ratelimiter

Documentation

Index

• Constants
• type KeyFunc
• type Option
  • func WithBlockedCountMetric(m *prometheus.GaugeVec) Option
  • func WithBurstSize(burst int) Option
  • func WithCacheMaxSize(size int64) Option
  • func WithCachedEntriesMetric(m *prometheus.GaugeVec) Option
  • func WithCachedRequestsMetric(m *prometheus.CounterVec) Option
  • func WithLimitPerSecond(limit float64) Option
  • func WithNow(now func() time.Time) Option
• type RateLimiter
  • func New(name string, opts ...Option) *RateLimiter
  • func (rl *RateLimiter) Middleware(handler http.Handler) http.Handler
  • func (rl *RateLimiter) RequestAllowed(r *http.Request) bool

Constants

const (
	// DefaultSourceIPLimitPerSecond is the limit per second that rate.Limiter
	// needs to generate tokens every second.
	// The default value is 20 requests per second.
	DefaultSourceIPLimitPerSecond = 20.0
	// DefaultSourceIPBurstSize is the maximum burst allowed per rate limiter.
	// E.g. The first 100 requests within 1s will succeed, but the 101st will fail.
	DefaultSourceIPBurstSize = 100

	// based on an avg ~4,000 unique IPs per minute
	// https://log.gprd.gitlab.net/app/lens#/edit/f7110d00-2013-11ec-8c8e-ed83b5469915?_g=h@e78830b
	DefaultSourceIPCacheSize = 5000
)

Types

type KeyFunc

type KeyFunc func(*http.Request) string

KeyFunc returns unique identifier for the subject of rate limit(e.g. client IP or domain)

type Option

type Option func(*RateLimiter)

Option function to configure a RateLimiter

func WithBlockedCountMetric

func WithBlockedCountMetric(m *prometheus.GaugeVec) Option

WithBlockedCountMetric configures metric reporting how many requests were blocked

func WithBurstSize

func WithBurstSize(burst int) Option

WithBurstSize configures burst per key for the RateLimiter

func WithCacheMaxSize

func WithCacheMaxSize(size int64) Option

WithCacheMaxSize configures cache size for ratelimiter

func WithCachedEntriesMetric

func WithCachedEntriesMetric(m *prometheus.GaugeVec) Option

WithCachedEntriesMetric configures metric reporting how many keys are currently stored in the rate-limiter cache

func WithCachedRequestsMetric

func WithCachedRequestsMetric(m *prometheus.CounterVec) Option

WithCachedRequestsMetric configures metric for how many times we ask key cache

func WithLimitPerSecond

func WithLimitPerSecond(limit float64) Option

WithLimitPerSecond allows configuring limit per second for RateLimiter

func WithNow

func WithNow(now func() time.Time) Option

WithNow replaces the RateLimiter now function

type RateLimiter

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

RateLimiter holds an LRU cache of elements to be rate limited. It uses "golang.org/x/time/rate" as its Token Bucket rate limiter per source IP entry. See example https://www.fatalerrors.org/a/design-and-implementation-of-time-rate-limiter-for-golang-standard-library.html It also holds a now function that can be mocked in unit tests.

func New

func New(name string, opts ...Option) *RateLimiter

New creates a new RateLimiter with default values that can be configured via Option functions

func (*RateLimiter) Middleware

func (rl *RateLimiter) Middleware(handler http.Handler) http.Handler

Middleware returns middleware for rate-limiting clients

func (*RateLimiter) RequestAllowed

func (rl *RateLimiter) RequestAllowed(r *http.Request) bool

RequestAllowed checks that the real remote IP address is allowed to perform an operation