agones.dev/agones@v1.53.0/pkg/apis/autoscaling/v1/fleetautoscaler.go

// Copyright 2019 Google LLC All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package v1

import (
	"crypto/x509"
	"errors"
	"fmt"
	"net/url"
	"strings"
	"time"

	agonesv1 "agones.dev/agones/pkg/apis/agones/v1"
	"agones.dev/agones/pkg/util/runtime"
	"github.com/robfig/cron/v3"
	admregv1 "k8s.io/api/admissionregistration/v1"
	apimachineryvalidation "k8s.io/apimachinery/pkg/api/validation"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/intstr"
	"k8s.io/apimachinery/pkg/util/validation/field"
)

// +genclient
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// FleetAutoscaler is the data structure for a FleetAutoscaler resource
type FleetAutoscaler struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`

	Spec   FleetAutoscalerSpec   `json:"spec"`
	Status FleetAutoscalerStatus `json:"status"`
}

// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

// FleetAutoscalerList is a list of Fleet Scaler resources
type FleetAutoscalerList struct {
	metav1.TypeMeta `json:",inline"`
	metav1.ListMeta `json:"metadata,omitempty"`

	Items []FleetAutoscaler `json:"items"`
}

// FleetAutoscalerSpec is the spec for a Fleet Scaler
type FleetAutoscalerSpec struct {
	FleetName string `json:"fleetName"`

	// Autoscaling policy
	Policy FleetAutoscalerPolicy `json:"policy"`
	// Sync defines when FleetAutoscalers runs autoscaling
	// +optional
	Sync *FleetAutoscalerSync `json:"sync,omitempty"`
}

// FleetAutoscalerPolicy describes how to scale a fleet
type FleetAutoscalerPolicy struct {
	// Type of autoscaling policy.
	Type FleetAutoscalerPolicyType `json:"type"`

	// Buffer policy config params. Present only if FleetAutoscalerPolicyType = Buffer.
	// +optional
	Buffer *BufferPolicy `json:"buffer,omitempty"`
	// Webhook policy config params. Present only if FleetAutoscalerPolicyType = Webhook.
	// +optional
	Webhook *URLConfiguration `json:"webhook,omitempty"`
	// [Stage:Beta]
	// [FeatureFlag:CountsAndLists]
	// Counter policy config params. Present only if FleetAutoscalerPolicyType = Counter.
	// +optional
	Counter *CounterPolicy `json:"counter,omitempty"`
	// [Stage:Beta]
	// [FeatureFlag:CountsAndLists]
	// List policy config params. Present only if FleetAutoscalerPolicyType = List.
	// +optional
	List *ListPolicy `json:"list,omitempty"`
	// [Stage:Beta]
	// [FeatureFlag:ScheduledAutoscaler]
	// Schedule policy config params. Present only if FleetAutoscalerPolicyType = Schedule.
	// +optional
	Schedule *SchedulePolicy `json:"schedule,omitempty"`
	// [Stage:Beta]
	// [FeatureFlag:ScheduledAutoscaler]
	// Chain policy config params. Present only if FleetAutoscalerPolicyType = Chain.
	// +optional
	Chain ChainPolicy `json:"chain,omitempty"`
	// Wasm policy config params. Present only if FleetAutoscalerPolicyType = Wasm.
	// +optional
	Wasm *WasmPolicy `json:"wasm,omitempty"`
}

// FleetAutoscalerPolicyType is the policy for autoscaling
// for a given Fleet
type FleetAutoscalerPolicyType string

// FleetAutoscalerSync describes when to sync a fleet
type FleetAutoscalerSync struct {
	// Type of autoscaling sync.
	Type FleetAutoscalerSyncType `json:"type"`

	// FixedInterval config params. Present only if FleetAutoscalerSyncType = FixedInterval.
	// +optional
	FixedInterval FixedIntervalSync `json:"fixedInterval"`
}

// FleetAutoscalerSyncType is the sync strategy for a given Fleet
type FleetAutoscalerSyncType string

const (
	// BufferPolicyType FleetAutoscalerPolicyType is a simple buffering strategy for Ready
	// GameServers
	BufferPolicyType FleetAutoscalerPolicyType = "Buffer"
	// WebhookPolicyType is a simple webhook strategy used for horizontal fleet scaling
	// GameServers
	WebhookPolicyType FleetAutoscalerPolicyType = "Webhook"
	// [Stage:Beta]
	// [FeatureFlag:CountsAndLists]
	// CounterPolicyType is for Counter based fleet autoscaling
	// nolint:revive // Linter contains comment doesn't start with CounterPolicyType
	CounterPolicyType FleetAutoscalerPolicyType = "Counter"
	// [Stage:Beta]
	// [FeatureFlag:CountsAndLists]
	// ListPolicyType is for List based fleet autoscaling
	// nolint:revive // Linter contains comment doesn't start with ListPolicyType
	ListPolicyType FleetAutoscalerPolicyType = "List"
	// [Stage:Beta]
	// [FeatureFlag:ScheduledAutoscaler]
	// SchedulePolicyType is for Schedule based fleet autoscaling
	// nolint:revive // Linter contains comment doesn't start with SchedulePolicyType
	SchedulePolicyType FleetAutoscalerPolicyType = "Schedule"
	// [Stage:Beta]
	// [FeatureFlag:ScheduledAutoscaler]
	// ChainPolicyType is for Chain based fleet autoscaling
	// nolint:revive // Linter contains comment doesn't start with ChainPolicyType
	ChainPolicyType FleetAutoscalerPolicyType = "Chain"
	// WasmPolicyType is for WebAssembly based fleet autoscaling
	// [Stage:Alpha]
	// [FeatureFlag:WasmAutoscaler]
	WasmPolicyType FleetAutoscalerPolicyType = "Wasm"
	// FixedIntervalSyncType is a simple fixed interval based strategy for trigger autoscaling
	FixedIntervalSyncType FleetAutoscalerSyncType = "FixedInterval"

	defaultIntervalSyncSeconds int32 = 30
)

// BufferPolicy controls the desired behavior of the buffer policy.
type BufferPolicy struct {
	// MaxReplicas is the maximum amount of replicas that the fleet may have.
	// It must be bigger than both MinReplicas and BufferSize
	MaxReplicas int32 `json:"maxReplicas"`

	// MinReplicas is the minimum amount of replicas that the fleet must have
	// If zero, it is ignored.
	// If non zero, it must be smaller than MaxReplicas and bigger than BufferSize
	MinReplicas int32 `json:"minReplicas"`

	// BufferSize defines how many replicas the autoscaler tries to have ready all the time
	// Value can be an absolute number (ex: 5) or a percentage of desired gs instances (ex: 15%)
	// Absolute number is calculated from percentage by rounding up.
	// Example: when this is set to 20%, the autoscaler will make sure that 20%
	//   of the fleet's game server replicas are ready. When this is set to 20,
	//   the autoscaler will make sure that there are 20 available game servers
	// Must be bigger than 0
	// Note: by "ready" we understand in this case "non-allocated"; this is done to ensure robustness
	//       and computation stability in different edge case (fleet just created, not enough
	//       capacity in the cluster etc)
	BufferSize intstr.IntOrString `json:"bufferSize"`
}

// URLConfiguration is a generic configuration for any integration with an external URL or
// cluster provided service. For example, it can be used to configure a webhook or Wasm module
type URLConfiguration admregv1.WebhookClientConfig

// CounterPolicy controls the desired behavior of the Counter autoscaler policy.
type CounterPolicy struct {
	// Key is the name of the Counter. Required field.
	Key string `json:"key"`

	// MaxCapacity is the maximum aggregate Counter total capacity across the fleet.
	// MaxCapacity must be bigger than both MinCapacity and BufferSize. Required field.
	MaxCapacity int64 `json:"maxCapacity"`

	// MinCapacity is the minimum aggregate Counter total capacity across the fleet.
	// If zero, MinCapacity is ignored.
	// If non zero, MinCapacity must be smaller than MaxCapacity and bigger than BufferSize.
	MinCapacity int64 `json:"minCapacity"`

	// BufferSize is the size of a buffer of counted items that are available in the Fleet (available
	// capacity). Value can be an absolute number (ex: 5) or a percentage of desired gs instances
	// (ex: 5%). An absolute number is calculated from percentage by rounding up.
	// Must be bigger than 0. Required field.
	BufferSize intstr.IntOrString `json:"bufferSize"`
}

// ListPolicy controls the desired behavior of the List autoscaler policy.
type ListPolicy struct {
	// Key is the name of the List. Required field.
	Key string `json:"key"`

	// MaxCapacity is the maximum aggregate List total capacity across the fleet.
	// MaxCapacity must be bigger than both MinCapacity and BufferSize. Required field.
	MaxCapacity int64 `json:"maxCapacity"`

	// MinCapacity is the minimum aggregate List total capacity across the fleet.
	// If zero, it is ignored.
	// If non zero, it must be smaller than MaxCapacity and bigger than BufferSize.
	MinCapacity int64 `json:"minCapacity"`

	// BufferSize is the size of a buffer based on the List capacity that is available over the
	// current aggregate List length in the Fleet (available capacity). It can be specified either
	// as an absolute value (i.e. 5) or percentage format (i.e. 5%).
	// Must be bigger than 0. Required field.
	BufferSize intstr.IntOrString `json:"bufferSize"`
}

// Between defines the time period that the policy is eligible to be applied.
type Between struct {
	// Start is the datetime that the policy is eligible to be applied.
	// This field must conform to RFC3339 format. If this field not set or is in the past, the policy is eligible to be applied
	// as soon as the fleet autoscaler is running.
	Start metav1.Time `json:"start"`

	// End is the datetime that the policy is no longer eligible to be applied.
	// This field must conform to RFC3339 format. If not set, the policy is always eligible to be applied, after the start time above.
	End metav1.Time `json:"end"`
}

// ActivePeriod defines the time period that the policy is applied.
type ActivePeriod struct {
	// Timezone to be used for the startCron field. If not set, startCron is defaulted to the UTC timezone.
	Timezone string `json:"timezone"`

	// StartCron defines when the policy should be applied.
	// If not set, the policy is always to be applied within the start and end time.
	// This field must conform to UNIX cron syntax.
	StartCron string `json:"startCron"`

	// Duration is the length of time that the policy is applied.
	// If not set, the duration is indefinite.
	// A duration string is a possibly signed sequence of decimal numbers,
	// (e.g. "300ms", "-1.5h" or "2h45m").
	// The representation limits the largest representable duration to approximately 290 years.
	// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
	Duration string `json:"duration"`
}

// SchedulePolicy controls the desired behavior of the Schedule autoscaler policy.
type SchedulePolicy struct {
	// Between defines the time period that the policy is eligible to be applied.
	Between Between `json:"between"`

	// ActivePeriod defines the time period that the policy is applied.
	ActivePeriod ActivePeriod `json:"activePeriod"`

	// Policy is the name of the policy to be applied. Required field.
	Policy FleetAutoscalerPolicy `json:"policy"`
}

// ChainEntry defines a single entry in the ChainPolicy.
type ChainEntry struct {
	// ID is the unique identifier for a ChainEntry. If not set the identifier will be set to the index of chain entry.
	ID string `json:"id"`

	// Policy is the name of the policy to be applied. Required field.
	FleetAutoscalerPolicy `json:",inline"`
}

// ChainPolicy controls the desired behavior of the Chain autoscaler policy.
type ChainPolicy []ChainEntry

// WasmFrom defines the source of the Wasm module
type WasmFrom struct {
	// URL is the URL of the Wasm module to use for autoscaling.
	URL *URLConfiguration `json:"url"`
}

// WasmPolicy controls the desired behavior of the Wasm policy.
// It contains the configuration for the WebAssembly module used for autoscaling.
type WasmPolicy struct {
	// Function is the exported function to call in the wasm module, defaults to 'scale'
	// +optional
	Function string `json:"function,omitempty"`
	// Config values to pass to the wasm program on startup
	// +optional
	Config map[string]string `json:"config,omitempty"`
	// WasmFrom defines the source of the Wasm module
	From WasmFrom `json:"from"`
	// Hash of the Wasm module, used to verify the integrity of the module
	// +optional
	Hash string `json:"hash,omitempty"`
}

// FixedIntervalSync controls the desired behavior of the fixed interval based sync.
type FixedIntervalSync struct {
	// Seconds defines how often we run fleet autoscaling in seconds
	Seconds int32 `json:"seconds"`
}

// FleetAutoscalerStatus defines the current status of a FleetAutoscaler
type FleetAutoscalerStatus struct {
	// CurrentReplicas is the current number of gameserver replicas
	// of the fleet managed by this autoscaler, as last seen by the autoscaler
	CurrentReplicas int32 `json:"currentReplicas"`

	// DesiredReplicas is the desired number of gameserver replicas
	// of the fleet managed by this autoscaler, as last calculated by the autoscaler
	DesiredReplicas int32 `json:"desiredReplicas"`

	// lastScaleTime is the last time the FleetAutoscaler scaled the attached fleet,
	// +optional
	LastScaleTime *metav1.Time `json:"lastScaleTime"`

	// AbleToScale indicates that we can access the target fleet
	AbleToScale bool `json:"ableToScale"`

	// ScalingLimited indicates that the calculated scale would be above or below the range
	// defined by MinReplicas and MaxReplicas, and has thus been capped.
	ScalingLimited bool `json:"scalingLimited"`

	// LastAppliedPolicy is the ID of the last applied policy in the ChainPolicy.
	// Used to track policy transitions for logging purposes.
	LastAppliedPolicy FleetAutoscalerPolicyType `json:"lastAppliedPolicy"`
}

// FleetAutoscaleRequest defines the request to webhook autoscaler endpoint
type FleetAutoscaleRequest struct {
	// UID is an identifier for the individual request/response. It allows us to distinguish instances of requests which are
	// otherwise identical (parallel requests, requests when earlier requests did not modify etc)
	// The UID is meant to track the round trip (request/response) between the Autoscaler and the WebHook, not the user request.
	// It is suitable for correlating log entries between the webhook and apiserver, for either auditing or debugging.
	UID types.UID `json:"uid"`
	// Name is the name of the Fleet being scaled
	Name string `json:"name"`
	// Namespace is the namespace associated with the request (if any).
	Namespace string `json:"namespace"`
	// The Fleet's status values
	Status agonesv1.FleetStatus `json:"status"`
	// Standard map labels; More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels.
	Labels map[string]string `json:"labels,omitempty"`
	// Standard map annotations; More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations.
	Annotations map[string]string `json:"annotations,omitempty"`
}

// FleetAutoscaleResponse defines the response of webhook autoscaler endpoint
type FleetAutoscaleResponse struct {
	// UID is an identifier for the individual request/response.
	// This should be copied over from the corresponding FleetAutoscaleRequest.
	UID types.UID `json:"uid"`
	// Set to false if no scaling should occur to the Fleet
	Scale bool `json:"scale"`
	// The targeted replica count
	Replicas int32 `json:"replicas"`
}

// FleetAutoscaleReview is passed to the webhook with a populated Request value,
// and then returned with a populated Response.
type FleetAutoscaleReview struct {
	Request  *FleetAutoscaleRequest  `json:"request"`
	Response *FleetAutoscaleResponse `json:"response"`
}

// Validate validates the FleetAutoscaler scaling settings
func (fas *FleetAutoscaler) Validate() field.ErrorList {
	allErrs := fas.Spec.Policy.ValidatePolicy(field.NewPath("spec", "policy"))

	if fas.Spec.Sync != nil {
		allErrs = append(allErrs, fas.Spec.Sync.FixedInterval.ValidateFixedIntervalSync(field.NewPath("spec", "sync", "fixedInterval"))...)
	}
	return allErrs
}

// ValidatePolicy validates a FleetAutoscalerPolicy's settings.
func (f *FleetAutoscalerPolicy) ValidatePolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	switch f.Type {
	case BufferPolicyType:
		allErrs = f.Buffer.ValidateBufferPolicy(fldPath.Child("buffer"))

	case WebhookPolicyType:
		allErrs = f.Webhook.ValidateURLConfiguration(fldPath.Child("webhook"))

	case CounterPolicyType:
		allErrs = f.Counter.ValidateCounterPolicy(fldPath.Child("counter"))

	case ListPolicyType:
		allErrs = f.List.ValidateListPolicy(fldPath.Child("list"))

	case SchedulePolicyType:
		allErrs = f.Schedule.ValidateSchedulePolicy(fldPath.Child("schedule"))

	case ChainPolicyType:
		allErrs = f.Chain.ValidateChainPolicy(fldPath.Child("chain"))

	case WasmPolicyType:
		allErrs = f.Wasm.ValidateWasmPolicy(fldPath.Child("wasm"))
	}
	return allErrs
}

// ValidateURLConfiguration validates the URLConfiguration settings to make sure either a URL is set or
// a Service is set, but not both. Also checks that the CABundle is valid if HTTPS is used.
func (w *URLConfiguration) ValidateURLConfiguration(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if w == nil {
		return append(allErrs, field.Required(fldPath, "webhook policy config params are missing"))
	}
	if w.Service == nil && w.URL == nil {
		allErrs = append(allErrs, field.Required(fldPath, "url should be provided"))
	}
	if w.Service != nil && w.URL != nil {
		allErrs = append(allErrs, field.Duplicate(fldPath.Child("url"), "service and url cannot be used simultaneously"))
	}
	if w.CABundle != nil {
		rootCAs := x509.NewCertPool()
		// Check that CABundle provided is correctly encoded certificate
		if ok := rootCAs.AppendCertsFromPEM(w.CABundle); !ok {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("caBundle"), w.CABundle, "CA Bundle is not valid"))
		}
	}
	if w.URL != nil {
		u, err := url.Parse(*w.URL)
		if err != nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("url"), *w.URL, "url is not valid"))
		} else if u.Scheme == "https" && w.CABundle == nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("caBundle"), w.CABundle, "CABundle should be provided if HTTPS webhook is used"))
		}

	}
	return allErrs
}

// ValidateBufferPolicy validates the FleetAutoscaler Buffer policy settings
func (b *BufferPolicy) ValidateBufferPolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if b == nil {
		return append(allErrs, field.Required(fldPath, "buffer policy config params are missing"))
	}
	if b.MinReplicas > b.MaxReplicas {
		allErrs = append(allErrs, field.Invalid(fldPath.Child("minReplicas"), b.MinReplicas, "minReplicas should be smaller than maxReplicas"))
	}
	if b.BufferSize.Type == intstr.Int {
		if b.BufferSize.IntValue() <= 0 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("bufferSize"), b.BufferSize.IntValue(), apimachineryvalidation.IsNegativeErrorMsg))
		}
		if b.MaxReplicas < int32(b.BufferSize.IntValue()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("maxReplicas"), b.MaxReplicas, "maxReplicas should be bigger than or equal to bufferSize"))
		}
		if b.MinReplicas != 0 && b.MinReplicas < int32(b.BufferSize.IntValue()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("minReplicas"), b.MinReplicas, "minReplicas should be bigger than or equal to bufferSize"))
		}
	} else {
		r, err := intstr.GetScaledValueFromIntOrPercent(&b.BufferSize, 100, true)
		if err != nil || r < 1 || r > 99 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("bufferSize"), b.BufferSize.String(), "bufferSize should be between 1% and 99%"))
		}
		// When there is no allocated gameservers in a fleet,
		// Fleetautoscaler would reduce size of a fleet to MinReplicas.
		// If we have 0 MinReplicas and 0 Allocated then Fleetautoscaler would set Ready Replicas to 0
		// and we will not be able to raise the number of GS in a Fleet above zero
		if b.MinReplicas < 1 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("minReplicas"), b.MinReplicas, apimachineryvalidation.IsNegativeErrorMsg))
		}
	}
	return allErrs
}

// ValidateCounterPolicy validates the FleetAutoscaler Counter policy settings.
// Does not validate if a Counter with name CounterPolicy.Key is present in the fleet.
// nolint:dupl  // Linter errors on lines are duplicate of ValidateListPolicy
func (c *CounterPolicy) ValidateCounterPolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if !runtime.FeatureEnabled(runtime.FeatureCountsAndLists) {
		return append(allErrs, field.Forbidden(fldPath, "feature CountsAndLists must be enabled"))
	}

	if c == nil {
		return append(allErrs, field.Required(fldPath, "counter policy config params are missing"))
	}

	if c.MinCapacity > c.MaxCapacity {
		allErrs = append(allErrs, field.Invalid(fldPath.Child("minCapacity"), c.MinCapacity, "minCapacity should be smaller than maxCapacity"))
	}

	if c.BufferSize.Type == intstr.Int {
		if c.BufferSize.IntValue() <= 0 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("bufferSize"), c.BufferSize.IntValue(), apimachineryvalidation.IsNegativeErrorMsg))
		}
		if c.MaxCapacity < int64(c.BufferSize.IntValue()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("maxCapacity"), c.MaxCapacity, "maxCapacity should be bigger than or equal to bufferSize"))
		}
		if c.MinCapacity != 0 && c.MinCapacity < int64(c.BufferSize.IntValue()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("minCapacity"), c.MinCapacity, "minCapacity should be bigger than or equal to bufferSize"))
		}
	} else {
		r, err := intstr.GetScaledValueFromIntOrPercent(&c.BufferSize, 100, true)
		if err != nil || r < 1 || r > 99 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("bufferSize"), c.BufferSize.String(), "bufferSize should be between 1% and 99%"))
		}
		// When bufferSize in percentage format is used, minCapacity should be more than 0.
		if c.MinCapacity < 1 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("minCapacity"), c.BufferSize.String(), " when bufferSize in percentage format is used, minCapacity should be more than 0"))
		}
	}

	return allErrs
}

// ValidateListPolicy validates the FleetAutoscaler List policy settings.
// Does not validate if a List with name ListPolicy.Key is present in the fleet.
// nolint:dupl  // Linter errors on lines are duplicate of ValidateCounterPolicy
func (l *ListPolicy) ValidateListPolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if !runtime.FeatureEnabled(runtime.FeatureCountsAndLists) {
		return append(allErrs, field.Forbidden(fldPath, "feature CountsAndLists must be enabled"))
	}
	if l == nil {
		return append(allErrs, field.Required(fldPath, "list policy config params are missing"))
	}
	if l.MinCapacity > l.MaxCapacity {
		allErrs = append(allErrs, field.Invalid(fldPath.Child("minCapacity"), l.MinCapacity, "minCapacity should be smaller than maxCapacity"))
	}
	if l.BufferSize.Type == intstr.Int {
		if l.BufferSize.IntValue() <= 0 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("bufferSize"), l.BufferSize.IntValue(), apimachineryvalidation.IsNegativeErrorMsg))
		}
		if l.MaxCapacity < int64(l.BufferSize.IntValue()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("maxCapacity"), l.MaxCapacity, "maxCapacity should be bigger than or equal to bufferSize"))
		}
		if l.MinCapacity != 0 && l.MinCapacity < int64(l.BufferSize.IntValue()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("minCapacity"), l.MinCapacity, "minCapacity should be bigger than or equal to bufferSize"))
		}
	} else {
		r, err := intstr.GetScaledValueFromIntOrPercent(&l.BufferSize, 100, true)
		if err != nil || r < 1 || r > 99 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("bufferSize"), l.BufferSize.String(), "bufferSize should be between 1% and 99%"))
		}
		// When bufferSize in percentage format is used, minCapacity should be more than 0.
		if l.MinCapacity < 1 {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("minCapacity"), l.BufferSize.String(), " when bufferSize in percentage format is used, minCapacity should be more than 0"))
		}
	}
	return allErrs
}

// ValidateSchedulePolicy validates the FleetAutoscaler Schedule policy settings.
func (s *SchedulePolicy) ValidateSchedulePolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if s == nil {
		return append(allErrs, field.Required(fldPath, "schedule policy config params are missing"))
	}
	if !runtime.FeatureEnabled(runtime.FeatureScheduledAutoscaler) {
		return append(allErrs, field.Forbidden(fldPath, "feature ScheduledAutoscaler must be enabled"))
	}
	if s.ActivePeriod.Timezone != "" {
		if _, err := time.LoadLocation(s.ActivePeriod.Timezone); err != nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("activePeriod").Child("timezone"), s.ActivePeriod.Timezone, fmt.Sprintf("Error parsing timezone: %s\n", err)))
		}
	}
	if !s.Between.End.IsZero() {
		startTime := s.Between.Start.Time
		endTime := s.Between.End.Time
		var endErr error
		if endTime.Before(time.Now()) {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("between").Child("end"), s.Between.End, "end time must be after the current time"))
			endErr = errors.New("end time before current time")
		}

		if !startTime.IsZero() && endErr == nil {
			if endTime.Before(startTime) {
				allErrs = append(allErrs, field.Invalid(fldPath.Child("between"), s.Between, "start time must be before end time"))
			}
		}
	}
	if s.ActivePeriod.StartCron != "" {
		// If startCron is not a valid cron expression, append an error
		if _, err := cron.ParseStandard(s.ActivePeriod.StartCron); err != nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("activePeriod").Child("startCron"), s.ActivePeriod.StartCron, fmt.Sprintf("invalid startCron: %s", err)))
		}
		// If the cron expression contains a CRON_TZ or TZ specification, append an error
		if strings.Contains(s.ActivePeriod.StartCron, "TZ") {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("activePeriod").Child("startCron"), s.ActivePeriod.StartCron, "CRON_TZ or TZ used in activePeriod is not supported, please use the .schedule.timezone field to specify a timezone"))
		}
	}
	if s.ActivePeriod.Duration != "" {
		if _, err := time.ParseDuration(s.ActivePeriod.Duration); err != nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("activePeriod").Child("duration"), s.ActivePeriod.StartCron, fmt.Sprintf("invalid duration: %s", err)))
		}
	}
	return allErrs
}

// ValidateChainPolicy validates the FleetAutoscaler Chain policy settings.
func (c *ChainPolicy) ValidateChainPolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if c == nil {
		return append(allErrs, field.Required(fldPath, "chain policy config params are missing"))
	}
	if !runtime.FeatureEnabled(runtime.FeatureScheduledAutoscaler) {
		return append(allErrs, field.Forbidden(fldPath, "feature ScheduledAutoscaler must be enabled"))
	}
	seenIDs := make(map[string]bool)
	for i, entry := range *c {

		// Ensure that all IDs are unique
		if seenIDs[entry.ID] {
			allErrs = append(allErrs, field.Invalid(fldPath, entry.ID, "id of chain entry must be unique"))
		} else {
			seenIDs[entry.ID] = true
		}
		// Ensure that chain entry has a policy
		hasValidPolicy := entry.Buffer != nil || entry.Webhook != nil || entry.Counter != nil || entry.List != nil || entry.Schedule != nil || entry.Wasm != nil
		if entry.Type == "" || !hasValidPolicy {
			allErrs = append(allErrs, field.Required(fldPath.Index(i), "valid policy is missing"))
		}
		// Validate the chain entry's policy
		allErrs = append(allErrs, entry.FleetAutoscalerPolicy.ValidatePolicy(fldPath.Index(i).Child("policy"))...)
	}
	return allErrs
}

// ValidateWasmPolicy validates the FleetAutoscaler Wasm policy settings
func (w *WasmPolicy) ValidateWasmPolicy(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if w == nil {
		return append(allErrs, field.Required(fldPath, "wasm policy config params are missing"))
	}

	if !runtime.FeatureEnabled(runtime.FeatureWasmAutoscaler) {
		return append(allErrs, field.Forbidden(fldPath, "feature WasmAutoscaler must be enabled"))
	}

	fldPath = fldPath.Child("from")
	if w.From.URL == nil {
		return append(allErrs, field.Required(fldPath, "wasm from configuration is missing"))
	}
	allErrs = w.From.URL.ValidateURLConfiguration(fldPath.Child("url"))

	return allErrs
}

// ValidateFixedIntervalSync validates the FixedIntervalSync settings
func (i *FixedIntervalSync) ValidateFixedIntervalSync(fldPath *field.Path) field.ErrorList {
	var allErrs field.ErrorList
	if i == nil {
		return append(allErrs, field.Required(fldPath, "fixedInterval sync config params are missing"))
	}
	if i.Seconds <= 0 {
		allErrs = append(allErrs, field.Invalid(fldPath.Child("seconds"), i.Seconds, apimachineryvalidation.IsNegativeErrorMsg))
	}
	return allErrs
}

// ApplyDefaults applies default values to the FleetAutoscaler
func (fas *FleetAutoscaler) ApplyDefaults() {
	if fas.Spec.Sync == nil {
		fas.Spec.Sync = &FleetAutoscalerSync{}
	}
	if fas.Spec.Sync.Type == "" {
		fas.Spec.Sync.Type = FixedIntervalSyncType
	}
	if fas.Spec.Sync.FixedInterval.Seconds == 0 {
		fas.Spec.Sync.FixedInterval.Seconds = defaultIntervalSyncSeconds
	}
}