autoscaler

package
v0.8.1 Latest Latest
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 Go to latest Published: Aug 27, 2019 License: Apache-2.0 Imports: 38 Imported by: 0

README

Scaling documentation has moved to the docs folder.

Documentation

Overview

Package autoscaler calculates the number of pods necessary for the desired level of concurrency per pod (stableConcurrencyPerPod). It operates in two modes, stable mode and panic mode.

Stable mode calculates the average concurrency observed over the last 60 seconds and adjusts the observed pod count to achieve the target value. Current observed pod count is the number of unique pod names which show up in the last 60 seconds.

Panic mode calculates the average concurrency observed over the last 6 seconds and adjusts the observed pod count to achieve the stable target value. Panic mode is engaged when the observed 6 second average concurrency reaches 2x the target stable concurrency. Panic mode will last at least 60 seconds--longer if the 2x threshold is repeatedly breached. During panic mode the number of pods is never decreased in order to prevent flapping.

Package autoscaler supports both single-tenant (one autoscaler per revision) and multitenant (one autoscaler for all revisions) autoscalers; config/controller.yaml determines which kind of autoscaler is used.

Index

Constants

View Source 
const (

	// BucketSize is the size of the buckets of stats we create.
	BucketSize = 2 * time.Second
)
View Source 
const (
	// ConfigName is the name of the config map of the autoscaler.
	ConfigName = "config-autoscaler"
)

Variables

View Source 
var (
	// ErrNoData denotes that the collector could not calculate data.
	ErrNoData = errors.New("no data available")

	// ErrNotScraping denotes that the collector is not collecting metrics for the given resource.
	ErrNotScraping = errors.New("the requested resource is not being scraped")
)

Functions

This section is empty.

Types

type Autoscaler 

type Autoscaler struct {
	// contains filtered or unexported fields
}

Autoscaler stores current state of an instance of an autoscaler.

func New 

func New(
	namespace string,
	revision string,
	metricClient MetricClient,
	podCounter resources.ReadyPodCounter,
	deciderSpec DeciderSpec,
	reporter StatsReporter) (*Autoscaler, error)

New creates a new instance of autoscaler

func (*Autoscaler) Scale 

func (a *Autoscaler) Scale(ctx context.Context, now time.Time) (desiredPodCount int32, excessBC int32, validScale bool)

Scale calculates the desired scale based on current statistics given the current time. desiredPodCount is the calculated pod count the autoscaler would like to set. validScale signifies whether the desiredPodCount should be applied or not.

func (*Autoscaler) Update 

func (a *Autoscaler) Update(deciderSpec DeciderSpec) error

Update reconfigures the UniScaler according to the DeciderSpec.

type Collector 

type Collector interface {
	// CreateOrUpdate either creates a collection for the given metric or update it, should
	// it already exist.
	CreateOrUpdate(*av1alpha1.Metric) error
	// Record allows stats to be captured that came from outside the Collector.
	Record(key types.NamespacedName, stat Stat)
	// Delete deletes a Metric and halts collection.
	Delete(string, string) error
}

Collector starts and stops metric collection for a given entity.

type Config 

type Config struct {
	// Feature flags.
	EnableScaleToZero bool

	// Target concurrency knobs for different container concurrency configurations.
	ContainerConcurrencyTargetFraction float64
	ContainerConcurrencyTargetDefault  float64
	// NB: most of our computations are in floats, so this is float to avoid casting.
	TargetBurstCapacity float64

	// General autoscaler algorithm configuration.
	MaxScaleUpRate           float64
	StableWindow             time.Duration
	PanicWindowPercentage    float64
	PanicThresholdPercentage float64
	// Deprecated in favor of PanicWindowPercentage.
	PanicWindow  time.Duration
	TickInterval time.Duration

	ScaleToZeroGracePeriod time.Duration
}

Config defines the tunable autoscaler parameters +k8s:deepcopy-gen=true

func NewConfigFromConfigMap 

func NewConfigFromConfigMap(configMap *corev1.ConfigMap) (*Config, error)

NewConfigFromConfigMap creates a Config from the supplied ConfigMap

func NewConfigFromMap 

func NewConfigFromMap(data map[string]string) (*Config, error)

NewConfigFromMap creates a Config from the supplied map

func (*Config) DeepCopy 

func (in *Config) DeepCopy() *Config

DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new Config.

func (*Config) DeepCopyInto 

func (in *Config) DeepCopyInto(out *Config)

DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.

type Decider 

type Decider struct {
	metav1.ObjectMeta
	Spec   DeciderSpec
	Status DeciderStatus
}

Decider is a resource which observes the request load of a Revision and recommends a number of replicas to run. +k8s:deepcopy-gen=true

func (*Decider) DeepCopy 

func (in *Decider) DeepCopy() *Decider

DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new Decider.

func (*Decider) DeepCopyInto 

func (in *Decider) DeepCopyInto(out *Decider)

DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.

type DeciderSpec 

type DeciderSpec struct {
	TickInterval   time.Duration
	MaxScaleUpRate float64
	// The concurrency per pod that we target to maintain.
	// TargetConcurrency <= TotalConcurency.
	TargetConcurrency float64
	// The total concurrency that a pod can maintain.
	TotalConcurrency float64
	// The burst capacity that user wants to maintain without queing at the POD level.
	// Note, that queueing still might happen due to the non-ideal load balancing.
	TargetBurstCapacity float64
	PanicThreshold      float64
	// StableWindow is needed to determine when to exit panicmode.
	StableWindow time.Duration
	// The name of the k8s service for pod information.
	ServiceName string
}

DeciderSpec is the parameters in which the Revision should scaled.

type DeciderStatus 

type DeciderStatus struct {
	// DesiredScale is the target number of instances that autoscaler
	// this revision needs.
	DesiredScale int32

	// ExcessBurstCapacity is the difference between spare capacity
	// (how many more concurrent requests the pods in the revision
	// deployment can serve) and the configured target burst capacity.
	// If this number is negative: Activator will be threaded in
	// the request path by the PodAutoscaler controller.
	ExcessBurstCapacity int32
}

DeciderStatus is the current scale recommendation.

type MetricClient 

type MetricClient interface {
	// StableAndPanicConcurrency returns both the stable and the panic concurrency
	// for the given replica as of the given time.
	StableAndPanicConcurrency(key types.NamespacedName, now time.Time) (float64, float64, error)

	// StableAndPanicOPS returns both the stable and the panic OPS
	// for the given replica as of the given time.
	StableAndPanicOPS(key types.NamespacedName, now time.Time) (float64, float64, error)
}

MetricClient surfaces the metrics that can be obtained via the collector.

type MetricCollector 

type MetricCollector struct {
	// contains filtered or unexported fields
}

MetricCollector manages collection of metrics for many entities.

func NewMetricCollector 

func NewMetricCollector(statsScraperFactory StatsScraperFactory, logger *zap.SugaredLogger) *MetricCollector

NewMetricCollector creates a new metric collector.

func (*MetricCollector) CreateOrUpdate 

func (c *MetricCollector) CreateOrUpdate(metric *av1alpha1.Metric) error

CreateOrUpdate either creates a collection for the given metric or update it, should it already exist. Map access optimized via double-checked locking.

func (*MetricCollector) Delete 

func (c *MetricCollector) Delete(namespace, name string) error

Delete deletes a Metric and halts collection.

func (*MetricCollector) Record 

func (c *MetricCollector) Record(key types.NamespacedName, stat Stat)

Record records a stat that's been generated outside of the metric collector.

func (*MetricCollector) StableAndPanicConcurrency 

func (c *MetricCollector) StableAndPanicConcurrency(key types.NamespacedName, now time.Time) (float64, float64, error)

StableAndPanicConcurrency returns both the stable and the panic concurrency. It may truncate metric buckets as a side-effect.

func (*MetricCollector) StableAndPanicOPS 

func (c *MetricCollector) StableAndPanicOPS(key types.NamespacedName, now time.Time) (float64, float64, error)

StableAndPanicOPS returns both the stable and the panic OPS. It may truncate metric buckets as a side-effect.

type MetricProvider 

type MetricProvider struct {
	// contains filtered or unexported fields
}

MetricProvider is a provider to back a custom-metrics API implementation.

func NewMetricProvider 

func NewMetricProvider(metricClient MetricClient) *MetricProvider

NewMetricProvider creates a new MetricProvider.

func (*MetricProvider) GetMetricByName 

func (p *MetricProvider) GetMetricByName(name types.NamespacedName, info provider.CustomMetricInfo) (*cmetrics.MetricValue, error)

GetMetricByName implements the interface.

func (*MetricProvider) GetMetricBySelector 

func (p *MetricProvider) GetMetricBySelector(namespace string, selector labels.Selector, info provider.CustomMetricInfo) (*cmetrics.MetricValueList, error)

GetMetricBySelector implements the interface.

func (*MetricProvider) ListAllMetrics 

func (p *MetricProvider) ListAllMetrics() []provider.CustomMetricInfo

ListAllMetrics implements the interface.

type MultiScaler 

type MultiScaler struct {
	// contains filtered or unexported fields
}

MultiScaler maintains a collection of Uniscalers.

func NewMultiScaler 

func NewMultiScaler(
	stopCh <-chan struct{},
	uniScalerFactory UniScalerFactory,
	logger *zap.SugaredLogger) *MultiScaler

NewMultiScaler constructs a MultiScaler.

func (*MultiScaler) Create 

func (m *MultiScaler) Create(ctx context.Context, decider *Decider) (*Decider, error)

Create instantiates the desired Decider.

func (*MultiScaler) Delete 

func (m *MultiScaler) Delete(ctx context.Context, namespace, name string) error

Delete stops and removes a Decider.

func (*MultiScaler) Get 

func (m *MultiScaler) Get(ctx context.Context, namespace, name string) (*Decider, error)

Get return the current Decider.

func (*MultiScaler) Inform 

func (m *MultiScaler) Inform(event string) bool

Inform sends an update to the registered watcher function, if it is set.

func (*MultiScaler) Poke 

func (m *MultiScaler) Poke(key types.NamespacedName, stat Stat)

Poke checks if the autoscaler needs to be run immediately.

func (*MultiScaler) Update 

func (m *MultiScaler) Update(ctx context.Context, decider *Decider) (*Decider, error)

Update applied the desired DeciderSpec to a currently running Decider.

func (*MultiScaler) Watch 

func (m *MultiScaler) Watch(fn func(string))

Watch registers a singleton function to call when DeciderStatus is updated.

type Reporter 

type Reporter struct {
	// contains filtered or unexported fields
}

Reporter holds cached metric objects to report autoscaler metrics

func NewStatsReporter 

func NewStatsReporter(podNamespace string, service string, config string, revision string) (*Reporter, error)

NewStatsReporter creates a reporter that collects and reports autoscaler metrics

func (*Reporter) ReportActualPodCount 

func (r *Reporter) ReportActualPodCount(v int64) error

ReportActualPodCount captures value v for actual pod count measure.

func (*Reporter) ReportDesiredPodCount 

func (r *Reporter) ReportDesiredPodCount(v int64) error

ReportDesiredPodCount captures value v for desired pod count measure.

func (*Reporter) ReportExcessBurstCapacity 

func (r *Reporter) ReportExcessBurstCapacity(v float64) error

ReportExcessBurstCapacity captures value v for excess target burst capacity.

func (*Reporter) ReportPanic 

func (r *Reporter) ReportPanic(v int64) error

ReportPanic captures value v for panic mode measure.

func (*Reporter) ReportPanicRequestConcurrency 

func (r *Reporter) ReportPanicRequestConcurrency(v float64) error

ReportPanicRequestConcurrency captures value v for panic request concurrency measure.

func (*Reporter) ReportRequestedPodCount 

func (r *Reporter) ReportRequestedPodCount(v int64) error

ReportRequestedPodCount captures value v for requested pod count measure.

func (*Reporter) ReportStableRequestConcurrency 

func (r *Reporter) ReportStableRequestConcurrency(v float64) error

ReportStableRequestConcurrency captures value v for stable request concurrency measure.

func (*Reporter) ReportTargetRequestConcurrency 

func (r *Reporter) ReportTargetRequestConcurrency(v float64) error

ReportTargetRequestConcurrency captures value v for target request concurrency measure.

type ServiceScraper 

type ServiceScraper struct {
	// contains filtered or unexported fields
}

ServiceScraper scrapes Revision metrics via a K8S service by sampling. Which pod to be picked up to serve the request is decided by K8S. Please see https://kubernetes.io/docs/concepts/services-networking/network-policies/ for details.

func NewServiceScraper 

func NewServiceScraper(metric *av1alpha1.Metric, counter resources.ReadyPodCounter) (*ServiceScraper, error)

NewServiceScraper creates a new StatsScraper for the Revision which the given Metric is responsible for.

func (*ServiceScraper) Scrape 

func (s *ServiceScraper) Scrape() (*StatMessage, error)

Scrape calls the destination service then sends it to the given stats channel.

type Stat 

type Stat struct {
	// The time the data point was received by autoscaler.
	Time *time.Time

	// The unique identity of this pod.  Used to count how many pods
	// are contributing to the metrics.
	PodName string

	// Average number of requests currently being handled by this pod.
	AverageConcurrentRequests float64

	// Part of AverageConcurrentRequests, for requests going through a proxy.
	AverageProxiedConcurrentRequests float64

	// Number of requests received since last Stat (approximately QPS).
	RequestCount float64

	// Part of RequestCount, for requests going through a proxy.
	ProxiedRequestCount float64
}

Stat defines a single measurement at a point in time

type StatMessage 

type StatMessage struct {
	Key  types.NamespacedName
	Stat Stat
}

StatMessage wraps a Stat with identifying information so it can be routed to the correct receiver.

type StatsReporter 

type StatsReporter interface {
	ReportDesiredPodCount(v int64) error
	ReportRequestedPodCount(v int64) error
	ReportActualPodCount(v int64) error
	ReportStableRequestConcurrency(v float64) error
	ReportPanicRequestConcurrency(v float64) error
	ReportTargetRequestConcurrency(v float64) error
	ReportExcessBurstCapacity(v float64) error
	ReportPanic(v int64) error
}

StatsReporter defines the interface for sending autoscaler metrics

type StatsScraper 

type StatsScraper interface {
	// Scrape scrapes the Revision queue metric endpoint.
	Scrape() (*StatMessage, error)
}

StatsScraper defines the interface for collecting Revision metrics

type StatsScraperFactory 

type StatsScraperFactory func(*av1alpha1.Metric) (StatsScraper, error)

StatsScraperFactory creates a StatsScraper for a given Metric.

type UniScaler 

type UniScaler interface {
	// Scale either proposes a number of replicas and available excess burst capacity,
	// or skips proposing. The proposal is requested at the given time.
	// The returned boolean is true if and only if a proposal was returned.
	Scale(context.Context, time.Time) (int32, int32, bool)

	// Update reconfigures the UniScaler according to the DeciderSpec.
	Update(DeciderSpec) error
}

UniScaler records statistics for a particular Decider and proposes the scale for the Decider's target based on those statistics.

type UniScalerFactory 

type UniScalerFactory func(*Decider) (UniScaler, error)

UniScalerFactory creates a UniScaler for a given PA using the given dynamic configuration.

Source Files

View all Source files

Directories

Path Synopsis
Package statserver provides a WebSocket server which receives autoscaler statistics, typically from queue proxy sidecar containers, and sends them to a channel.
 Package statserver provides a WebSocket server which receives autoscaler statistics, typically from queue proxy sidecar containers, and sends them to a channel.

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