cronhpatrait

README

CronHPATrait

Use Cron expressions to periodically scale your workload.

Supported workloads:

• ContainerizedWorkload
• Deployment
• StatefulSet

Prerequisites

1. Please follow common prerequisites to install OAM Controllers.
2. Please install kubernetes-cronhpa-controller.

Getting started

• Get the CronHPATrait project to your GOPATH

git clone https://github.com/oam-dev/catalog.git

• Install CRD to your Kubernetes cluster

cd catalog/traits/cronhpatrait/

make install

• Run the CronHPATrait controller

go run main.go

ContainerizedWorkload

• Apply the sample ContainerizedWorkload

kubectl apply -f config/samples/containerized

# ./config/samples/contaierized/sample_application_config.yaml

  ...
      traits:
        - trait:
            apiVersion: core.oam.dev/v1alpha2
            kind: CronHPATrait
            metadata:
              name: example-cronhpa-trait
            spec:
              jobs:
                - name: "scale-down"
                  schedule: "30 */1 * * * *"
                  targetSize: 1
                - name: "scale-up"
                  schedule: "0 */1 * * * *"
                  targetSize: 3

• Verify CronHPATrait you should see a deployment created by ContainerizedWorkload

kubectl get deployment
NAME                                    READY   UP-TO-DATE   AVAILABLE   AGE
example-appconfig-workload-deployment   1/1     1            1           3s

• And a CronHPA automatically created by CronHPATrait controller

kubectl get cronhpa
NAME                    AGE
example-cronhpa-trait   35s

• You should see a CronHPA and it's spec looking like below

kubectl get cronhpa
NAME                    AGE
example-cronhpa-trait   2m18s

kubectl describe cronhpa
...
  Exclude Dates:  <nil>
  Jobs:
    Name:         scale-down
    Run Once:     false
    Schedule:     30 */1 * * * *
    Target Size:  1
    Name:         scale-up
    Run Once:     false
    Schedule:     0 */1 * * * *
    Target Size:  3
...

• Verrify CronHPA works

# kubectl get deployment -w

NAME                                    READY   UP-TO-DATE   AVAILABLE   AGE
example-appconfig-workload-deployment   1/1     1            1           2m
example-appconfig-workload-deployment   1/3     1            1           2m
example-appconfig-workload-deployment   1/3     1            1           2m
example-appconfig-workload-deployment   1/3     1            1           2m
example-appconfig-workload-deployment   1/3     3            1           2m
example-appconfig-workload-deployment   2/3     3            2           2m
example-appconfig-workload-deployment   2/3     3            2           2m
example-appconfig-workload-deployment   3/3     3            3           2m
example-appconfig-workload-deployment   3/1     3            3           2m
example-appconfig-workload-deployment   3/1     3            3           2m
example-appconfig-workload-deployment   3/1     3            3           2m
example-appconfig-workload-deployment   1/1     1            1           2m

K8s Deployment

• Apply the sample Deployment

kubectl apply -f config/samples/deployment

# ./config/samples/deployment/sample_workload_definition.yaml
  
apiVersion: core.oam.dev/v1alpha2
kind: WorkloadDefinition
metadata:
  name: deployments.apps
spec:
  definitionRef:
    name: deployments.apps

# ./config/samples/deployment/sample_application_config.yaml

  ...
      traits:
        - trait:
            apiVersion: core.oam.dev/v1alpha2
            kind: CronHPATrait
            metadata:
              name: example-cronhpa-trait
            spec:
              jobs:
                - name: "scale-down"
                  schedule: "30 */1 * * * *"
                  targetSize: 1
                  runOnce: true
                - name: "scale-up"
                  schedule: "0 */1 * * * *"
                  targetSize: 3
                  runOnce: true
              excludeDates:
                # exclude November 15th
                - "* * * 15 11 *"
                # exclude every Friday
                - "* * * * * 5"

• Verify CronHPATrait you should see a deployment looking like below

kubectl get deployment
NAME   READY   UP-TO-DATE   AVAILABLE   AGE
web    1/1     1            1           15s

• And a CronHPA automatically created by CronHPATrait controller

kubectl get cronhpa
NAME                    AGE
example-cronhpa-trait   28s

• You should see a CronHPA and it's spec looking like below

kubectl get cronhpa
NAME                    AGE
example-cronhpa-trait   28s

kubectl describe cronhpa
...
  Exclude Dates:
    * * * 15 11 *
    * * * * * 5
  Jobs:
    Name:         scale-down
    Run Once:     true
    Schedule:     30 */1 * * * *
    Target Size:  1
    Name:         scale-up
    Run Once:     true
    Schedule:     0 */1 * * * *
    Target Size:  3
  Scale Target Ref:
    API Version:  apps/v1
    Kind:         Deployment
    Name:         web
...

• Verrify CronHPA works and the result is same as ContainerizedWorkload

K8s StatefulSet

• Apply the sample StatefulSet

kubectl apply -f config/samples/statefulset

# ./config/samples/statefulset/sample_workload_definition.yaml
  
apiVersion: core.oam.dev/v1alpha2
kind: WorkloadDefinition
metadata:
  name: statefulsets.apps
spec:
  definitionRef:
    name: statefulsets.apps

# ./config/samples/statefulset/sample_application_config.yaml

  ...
      traits:
        - trait:
            apiVersion: core.oam.dev/v1alpha2
            kind: CronHPATrait
            metadata:
              name: example-cronhpa-trait
            spec:
              jobs:
                - name: "scale-down"
                  schedule: "30 */1 * * * *"
                  targetSize: 1
                - name: "scale-up"
                  schedule: "0 */1 * * * *"
                  targetSize: 3

• Verify CronHPATrait you should see a statefulset looking like below

kubectl get statefulset
NAME   READY   AGE
web    1/1     22s

• And a CronHPA automatically created by CronHPATrait controller

kubectl get cronhpa
NAME                    AGE
example-cronhpa-trait   62s

• You should see a CronHPA and it's spec looking like below

kubectl get cronhpa
NAME                    AGE
example-cronhpa-trait   62s

kubectl describe cronhpa
...
  Exclude Dates:  <nil>
  Jobs:
    Name:         scale-down
    Run Once:     false
    Schedule:     30 */1 * * * *
    Target Size:  1
    Name:         scale-up
    Run Once:     false
    Schedule:     0 */1 * * * *
    Target Size:  3
...

• Verrify CronHPA works and the result is same as ContainerizedWorkload

How it work?

Essentially, the CronHPATrait controller will generate CronHPA based on the workload spec.

In detail:

• If the workload type is ContainerizedWorkload which has two child resources (Deployment and Service), CronHPATrait can help to create corresponding CronHPA.
• If the workload type is K8S native resources (StatefulSet or Deployment), CronHPATrait can help to create a CronHPA.