roundrobin

Documentation

Overview

Package roundrobin implements dynamic weighted round robin load balancer http handler

Index

• Constants
• func SetDefaultWeight(weight int) error
• type CookieOptions
• type LBOption
  • func EnableStickySession(stickySession *StickySession) LBOption
  • func ErrorHandler(h utils.ErrorHandler) LBOption
  • func RoundRobinLogger(l utils.Logger) LBOption
  • func RoundRobinRequestRewriteListener(rrl RequestRewriteListener) LBOption
• type Meter
• type NewMeterFn
• type Rebalancer
  • func NewRebalancer(handler balancerHandler, opts ...RebalancerOption) (*Rebalancer, error)
  • func (rb *Rebalancer) RemoveServer(u *url.URL) error
  • func (rb *Rebalancer) ServeHTTP(w http.ResponseWriter, req *http.Request)
  • func (rb *Rebalancer) Servers() []*url.URL
  • func (rb *Rebalancer) UpsertServer(u *url.URL, options ...ServerOption) error
  • func (rb *Rebalancer) Wrap(next balancerHandler) error
• type RebalancerOption
  • func RebalancerBackoff(d time.Duration) RebalancerOption
  • func RebalancerErrorHandler(h utils.ErrorHandler) RebalancerOption
  • func RebalancerLogger(l utils.Logger) RebalancerOption
  • func RebalancerMeter(newMeter NewMeterFn) RebalancerOption
  • func RebalancerRequestRewriteListener(rrl RequestRewriteListener) RebalancerOption
  • func RebalancerStickySession(stickySession *StickySession) RebalancerOption
• type RequestRewriteListener
• type RoundRobin
  • func New(next http.Handler, opts ...LBOption) (*RoundRobin, error)
  • func (r *RoundRobin) Next() http.Handler
  • func (r *RoundRobin) NextServer() (*url.URL, error)
  • func (r *RoundRobin) RemoveServer(u *url.URL) error
  • func (r *RoundRobin) ServeHTTP(w http.ResponseWriter, req *http.Request)
  • func (r *RoundRobin) ServerWeight(u *url.URL) (int, bool)
  • func (r *RoundRobin) Servers() []*url.URL
  • func (r *RoundRobin) UpsertServer(u *url.URL, options ...ServerOption) error
• type ServerOption
  • func Weight(w int) ServerOption
• type StickySession
  • func NewStickySession(cookieName string) *StickySession
  • func NewStickySessionWithOptions(cookieName string, options CookieOptions) *StickySession
  • func (s *StickySession) GetBackend(req *http.Request, servers []*url.URL) (*url.URL, bool, error)
  • func (s *StickySession) StickBackend(backend *url.URL, w *http.ResponseWriter)

Constants

const (
	// FSMMaxWeight is the maximum weight that handler will set for the server
	FSMMaxWeight = 4096
	// FSMGrowFactor Multiplier for the server weight
	FSMGrowFactor = 4
)

Functions

func SetDefaultWeight

func SetDefaultWeight(weight int) error

SetDefaultWeight sets the default server weight

Types

type CookieOptions

type CookieOptions struct {
	HTTPOnly bool
	Secure   bool

	Path    string
	Domain  string
	Expires time.Time

	MaxAge   int
	SameSite http.SameSite
}

CookieOptions has all the options one would like to set on the affinity cookie

type LBOption

type LBOption func(*RoundRobin) error

LBOption provides options for load balancer

func EnableStickySession

func EnableStickySession(stickySession *StickySession) LBOption

EnableStickySession enable sticky session

func ErrorHandler

func ErrorHandler(h utils.ErrorHandler) LBOption

ErrorHandler is a functional argument that sets error handler of the server

func RoundRobinLogger

func RoundRobinLogger(l utils.Logger) LBOption

RoundRobinLogger defines the logger the round robin load balancer will use.

func RoundRobinRequestRewriteListener

func RoundRobinRequestRewriteListener(rrl RequestRewriteListener) LBOption

RoundRobinRequestRewriteListener is a functional argument that sets error handler of the server

type Meter

type Meter interface {
	Rating() float64
	Record(int, time.Duration)
	IsReady() bool
}

Meter measures server performance and returns it's relative value via rating

type NewMeterFn

type NewMeterFn func() (Meter, error)

NewMeterFn type of functions to create new Meter

type Rebalancer

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

Rebalancer increases weights on servers that perform better than others. It also rolls back to original weights if the servers have changed. It is designed as a wrapper on top of the roundrobin.

func NewRebalancer

func NewRebalancer(handler balancerHandler, opts ...RebalancerOption) (*Rebalancer, error)

NewRebalancer creates a new Rebalancer

func (*Rebalancer) RemoveServer

func (rb *Rebalancer) RemoveServer(u *url.URL) error

RemoveServer remove a server

func (*Rebalancer) ServeHTTP

func (rb *Rebalancer) ServeHTTP(w http.ResponseWriter, req *http.Request)

func (*Rebalancer) Servers

func (rb *Rebalancer) Servers() []*url.URL

Servers gets all servers

func (*Rebalancer) UpsertServer

func (rb *Rebalancer) UpsertServer(u *url.URL, options ...ServerOption) error

UpsertServer upsert a server

func (*Rebalancer) Wrap

func (rb *Rebalancer) Wrap(next balancerHandler) error

Wrap sets the next handler to be called by rebalancer handler.

type RebalancerOption

type RebalancerOption func(*Rebalancer) error

RebalancerOption - functional option setter for rebalancer

func RebalancerBackoff

func RebalancerBackoff(d time.Duration) RebalancerOption

RebalancerBackoff sets a beck off duration

func RebalancerErrorHandler

func RebalancerErrorHandler(h utils.ErrorHandler) RebalancerOption

RebalancerErrorHandler is a functional argument that sets error handler of the server

func RebalancerLogger

func RebalancerLogger(l utils.Logger) RebalancerOption

RebalancerLogger defines the logger the rebalancer will use.

func RebalancerMeter

func RebalancerMeter(newMeter NewMeterFn) RebalancerOption

RebalancerMeter sets a Meter builder function

func RebalancerRequestRewriteListener

func RebalancerRequestRewriteListener(rrl RequestRewriteListener) RebalancerOption

RebalancerRequestRewriteListener is a functional argument that sets error handler of the server

func RebalancerStickySession

func RebalancerStickySession(stickySession *StickySession) RebalancerOption

RebalancerStickySession sets a sticky session

type RequestRewriteListener

type RequestRewriteListener func(oldReq *http.Request, newReq *http.Request)

RequestRewriteListener function to rewrite request

type RoundRobin

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

RoundRobin implements dynamic weighted round robin load balancer http handler

func New

func New(next http.Handler, opts ...LBOption) (*RoundRobin, error)

New created a new RoundRobin

func (*RoundRobin) Next

func (r *RoundRobin) Next() http.Handler

Next returns the next handler

func (*RoundRobin) NextServer

func (r *RoundRobin) NextServer() (*url.URL, error)

NextServer gets the next server

func (*RoundRobin) RemoveServer

func (r *RoundRobin) RemoveServer(u *url.URL) error

RemoveServer remove a server

func (*RoundRobin) ServeHTTP

func (r *RoundRobin) ServeHTTP(w http.ResponseWriter, req *http.Request)

func (*RoundRobin) ServerWeight

func (r *RoundRobin) ServerWeight(u *url.URL) (int, bool)

ServerWeight gets the server weight

func (*RoundRobin) Servers

func (r *RoundRobin) Servers() []*url.URL

Servers gets servers URL

func (*RoundRobin) UpsertServer

func (r *RoundRobin) UpsertServer(u *url.URL, options ...ServerOption) error

UpsertServer In case if server is already present in the load balancer, returns error

type ServerOption

type ServerOption func(*server) error

ServerOption provides various options for server, e.g. weight

func Weight

func Weight(w int) ServerOption

Weight is an optional functional argument that sets weight of the server

type StickySession

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

StickySession is a mixin for load balancers that implements layer 7 (http cookie) session affinity

func NewStickySession

func NewStickySession(cookieName string) *StickySession

NewStickySession creates a new StickySession

func NewStickySessionWithOptions

func NewStickySessionWithOptions(cookieName string, options CookieOptions) *StickySession

NewStickySessionWithOptions creates a new StickySession whilst allowing for options to shape its affinity cookie such as "httpOnly" or "secure"

func (*StickySession) GetBackend

func (s *StickySession) GetBackend(req *http.Request, servers []*url.URL) (*url.URL, bool, error)

GetBackend returns the backend URL stored in the sticky cookie, iff the backend is still in the valid list of servers.

func (*StickySession) StickBackend

func (s *StickySession) StickBackend(backend *url.URL, w *http.ResponseWriter)

StickBackend creates and sets the cookie