ratelimit

Documentation

Overview

Package ratelimit implements rate limiting functionality for the proxy.

It provides per process rate limiting. It can be configured globally, or based on routes. Rate limiting can be lookuped based on HTTP headers like X-Forwarded-For or Authorization.

Lookuper Type - Authorization Header

This lookuper will use the content of the Authorization header to calculate rate limiting. This will work for Bearer tokens or Basic Auth without change of the rate limiter configuration.

Lookuper Type - X-Forwarded-For Header

This lookuper will use the remote IP of the origin request to calculate rate limiting. If there is no such header it will use the remote IP of the request. This is the default Lookuper and may be the one most users want to use.

Usage

When imported as a package, the Registry can be used to hold the rate limiters and their settings. On a higher level, rate limiter settings can be simply passed to skipper as part of the skipper.Options object, or defined as command line flags.

The following command starts skipper with default X-Forwarded-For Lookuper, that will start to rate limit after 5 requests within 60s from the same client

% skipper -ratelimits type=client,max-hits=5,time-window=60s

The following configuration will rate limit /foo after 2 requests within 90s from the same requester and all other requests after 20 requests within 60s from the same client

% cat ratelimit.eskip
foo: Path("/foo") -> clientRatelimit(2,"1m30s") -> "http://www.example.org/foo"
rest: * -> clientRatelimit(20,"1m") -> "http://www.example.net/"
% skipper -enable-ratelimits -routes-file=ratelimit.eskip

The following configuration will rate limit requests after 100 requests within 1 minute with the same Authorization Header

% cat ratelimit-auth.eskip
all: * -> clientRatelimit(100,"1m","auth") -> "http://www.example.org/"
% skipper -enable-ratelimits -routes-file=ratelimit-auth.eskip

The following configuration will rate limit requests to /login after 10 requests summed across all skipper peers within one hour from the same requester.

% cat ratelimit.eskip
foo: Path("/login") -> clientRatelimit(10,"1h") -> "http://www.example.org/login"
rest: * -> "http://www.example.net/"
% skipper -enable-ratelimits -routes-file=ratelimit.eskip -enable-swarm

Rate limiter settings can be applied globally via command line flags or within routing settings.

Settings - Type

Defines the type of the rate limiter. There are types that only use local state information and others that use cluster information using swarm.Swarm to exchange information. Types that use instance local information are ServiceRatelimit to be used to protect backends and ClientRatelimit to protect from too chatty clients. Types that use cluster information are ClusterServiceRatelimit to be used to protect backends and and ClusterClientRatelimit to protect from too chatty clients. ClusterClientRatelimit should be carefully tested with your current memory settings (about 15MB for 100.000 attackers per filter), but the use cases are to protect from login attacks, user enumeration or DDoS attacks.

Settings - MaxHits

Defines the maximum number of requests per user within a TimeWindow.

Settings - TimeWindow

Defines the time window until rate limits will be enforced, if maximum number of requests are exceeded. This is defined as a string representation of Go's time.Duration, e.g. 1m30s.

Settings - Lookuper

Defines an optional configuration to choose which Header should be used to group client requests. It accepts the default "x-forwarded-for" or "auth"

HTTP Response

In case of rate limiting, the HTTP response status will be 429 Too Many Requests and two headers will be set.

One which shows the maximum requests per hour:

X-Rate-Limit: 6000

And another indicating how long (in seconds) to wait before making a new request:

Retry-After: 3600

Both are based on RFC 6585.

Registry

The active rate limiters are stored in a registry. They are created based on routes or command line flags. The registry synchronizes access to the shared rate limiters. A registry has default settings that it will apply and that it will use the disable rate limiter in case it's not defined in the configuration or not global enabled.

Index

• Constants
• type AuthLookuper
  • func NewAuthLookuper() AuthLookuper
  • func (AuthLookuper) Lookup(req *http.Request) string
• type Lookuper
• type Ratelimit
  • func (l *Ratelimit) Allow(s string) bool
  • func (l *Ratelimit) Close()
  • func (l *Ratelimit) Delta(s string) time.Duration
  • func (l *Ratelimit) Resize(s string, i int)
  • func (l *Ratelimit) RetryAfter(s string) int
• type RatelimitType
• type Registry
  • func NewRegistry(settings ...Settings) *Registry
  • func NewSwarmRegistry(swarm Swarmer, settings ...Settings) *Registry
  • func (r *Registry) Check(req *http.Request) (Settings, int)
  • func (r *Registry) Get(s Settings) *Ratelimit
• type SameBucketLookuper
  • func NewSameBucketLookuper() SameBucketLookuper
  • func (SameBucketLookuper) Lookup(*http.Request) string
• type Settings
  • func (s Settings) Empty() bool
  • func (s Settings) String() string
• type Swarmer
• type XForwardedForLookuper
  • func NewXForwardedForLookuper() XForwardedForLookuper
  • func (XForwardedForLookuper) Lookup(req *http.Request) string

Constants

const (
	// Header is
	Header = "X-Rate-Limit"

	// RetryHeader is name of the header which will be used to indicate how
	// long a client should wait before making a new request
	RetryAfterHeader = "Retry-After"

	// ServiceRatelimitName is the name of the Ratelimit filter, which will be shown in log
	ServiceRatelimitName = "ratelimit"

	// LocalRatelimitName *deprecated*, use ClientRatelimitName instead
	LocalRatelimitName = "localRatelimit"

	// ClientRatelimitName is the name of the ClientRatelimit filter, which will be shown in log
	ClientRatelimitName = "clientRatelimit"

	// ClusterServiceRatelimitName is the name of the ClusterServiceRatelimit filter, which will be shown in log
	ClusterServiceRatelimitName = "clusterRatelimit"

	// ClusterClientRatelimitName is the name of the ClusterClientRatelimit filter, which will be shown in log
	ClusterClientRatelimitName = "clusterClientRatelimit"

	// DisableRatelimitName is the name of the DisableRatelimit, which will be shown in log
	DisableRatelimitName = "disableRatelimit"
)

const (
	DefaultMaxhits       = 20
	DefaultTimeWindow    = 1 * time.Second
	DefaultCleanInterval = 60 * time.Second
)

Types

type AuthLookuper

type AuthLookuper struct{}

AuthLookuper implements Lookuper interface and will select a bucket by Authorization header.

func NewAuthLookuper

func NewAuthLookuper() AuthLookuper

NewAuthLookuper returns an empty AuthLookuper

func (AuthLookuper) Lookup

func (AuthLookuper) Lookup(req *http.Request) string

Lookup returns the content of the Authorization header.

type Lookuper

type Lookuper interface {
	// Lookup is used to get the string which is used to define
	// how the bucket of a ratelimiter looks like, which is used
	// to decide to ratelimit or not. For example you can use the
	// X-Forwarded-For Header if you want to rate limit based on
	// source ip behind a proxy/loadbalancer or the Authorization
	// Header for request per token or user.
	Lookup(*http.Request) string
}

Lookuper makes it possible to be more flexible for ratelimiting.

type Ratelimit

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

Ratelimit is a proxy object that delegates to limiter implemetations and stores settings for the ratelimiter

func (*Ratelimit) Allow

func (l *Ratelimit) Allow(s string) bool

Allow returns true if the s is not ratelimited, false if it is ratelimited

func (*Ratelimit) Close

func (l *Ratelimit) Close()

Close will stop any cleanup goroutines in underlying limiter implementation.

func (*Ratelimit) Delta

func (l *Ratelimit) Delta(s string) time.Duration

func (*Ratelimit) Resize

func (l *Ratelimit) Resize(s string, i int)

func (*Ratelimit) RetryAfter

func (l *Ratelimit) RetryAfter(s string) int

RetryAfter informs how many seconds to wait for the next request

type RatelimitType

type RatelimitType int

RatelimitType defines the type of the used ratelimit

const (
	// NoRatelimit is not used
	NoRatelimit RatelimitType = iota

	// ServiceRatelimit is used to have a simple rate limit for a
	// backend service, which is calculated and measured within
	// each instance
	ServiceRatelimit

	// LocalRatelimit *deprecated* will be replaced by ClientRatelimit
	LocalRatelimit

	// ClientRatelimit is used to have a simple local rate limit
	// per user for a backend, which is calculated and measured
	// within each instance. One filter consumes memory calculated
	// by the following formular, where N is the number of
	// individual clients put into the same bucket, M the maximum
	// number of requests allowed:
	//
	//    memory = N * M * 15 byte
	//
	// For example /login protection 100.000 attacker, 10 requests
	// for 1 hour will use roughly 14.6 MB.
	ClientRatelimit

	// ClusterServiceRatelimit is used to calculate a rate limit
	// for a whole skipper fleet for a backend service, needs
	// swarm to be enabled with -enable-swarm.
	ClusterServiceRatelimit

	// ClusterClientRatelimit is used to calculate a rate limit
	// for a whole skipper fleet per user for a backend, needs
	// swarm to be enabled with -enable-swarm.
	// One filter consumes memory calculated
	// by the following formular, where N is the number of
	// individual clients put into the same bucket, M the maximum
	// number of requests allowed, S the number of skipper peers:
	//
	//    memory = N * M * 15 + S * len(peername)
	//
	// For example /login protection 100.000 attacker, 10 requests
	// for 1 hour, 100 skipper peers with each a name of 8
	// characters will use roughly 14.7 MB.
	ClusterClientRatelimit

	// DisableRatelimit is used to disable rate limit
	DisableRatelimit
)

type Registry

type Registry struct {
	sync.Mutex
	// contains filtered or unexported fields
}

Registry objects hold the active ratelimiters, ensure synchronized access to them, apply default settings and recycle the idle ratelimiters.

func NewRegistry

func NewRegistry(settings ...Settings) *Registry

NewRegistry initializes a registry with the provided default settings.

func NewSwarmRegistry

func NewSwarmRegistry(swarm Swarmer, settings ...Settings) *Registry

NewSwarmRegistry initializes a registry with an optional swarm and the provided default settings. If swarm is nil, clusterRatelimits will be replaced by voidRatelimit, which is a noop limiter implementation.

func (*Registry) Check

func (r *Registry) Check(req *http.Request) (Settings, int)

Check returns Settings used and the retry-after duration in case of request is ratelimitted. Otherwise return the Settings and 0.

func (*Registry) Get

func (r *Registry) Get(s Settings) *Ratelimit

Get returns a Ratelimit instance for provided Settings

type SameBucketLookuper

type SameBucketLookuper struct{}

SameBucketLookuper implements Lookuper interface and will always match to the same bucket.

func NewSameBucketLookuper

func NewSameBucketLookuper() SameBucketLookuper

NewSameBucketLookuper returns a SameBucketLookuper.

func (SameBucketLookuper) Lookup

func (SameBucketLookuper) Lookup(*http.Request) string

Lookup will always return "s" to select the same bucket.

type Settings

type Settings struct {
	// Type of the chosen rate limiter
	Type RatelimitType

	// Lookuper to decide which data to use to identify the same
	// bucket (for example how to lookup the client identifier)
	Lookuper Lookuper

	// MaxHits the maximum number of hits for a time duration
	// allowed in the same bucket.
	MaxHits int

	// TimeWindow is the time duration that is valid for hits to
	// be counted in the rate limit.
	TimeWindow time.Duration

	// CleanInterval is the duration old data can expire, because
	// need to cleanup data in for example client ratelimits.
	CleanInterval time.Duration
}

Settings configures the chosen rate limiter

func (Settings) Empty

func (s Settings) Empty() bool

func (Settings) String

func (s Settings) String() string

type Swarmer

type Swarmer interface {
	// ShareValue is used to share the local information with its peers.
	ShareValue(string, interface{}) error
	// Values is used to get global information about current rates.
	Values(string) map[string]interface{}
}

Swarmer interface defines the requirement for a Swarm, for use as an exchange method for cluster ratelimits: ratelimit.ClusterServiceRatelimit and ratelimit.ClusterClientRatelimit.

type XForwardedForLookuper

type XForwardedForLookuper struct{}

XForwardedForLookuper implements Lookuper interface and will select a bucket by X-Forwarded-For header or clientIP.

func NewXForwardedForLookuper

func NewXForwardedForLookuper() XForwardedForLookuper

NewXForwardedForLookuper returns an empty XForwardedForLookuper

func (XForwardedForLookuper) Lookup

func (XForwardedForLookuper) Lookup(req *http.Request) string

Lookup returns the content of the X-Forwarded-For header or the clientIP if not set.