activator

README

About the Activator

The name activator is actually a misnomer, since after Knative 0.2, the activator no longer activates inactive Revisions.

The only responsibilities of the activator are:

• Receiving & buffering requests for inactive Revisions.
• Reporting metrics to the autoscaler.
• Retrying requests to a Revision after the autoscaler scales such Revision based on the reported metrics.

Documentation

Index

• Constants
• Variables
• type Reporter
  • func NewStatsReporter() (*Reporter, error)
  • func (r *Reporter) ReportRequestCount(ns, service, config, rev string, responseCode, numTries int, v int64) error
  • func (r *Reporter) ReportResponseTime(ns, service, config, rev string, responseCode int, d time.Duration) error
• type RevisionID
  • func (rev RevisionID) String() string
• type StatsReporter
• type Throttler
  • func NewThrottler(params queue.BreakerParams, ...) *Throttler
  • func (t *Throttler) Remove(rev RevisionID)
  • func (t *Throttler) Try(rev RevisionID, function func()) error
  • func (t *Throttler) UpdateCapacity(rev RevisionID, size int) error

Constants

const (
	// Name is the name of the component.
	Name = "activator"
	// K8sServiceName is the name of the activator Kubernetes service.
	K8sServiceName = "activator-service"
	// RevisionHeaderName is the header key for revision name.
	RevisionHeaderName string = "knative-serving-revision"
	// RevisionHeaderNamespace is the header key for revision's namespace.
	RevisionHeaderNamespace string = "knative-serving-namespace"
)

Variables

var ErrActivatorOverload = errors.New("activator overload")

ErrActivatorOverload indicates that throttler has no free slots to buffer the request.

Types

type Reporter

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

Reporter holds cached metric objects to report autoscaler metrics

func NewStatsReporter

func NewStatsReporter() (*Reporter, error)

NewStatsReporter creates a reporter that collects and reports activator metrics

func (*Reporter) ReportRequestCount

func (r *Reporter) ReportRequestCount(ns, service, config, rev string, responseCode, numTries int, v int64) error

ReportRequestCount captures request count metric with value v.

func (*Reporter) ReportResponseTime

func (r *Reporter) ReportResponseTime(ns, service, config, rev string, responseCode int, d time.Duration) error

ReportResponseTime captures response time requests

type RevisionID

type RevisionID struct {
	Namespace string
	Name      string
}

RevisionID is the combination of namespace and revision name

func (RevisionID) String

func (rev RevisionID) String() string

String returns the namespaced name of the RevisionID.

type StatsReporter

type StatsReporter interface {
	ReportRequestCount(ns, service, config, rev string, responseCode, numTries int, v int64) error
	ReportResponseTime(ns, service, config, rev string, responseCode int, d time.Duration) error
}

StatsReporter defines the interface for sending activator metrics

type Throttler

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

Throttler keeps the mapping of Revisions to Breakers and allows updating max concurrency dynamically of respective Breakers. Max concurrency is essentially the number of semaphore tokens the Breaker has in rotation. The manipulation of the parameter is done via `UpdateCapacity()` method. It enables the use case to start with max concurrency set to 0 (no requests are sent because no endpoints are available) and gradually increase its value depending on the external condition (e.g. new endpoints become available)

func NewThrottler

func NewThrottler(
	params queue.BreakerParams,
	endpointsInformer corev1informers.EndpointsInformer,
	sksLister netlisters.ServerlessServiceLister,
	revisionLister servinglisters.RevisionLister,
	logger *zap.SugaredLogger) *Throttler

NewThrottler creates a new Throttler.

func (*Throttler) Remove

func (t *Throttler) Remove(rev RevisionID)

Remove deletes the breaker from the bookkeeping.

func (*Throttler) Try

func (t *Throttler) Try(rev RevisionID, function func()) error

Try potentially registers a new breaker in our bookkeeping and executes the `function` on the Breaker. It returns an error if either breaker doesn't have enough capacity, or breaker's registration didn't succeed, e.g. getting endpoints or update capacity failed.

func (*Throttler) UpdateCapacity

func (t *Throttler) UpdateCapacity(rev RevisionID, size int) error

UpdateCapacity updates the max concurrency of the Breaker corresponding to a revision.