Autoscaling concepts

    Knative Serving supports the implementation of Knative Pod Autoscaler (KPA) and Kubernetes’ Horizontal Pod Autoscaler (HPA). The features and limitations of each of these Autoscalers are listed below.

    IMPORTANT: If you want to use Kubernetes Horizontal Pod Autoscaler (HPA), you must install it after you install Knative Serving.

    • Part of the Knative Serving core and enabled by default once Knative Serving is installed.
    • Supports scale to zero functionality.
    • Does not support CPU-based autoscaling.

    Horizontal Pod Autoscaler (HPA)

    The type of Autoscaler implementation (KPA or HPA) can be configured by using the annotation.

    • Global settings key: pod-autoscaler-class
    • Per-revision annotation key: autoscaling.knative.dev/class
    • Possible values: or "hpa.autoscaling.knative.dev"
    • Default: "kpa.autoscaling.knative.dev"

    Configuring for autoscaling in Knative can be set using either global or per-revision settings.

    1. If per-revision settings are specified, these will override the global settings when both types of settings exist.

    Global settings

    Global settings for autoscaling are configured using the ConfigMap. If you installed Knative Serving using the Operator, you can set global configuration settings in the spec.config.autoscaler ConfigMap, located in the KnativeServing custom resource (CR).

    Example of the default autoscaling ConfigMap

    Per-revision settings for autoscaling are configured by adding annotations to a revision.

    Example

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