Overview

Add-on description

HorizontalPodCronscaler (HPC) is an add-on to modify the number of replicas of K8s workload. Used in conjunction with HPC CRD resources, it can support scheduled actions in seconds.

Add-on features

• Configures "Pod Range" (when the associated object is HPA) or "Desired Number of Pods" (when the associated object is Deployment or StatefulSet).
• Sets an “Exceptional Time”. The smallest granularity of the setting is Day. Multiple exceptional times are allowed.
• Specifies whether the scheduled task runs only once.

Kubernetes objects deployed in a cluster

Deploying HPC Add-on in a cluster will deploy the following Kubernetes objects in the cluster:

Limits

Environment requirements

Note：

If you create a cluster of version 1.12.4 or later, you can use the cluster directly without any parameter changes.

• This add-on is supported only by Kubernetes 1.12 or later versions.
• The launch parameters of kube-apiserver must be set as follows: --feature-gates=CustomResourceSubresources=true.

Node Requirements

• The HPC add-on follows the timezone of the associated server. Please make sure that the /etc/localtime file exists in the node.
• By default, two HPC Pods are installed on different nodes. Therefore at least two nodes are required.

Requirement on resource to be controlled

When you create an HPC resource, please make sure that the workload (K8s resource) to be controlled exists in the cluster.

Directions

Installing HPC

1. Log in to the TKE console and select Cluster in the left sidebar.
2. On the “Cluster Management page, click the ID of the target cluster to go to the cluster details page.
3. In the left sidebar, click Add-on Management to go to the Add-on List page.
4. On the "Add-on List" page, click Create, On the "Create Add-on" page that appears, select HPC.
5. Click Done.

Examples

Creating a scheduled task resource that associated with Deployment

The example is as follows:

apiVersion: autoscaling.cloud.tencent.com/v1
kind: HorizontalPodCronscaler
metadata:
  name: hpc-deployment
  namespace: default 
spec:
  scaleTarget:
    apiVersion: apps/v1
    kind: Deployment
    name: nginx-deployment
    namespace: default 
  crons:
- name: "scale-down"
  excludeDates:
    - "* * * 15 11 *"
    - "* * * * * 5"
  schedule: "30 */1 * * * *"
  targetSize: 1
- name: "scale-up"
  excludeDates:
    - "* * * 15 11 *"
    - "* * * * * 5"
  schedule: "0 */1 * * * *"
  targetSize: 3

Creating a scheduled task resource that associated with StatefulSet

The example is as follows:

apiVersion: autoscaling.cloud.tencent.com/v1
kind: HorizontalPodCronscaler
metadata:
  name: hpc-statefulset
  namespace: default
spec:
  scaleTarget:
    apiVersion: apps/v1
    kind: Statefulset
    name: nginx-statefulset
    namespace: default
  crons:
  - name: "scale-down"
    excludeDates:
      - "* * * 15 11 *"
    schedule: "0 */2 * * * *"
    targetSize: 1
  - name: "scale-up"
    excludeDates:
      - "* * * 15 11 *"
    schedule: "30 */2 * * * *"
    targetSize: 4

Creating a scheduled task resource that associated with HPA

The example is as follows:

apiVersion: autoscaling.cloud.tencent.com/v1
kind: HorizontalPodCronscaler
metadata:
  labels:
    controller-tools.k8s.io: "1.0"
  name: hpc-hpa
spec:
  scaleTarget:
    apiVersion: autoscaling/v1
    kind: HorizontalPodAutoscaler
    name:  nginx-hpa
    namespace: default
  crons:
  - name: "scale-up"
    schedule: "30 */1 * * * *"
    minSize: 2
    maxSize: 6
  - name: "scale-down"
    schedule: "0 */1 * * * *"
    minSize: 1
    maxSize: 5

Scheduled duration settings