You can use Horizontal Pod Autoscaler (HPA) in Knative to automatically scale the number of resources. You can set the threshold of the CPU metric for a Knative service. This ensures that resources are automatically scaled to handle heavy workloads. This topic describes how to use HPA in Knative.

Prerequisites

Deploy Knative

Procedure

  1. Create the ksvc-hpa.yaml file.

    Configure an HPA scaling policy for a Knative service. The following code block is an example. 

    apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: helloworld-go-hpa
spec:
  template:
    metadata:
      labels:
        app: helloworld-go-hpa
      annotations:
        autoscaling.knative.dev/class: "hpa.autoscaling.knative.dev"
        autoscaling.knative.dev/metric: "cpu"
        autoscaling.knative.dev/target: "75"
        autoscaling.knative.dev/minScale: "1"
        autoscaling.knative.dev/maxScale: "10"
    spec:
      containers:
        - image: registry.cn-hangzhou.aliyuncs.com/knative-samples/helloworld-go:160e4dc8
          resources:
            requests:
              cpu: '200m'
    • autoscaling.knative.dev/class: "hpa.autoscaling.knative.dev" specifies the HPA plug-in.
    • autoscaling.knative.dev/metric specifies the CPU metric.
    • autoscaling.knative.dev/target specifies the threshold of the CPU metric.
    • autoscaling.knative.dev/minScale: "1" specifies the minimum number of instances in the scaling policy.
    • autoscaling.knative.dev/maxScale: "10" specifies the maximum number of instances in the scaling policy.
  2. Apply the scaling policy.
    kubectl apply -f ksvc-hpa.yaml

Result

After HPA is enabled for the Knative service, the number of instances is automatically scaled, as shown in the following figure.Instance scaling