kubernetes-cronhpa-controller
is a kubernetes cron horizontal pod autoscaler controller using crontab
like scheme. You can use CronHorizontalPodAutoscaler
with any kind object defined in kubernetes which support scale
subresource(such as Deployment
and StatefulSet
).
- install CRD
kubectl apply -f config/crds/autoscaling_v1beta1_cronhorizontalpodautoscaler.yaml
- install RBAC settings
# create ClusterRole
kubectl apply -f config/rbac/rbac_role.yaml
# create ClusterRolebinding and ServiceAccount
kubectl apply -f config/rbac/rbac_role_binding.yaml
- deploy kubernetes-cronhpa-controller
kubectl apply -f config/deploy/deploy.yaml
- verify installation
kubectl get deploy kubernetes-cronhpa-controller -n kube-system -o wide
➜ kubernetes-cronhpa-controller git:(master) ✗ kubectl get deploy kubernetes-cronhpa-controller -n kube-system
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
kubernetes-cronhpa-controller 1 1 1 1 49s
Please try out the examples in the examples folder.
- Deploy sample workload and cronhpa
kubectl apply -f examples/deployment_cronhpa.yaml
- Check deployment replicas
kubectl get deploy nginx-deployment-basic
➜ kubernetes-cronhpa-controller git:(master) ✗ kubectl get deploy nginx-deployment-basic
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment-basic 2 2 2 2 9s
- Describe cronhpa status
kubectl describe cronhpa cronhpa-sample
Name: cronhpa-sample
Namespace: default
Labels: controller-tools.k8s.io=1.0
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"autoscaling.alibabacloud.com/v1beta1","kind":"CronHorizontalPodAutoscaler","metadata":{"annotations":{},"labels":{"controll...
API Version: autoscaling.alibabacloud.com/v1beta1
Kind: CronHorizontalPodAutoscaler
Metadata:
Creation Timestamp: 2019-04-14T10:42:38Z
Generation: 1
Resource Version: 4017247
Self Link: /apis/autoscaling.alibabacloud.com/v1beta1/namespaces/default/cronhorizontalpodautoscalers/cronhpa-sample
UID: 05e41c95-5ea2-11e9-8ce6-00163e12e274
Spec:
Jobs:
Name: scale-down
Schedule: 30 */1 * * * *
Target Size: 1
Name: scale-up
Schedule: 0 */1 * * * *
Target Size: 3
Scale Target Ref:
API Version: apps/v1beta2
Kind: Deployment
Name: nginx-deployment-basic
Status:
Conditions:
Job Id: 38e79271-9a42-4131-9acd-1f5bfab38802
Last Probe Time: 2019-04-14T10:43:02Z
Message:
Name: scale-down
Schedule: 30 */1 * * * *
State: Submitted
Job Id: a7db95b6-396a-4753-91d5-23c2e73819ac
Last Probe Time: 2019-04-14T10:43:02Z
Message:
Name: scale-up
Schedule: 0 */1 * * * *
State: Submitted
Events: <none>
if the State
of cronhpa job is Succeed
that means the last execution is successful. Submitted
means the cronhpa job is submitted to the cron engine but haven't be executed so far. Wait for 30s seconds and check the status.
➜ kubernetes-cronhpa-controller git:(master) kubectl describe cronhpa cronhpa-sample
Name: cronhpa-sample
Namespace: default
Labels: controller-tools.k8s.io=1.0
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"autoscaling.alibabacloud.com/v1beta1","kind":"CronHorizontalPodAutoscaler","metadata":{"annotations":{},"labels":{"controll...
API Version: autoscaling.alibabacloud.com/v1beta1
Kind: CronHorizontalPodAutoscaler
Metadata:
Creation Timestamp: 2019-04-15T06:41:44Z
Generation: 1
Resource Version: 15673230
Self Link: /apis/autoscaling.alibabacloud.com/v1beta1/namespaces/default/cronhorizontalpodautoscalers/cronhpa-sample
UID: 88ea51e0-5f49-11e9-bd0b-00163e30eb10
Spec:
Jobs:
Name: scale-down
Schedule: 30 */1 * * * *
Target Size: 1
Name: scale-up
Schedule: 0 */1 * * * *
Target Size: 3
Scale Target Ref:
API Version: apps/v1beta2
Kind: Deployment
Name: nginx-deployment-basic
Status:
Conditions:
Job Id: 84818af0-3293-43e8-8ba6-6fd3ad2c35a4
Last Probe Time: 2019-04-15T06:42:30Z
Message: cron hpa job scale-down executed successfully
Name: scale-down
Schedule: 30 */1 * * * *
State: Succeed
Job Id: f8579f11-b129-4e72-b35f-c0bdd32583b3
Last Probe Time: 2019-04-15T06:42:20Z
Message:
Name: scale-up
Schedule: 0 */1 * * * *
State: Submitted
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Succeed 5s cron-horizontal-pod-autoscaler cron hpa job scale-down executed successfully
🍻Cheers! It works.
The following is an example of a CronHorizontalPodAutoscaler
.
apiVersion: autoscaling.alibabacloud.com/v1beta1
kind: CronHorizontalPodAutoscaler
metadata:
labels:
controller-tools.k8s.io: "1.0"
name: cronhpa-sample
namespace: default
spec:
scaleTargetRef:
apiVersion: apps/v1beta2
kind: Deployment
name: nginx-deployment-basic
jobs:
- name: "scale-down"
schedule: "30 */1 * * * *"
targetSize: 1
- name: "scale-up"
schedule: "0 */1 * * * *"
targetSize: 3
The scaleTargetRef
is the field to specify workload to scale. If the workload supports scale
subresource(such as Deployment
and StatefulSet
), CronHorizontalPodAutoscaler
should work well. CronHorizontalPodAutoscaler
support multi cronhpa job in one spec.
The cronhpa job spec need three fields:
-
name
name
should be unique in one cronhpa spec. You can distinguish different job execution status by job name. -
schedule
The scheme ofschedule
is similar withcrontab
.kubernetes-cronhpa-controller
use an enhanced cron golang lib (go-cron) which support more expressive rules.The cron expression format is as described below:
Field name | Mandatory? | Allowed values | Allowed special characters ---------- | ---------- | -------------- | -------------------------- Seconds | Yes | 0-59 | * / , - Minutes | Yes | 0-59 | * / , - Hours | Yes | 0-23 | * / , - Day of month | Yes | 1-31 | * / , - ? Month | Yes | 1-12 or JAN-DEC | * / , - Day of week | Yes | 0-6 or SUN-SAT | * / , - ?
The asterisk indicates that the cron expression will match for all values of the field; e.g., using an asterisk in the 5th field (month) would indicate every month.
Slashes are used to describe increments of ranges. For example 3-59/15 in the 1st field (minutes) would indicate the 3rd minute of the hour and every 15 minutes thereafter. The form "*/..." is equivalent to the form "first-last/...", that is, an increment over the largest possible range of the field. The form "N/..." is accepted as meaning "N-MAX/...", that is, starting at N, use the increment until the end of that specific range. It does not wrap around.
Commas are used to separate items of a list. For example, using "MON,WED,FRI" in the 5th field (day of week) would mean Mondays, Wednesdays and Fridays.
Hyphens are used to define ranges. For example, 9-17 would indicate every hour between 9am and 5pm inclusive.
Question mark may be used instead of '*' for leaving either day-of-month or day-of-week blank.
more schedule scheme please check this doc.
-
targetSize
TargetSize
is the size you desired to scale when the scheduled time arrive.
- Cloud
kubernetes-cronhpa-controller
and HPA work together?
Yes and no is the answer.kubernetes-cronhpa-controller
can work together with hpa. But if the desired replicas is independent. So when the HPA min replicas reachedkubernetes-cronhpa-controller
will ignore the replicas and scale down and later the HPA controller will scale it up.
Please check CONTRIBUTING.md
This software is released under the Apache 2.0 license.