flyinweb's blog

需求转而学习
         很多时候不少做开发的同学都认为技术更新的快，新技术、新概念层出不穷，大家乐此不疲的去跟随着所谓的“技术趋势”走在风头浪尖上，但其实往往忘记了一个最重要的问题“满足客户需求”。其实技术就是为满足需求服务的，用最小的代价来满足用户的需求，以最简单高效的方式来达到目标，就是每个开发者应该追求的。（不要因为自己的架构很简单就脸红拿不出手，只要你在满足用户当前需求的基础上对未来有所考虑，那么化繁为简就是一种能力的表现）

         SIP（服务集成平台）5.7版本中对于未来多个服务提供商，多种类型的服务，在每日几亿的调用压力下，需要找到一个解决方案：可以分流不同服务提供商的服务，分流不同类型的服务，服务隔离化来减少服务相互之间影响以及服务提供商之间的影响。

         当前SIP的前端是通过硬件F5作负载均衡，因此是无状态无差别的服务负载，这也使得无法区分不同的服务提供商的服务请求和不同类型的服务请求，导致服务提供商之间的服务会产生相互影响（旺旺即时通信类API在峰值占用了大部分的服务处理资源，淘宝宝贝上传类API占用了大量的带宽）。近期还有更大的两类API将会接入，因此寻找一个服务可分流的方案势在必行。（当然过去也考虑通过三级域名配置在负载均衡上来解决这些问题，但是这样首先对于开发者来说不透明，其次也是一种比较僵化的设计方案，扩展和维护也有一定的难度）

         在过去也尝试过Apache等Web容器自己的一些load balance特性，当然效果不是很好，和硬件基本无法比拟，而一些专有的“软”负载均衡方案和开源项目也没有深入的去了解，因此借着这次机会，好好深入的挖一挖“软”负载均衡。

                           -------------------
                                 HAProxy
                           Architecture  Guide
                           -------------------
                             version 1.1.34
                              willy tarreau
                               2006/01/29

Version 1.0
Author: Falko Timme <ft [at] falkotimme [dot] com>
Last edited 05/15/2009

This article explains how to set up a two-node load balancer in an active/passive configuration with HAProxy and heartbeat on Debian Lenny. The load balancer sits between the user and two (or more) backend Apache web servers that hold the same content. Not only does the load balancer distribute the requests to the two backend Apache servers, it also checks the health of the backend servers. If one of them is down, all requests will automatically be redirected to the remaining backend server. In addition to that, the two load balancer nodes monitor each other using heartbeat, and if the master fails, the slave becomes the master, which means the users will not notice any disruption of the service. HAProxy is session-aware, which means you can use it with any web application that makes use of sessions (such as forums, shopping carts, etc.).

This example will guide you through a simple IP based load balancing solution that handles ssl traffic.

It appears this configuration wasn’t working with HAProxy version 1.3.20 due to the “option nolinger” feature. I have removed it from the configuration and can confirm it works well with HAProxy v.1.3.15 to v.1.3.20. Because of this, you’ll also notice a significant increase in TIME_WAIT sessions, as well as ip_conntrack_count increasing from ~150 to ~925.