchLabels:
app: kubernetes-cronhpa-controller
controller-tools.k8s.io: "2.0"
template:
metadata:
labels:
app: kubernetes-cronhpa-controller
controller-tools.k8s.io: "2.0"
spec:
containers:
- image: hub.kce.ksyun.com/ksyun/kubernetes-cronhpa-controller:v1.0.0
imagePullPolicy: Always
name: kubernetes-cronhpa-controller
env:
- name: TZ
value: "Asia/Shanghai"
resources:
limits:
cpu: 100m
memory: 100Mi
requests:
cpu: 100m
memory: 100Mi
serviceAccount: kubernetes-cronhpa-controller
- 查看插件是否安装成功
# 查看自定义资源是否安装
$ kubectl api-resources | grep cronhpa
cronhorizontalpodautoscalers cronhpa autoscaling.kce.ksyun.com true CronHorizontalPodAutoscaler
# 查看CronHPA controller是否安装
$ kubectl get deploy kubernetes-cronhpa-controller -n kube-system
NAME READY UP-TO-DATE AVAILABLE AGE
kubernetes-cronhpa-controller 1/1 1 1 4m11s
功能测试
成功安装CronHPA插件后，以下举例如何部署具体的cronhpa并进行测试。
- 部署测试对象与cronhpa。
$ kubectl apply -f cronhpa-example.yaml
- cronhpa-example.yaml如下：
---
apiVersion: apps/v1 # for versions before 1.8.0 use apps/v1beta1
kind: Deployment
metadata:
name: nginx-deployment-basic
labels:
app: nginx
spec:
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9 # replace it with your exactly <image_name:tags>
ports:
- containerPort: 80
---
apiVersion: autoscaling.kce.ksyun.com/v1beta1
kind: CronHorizontalPodAutoscaler
metadata:
labels:
controller-tools.k8s.io: "1.0"
name: cronhpa-sample
spec:
scaleTargetRef:
apiVersion: apps/v1beta2
kind: Deployment
name: nginx-deployment-basic
excludeDates:
- "* * * 15 11 *" # exclude November 15th
- "* * * * * 5" # exclude every Friday
jobs:
- name: "scale-down"
schedule: "30 */1 * * * *" # 每分钟的第30秒，将deployment/nginx-deployment-basic 副本数调整为 1
targetSize: 1
- name: "scale-up"
schedule: "0 */1 * * * *" # 每分钟的第0秒，将deployment/nginx-deployment-basic 副本数调整为 3
targetSize: 3
- 各字段的解释说明如下：
| 字段 | 说明 | 备注 | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| scaleTargetRef | scaleTargetRef指定去扩大缩容对象。如果对象支持scale子资源，cronhpa即可支持 | 除scale子资源外，还支持HPA，以稳定性优先原则，在扩缩容时，以cronHPA与HPA设定副本数中较大值作为扩缩容最终值 | ||||||||||||||||||||||||||||
| excludeDates | excludeDates 是日期数组。当遇到符合excludeDates 描述的日期时任务将会被跳过 | 最小单位为天 | ||||||||||||||||||||||||||||
| jobs | 支持在一个规格中设置多个cronhpa任务。每个cronhpa任务可以配置以下分段： - name：它在一个cronhpa中应是唯一的，这样就可以通过name 来区分不同的任务 - schedule：它的策略和crontab类似 - targetSize：到计划时间时，您想扩缩容到的Pod的数量 - runOnce：如果runOnce 设置为true ，那么任务将只执行一次，第一次执行完则exit | cron表达式格式：
|
- 查看 cronhpa 实例
$ kubectl get cronhpa
NAME AGE
cronhpa-sample 15s
- 查看cronhpa/cronhpa-sample详情
$ kubectl describe cronhpa cronhpa-sample
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Succeed 8m31s cron-horizontal-pod-autoscaler cron hpa job scale-down executed successfully. current replicas:2, desired replicas:1.
Normal Succeed 31s (x8 over 7m31s) cron-horizontal-pod-autoscaler cron hpa job scale-down executed successfully. current replicas:3, desired replicas:1.
Normal Succeed 1s (x9 over 8m1s) cron-horizontal-pod-autoscaler cron hpa job scale-up executed successfully. current replicas:1, desired replicas:3.
- 查看 deploy/nginx-deployment-basic 副本数状态变化情况
$ kubectl get deploy nginx-deployment-basic -w
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment-basic 1/1 1 1 3m31s
nginx-deployment-basic 1/3 1 1 3m48s
nginx-deployment-basic 1/3 1 1 3m48s
nginx-deployment-basic 1/3 3 1 3m48s
nginx-deployment-basic 2/3 3 2 3m50s
nginx-deployment-basic 3/3 3 3 3m50s
nginx-deployment-basic 3/1 3 3 4m18s
nginx-deployment-basic 3/1 3 3 4m18s
nginx-deployment-basic 1/1 1 1 4m18s
nginx-deployment-basic 1/3 1 1 4m48s
nginx-deployment-basic 1/3 1 1 4m48s
nginx-deployment-basic 1/3 1 1 4m48s
nginx-deployment-basic 1/3 3 1 4m48s
nginx-deployment-basic 2/3 3 2 4m49s
nginx-deployment-basic 3/3 3 3 4m49s
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