balancer's Introduction

balancer

Simple, generic, domain-agnostic balancing algorithms for vinxi.

Currently provides random and roundrobin distribution algorithms. New algorithms may be added in the future.

Installation

go get -u gopkg.in/vinxi/balancer.v0

API

See godoc reference.

Example

Use as vinxi middleware

package main

import (
  "fmt"
  "gopkg.in/vinxi/balancer.v0"
  "gopkg.in/vinxi/forward.v0"
  "gopkg.in/vinxi/vinxi.v0"
  "net/http"
)

func main() {
  servers := []string{
    "http://www.nytimes.com",
    "http://www.repubblica.it",
    "http://elpais.com",
  }

  // Create the balancer
  lb := balancer.New(servers...)

  // Use custom handler in case of error
  lb.OnError(func(err error, w http.ResponseWriter, r *http.Request, h http.Handler) {
    fmt.Printf("Error: %s\n", err)
    w.WriteHeader(http.StatusBadGateway)
    w.Write([]byte("Error: " + err.Error()))
  })

  // Create a new vinxi proxy
  vs := vinxi.NewServer(vinxi.ServerOptions{Port: 3100})

  vs.Use(lb)

  fw, _ := forward.New(forward.PassHostHeader(true))
  vs.UseFinalHandler(fw)

  fmt.Printf("Server listening on port: %d\n", 3100)
  err := vs.Listen()
  if err != nil {
    fmt.Errorf("Error: %s\n", err)
  }
}

Round-robin balancing

package main

import (
  "fmt"
  "gopkg.in/vinxi/balancer.v0"
)

func main() {
  servers := []string{
    "http://1.server.com",
    "http://2.server.com",
    "http://3.server.com",
  }

  lb := balancer.NewRoundRobin()

  for i := 0; i < 9; i++ {
    fmt.Println("Next balance round...")
    server, err := lb.Balance(servers)
    if err != nil {
      fmt.Printf("Error: %s\n", err)
      return
    }
    fmt.Printf("Next target server: %s\n", server)
  }
}