autoscaling

const (
	// The internal autoscaling group name. This is used for CRDs.
	InternalGroupName = "autoscaling.internal.knative.dev"

	// The public autoscaling group name. This is used for annotations, labels, etc.
	GroupName = "autoscaling.knative.dev"

	// ClassAnnotationKey is the annotation for the explicit class of autoscaler
	// that a particular resource has opted into. For example,
	//   autoscaling.knative.dev/class: foo
	// This uses a different domain because unlike the resource, it is user-facing.
	ClassAnnotationKey = GroupName + "/class"
	// KPA is Knative Horizontal Pod Autoscaler
	KPA = "kpa.autoscaling.knative.dev"
	// HPA is Kubernetes Horizontal Pod Autoscaler
	HPA = "hpa.autoscaling.knative.dev"

	// MinScaleAnnotationKey is the annotation to specify the minimum number of Pods
	// the PodAutoscaler should provision. For example,
	//   autoscaling.knative.dev/minScale: "1"
	MinScaleAnnotationKey = GroupName + "/minScale"
	// MaxScaleAnnotationKey is the annotation to specify the maximum number of Pods
	// the PodAutoscaler should provision. For example,
	//   autoscaling.knative.dev/maxScale: "10"
	MaxScaleAnnotationKey = GroupName + "/maxScale"

	// MetricAnnotationKey is the annotation to specify what metric the PodAutoscaler
	// should be scaled on. For example,
	//   autoscaling.knative.dev/metric: cpu
	MetricAnnotationKey = GroupName + "/metric"
	// Concurrency is the number of requests in-flight at any given time.
	Concurrency = "concurrency"
	// CPU is the amount of the requested cpu actually being consumed by the Pod.
	CPU = "cpu"
	// RPS is the requests per second reaching the Pod.
	RPS = "rps"

	// TargetAnnotationKey is the annotation to specify what metric value the
	// PodAutoscaler should attempt to maintain. For example,
	//   autoscaling.knative.dev/metric: cpu
	//   autoscaling.knative.dev/target: "75"   # target 75% cpu utilization
	TargetAnnotationKey = GroupName + "/target"
	// TargetMin is the minimum allowable target.
	// This can be less than 1 due to the fact that with small container
	// concurrencies and small target utilization values this can get
	// below 1.
	TargetMin = 0.01

	// WindowAnnotationKey is the annotation to specify the time
	// interval over which to calculate the average metric.  Larger
	// values result in more smoothing. For example,
	//   autoscaling.knative.dev/metric: concurrency
	//   autoscaling.knative.dev/window: "2m"
	// Only the kpa.autoscaling.knative.dev class autoscaler supports
	// the window annotation.
	WindowAnnotationKey = GroupName + "/window"
	// WindowMin is the minimum allowable stable autoscaling
	// window. KPA-class autoscalers calculate the desired replica
	// count every 2 seconds (tick-interval in config-autoscaler) so
	// the closer the window gets to that value, the more likely data
	// points will be missed entirely by the panic window which is
	// smaller than the stable window. Anything less than 6 seconds
	// isn't going to work well.
	WindowMin = 6 * time.Second
	// WindowMax is the maximum permitted stable autoscaling window.
	// This keeps the event horizon to a reasonable enough limit.
	WindowMax = 1 * time.Hour

	// TargetUtilizationPercentageKey is the annotation which specifies the
	// desired target resource utilization for the revision.
	// TargetUtilization is a percentage in the 1 <= TU <= 100 range.
	// This annotation takes precedence over the config map value.
	TargetUtilizationPercentageKey = GroupName + "/targetUtilizationPercentage"

	// TargetBurstCapacityKey specifies the desired burst capacity for the
	// revision. Possible values are:
	// -1 -- infinite;
	//  0 -- no TBC;
	// >0 -- actual TBC.
	// <0 && != -1 -- an error.
	TargetBurstCapacityKey = GroupName + "/targetBurstCapacity"

	// PanicWindowPercentageAnnotationKey is the annotation to
	// specify the time interval over which to calculate the average
	// metric during a spike. Where a spike is defined as the metric
	// reaching panic level within the panic window (e.g. panic
	// mode). Lower values make panic mode more sensitive. Note:
	// Panic threshold can be overridden with the
	// PanicThresholdPercentageAnnotationKey. For example,
	//   autoscaling.knative.dev/panicWindowPercentage: "5.0"
	//   autoscaling.knative.dev/panicThresholdPercentage: "150.0"
	// Only the kpa.autoscaling.knative.dev class autoscaler supports
	// the panicWindowPercentage annotation.
	// Panic window is specified as a percentage to maintain the
	// autoscaler's algorithm behavior when only the stable window is
	// specified. The panic window will change along with the stable
	// window at the default percentage.
	PanicWindowPercentageAnnotationKey = GroupName + "/panicWindowPercentage"
	// PanicWindowPercentageMin is the minimum allowable panic window
	// percentage. The autoscaler calculates desired replicas every 2
	// seconds (tick-interval in config-autoscaler), so a panic
	// window less than 2 seconds will be missing data points. One
	// percent is a very small ratio and would require a stable
	// window of at least 3.4 minutes. Anything less doesn't make
	// sense.
	PanicWindowPercentageMin = 1.0
	// PanicWindowPercentageMax is the maximum allowable panic window
	// percentage. The KPA autoscaler's panic feature allows the
	// autoscaler to be more responsive over a smaller time scale
	// when necessary. So the panic window cannot be larger than the
	// stable window.
	PanicWindowPercentageMax = 100.0

	// PanicThresholdPercentageAnnotationKey is the annotation to specify
	// the level at what level panic mode will engage when reached within
	// in the panic window. The level is defined as a percentage of
	// the metric target. Lower values make panic mode more
	// sensitive. For example,
	//   autoscaling.knative.dev/panicWindowPercentage: "5.0"
	//   autoscaling.knative.dev/panicThresholdPercentage: "150.0"
	// Only the kpa.autoscaling.knative.dev class autoscaler supports
	// the panicThresholdPercentage annotation
	PanicThresholdPercentageAnnotationKey = GroupName + "/panicThresholdPercentage"
	// PanicThresholdPercentageMin is the minimum allowable panic
	// threshold percentage. The KPA autoscaler's panic feature
	// allows the autoscaler to be more responsive over a smaller
	// time scale when necessary. To prevent flapping, during panic
	// mode the autoscaler never decreases the number of replicas. If
	// the panic threshold was as small as the stable target, the
	// autoscaler would always be panicking and the autoscaler would
	// never scale down. One hundred and ten percent is about the
	// smallest useful value.
	PanicThresholdPercentageMin = 110.0

	// PanicThresholdPercentageMax is the counterpart to the PanicThresholdPercentageMin
	// but bounding from above.
	PanicThresholdPercentageMax = 1000.0

	// KPALabelKey is the label key attached to a K8s Service to hint to the KPA
	// which services/endpoints should trigger reconciles.
	KPALabelKey = GroupName + "/kpa"

	// PreferForScaleDownLabel is the label key set on a pod which is selected
	// by the autoscaler as a candidate for removal. Once the label is set to "true", it
	// signals the QueueProxy to fail readiness on the pod
	PreferForScaleDownLabelKey = GroupName + "/prefer-for-scale-down"
)