LVS+Keepalived 高可用性负载均衡自动化配置

前言* 随着互联网飞速的发展，互联网WEB服务器，必须要保证每天7x24x365不间断服务，随着人数不断的增加，有什么好的WEB前端架构呢？既能实现高可用、负载均衡、成本有最低廉呢？答案有木有呢？LVS+Keepalived是一个非常不错的前端均衡选择。（今天来研究一下如何快速配置LVS及日常的维护，供参考！）

一、系统环境

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LVS-Master  192.168 . 2.108 LVS-BACKUP  192.168 . 2.109 LVS-DR-VIP  192.168 . 2.100 WEB1-Realserver  192.168 . 2.79 WEB2-Realserver  192.168 . 2.80

二、Keepalived安装

由于我们使用的是lvs+keepalived，所以这里不需要配置lvs-dr脚本，直接在keepalived.conf里面配置即可！

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#!/bin/sh ###脚本编写目的:自动安装lvs+keepalived ###编写时间:  2011 年 7 月 6 日 17 : 25 : 39 ###初稿人:wugk ###定义变量 DIR1=/usr/src DIR2=/usr/local cat << EOF ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++Welcome to  use  Linux installed a key LVS+KEEPALIVED shells scripts +++++++++++++++++++++*************************++++++++++++++++++++++++ EOF if [ $UID -ne  0  ];then echo “This script must  use  root user ,please exit……” sleep  2 exit  0 fi download () { cd $DIR1 && wget -c http: //www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz http://www.keepalived.org/software/keepalived-1.1.15.tar.gz if [ $? =  0  ];then echo  "Download LVS Code is OK!" else echo  "Download LVS Code is failed,Please check!" exit  1 fi } ipvsadm_install () { ln -s $DIR1/kernels/ 2.6 .* $DIR1/linux cd $DIR1 && tar xzvf ipvsadm- 1.24 .tar.gz &&cd ipvsadm- 1.24  && make && make install if [ $? -eq  0  ];then echo  "Install ipvsadm success,please waiting install keepalived ..............." else echo  "Install ipvsadm failed ,please check !" exit  1 fi } keepalived_install () { cd $DIR1 && tar -xzvf keepalived- 1.1 . 15 .tar.gz &&cd keepalived- 1.1 . 15  && ./configure && make && make install if [ $? -eq  0  ];then echo  "Install keepalived success,please waiting configure keepalived ..............." else echo  "Install keepalived failed ,please check install version !" exit  1 fi } ######如果以上软件包编译报错的话，请检查相关的版本跟系统版本之间的关系，然后手动下载安装. keepalived_config () { cp $DIR2/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/ && cp $DIR2/etc/sysconfig/keepalived /etc/sysconfig/ && mkdir -p /etc/keepalived &&cp $DIR2/etc/keepalived/keepalived.conf /etc/keepalived/ && cp $DIR2/sbin/keepalived /usr/sbin/ if [ $? -eq  0  ];then echo  "Keepalived system server config success!" else echo  "Keepalived system server config failed ,please check keepalived!" exit  1 fi } PS3= "Please select Install Linux Packages:" select option  in  download ipvsadm_install keepalived_install keepalived_config do $option done

以上脚本分别在lvs-master和lvs-backup上执行安装。

三、Keepalived配置

也可以参考配置： http://chinaapp.sinaapp.com/download/keepalived.conf  可以直接打开

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! Configuration Filefor keepalived global_defs {    notification_email {     wgkgood@ 163 .com    }    notification_email_from wgkgood@ 163 .com    smtp_server  127.0 . 0.1    smtp_connect_timeout  30    router_id LVS_DEVEL } # VIP1 vrrp_instance VI_1 {    state MASTER    interface  eth0    lvs_sync_daemon_inteface eth0    virtual_router_id  51    priority  100    advert_int  5    authentication {      auth_type PASS      auth_pass  1111    }    virtual_ipaddress {      192.168 . 2.100    } } #REAL_SERVER_1 virtual_server  192.168 . 2.100  80  {    delay_loop  6    lb_algo wlc    lb_kind DR    persistence_timeout  60    protocol TCP    real_server  192.168 . 2.79  80  {      weight  100      TCP_CHECK {      connect_timeout  10      nb_get_retry  3      delay_before_retry  3      connect_port  80      } } #REAL_SERVER_2    real_server  192.168 . 2.80  80  {      weight  100      TCP_CHECK {      connect_timeout  10      nb_get_retry  3      delay_before_retry  3      connect_port  80      }    } }

注意***Lvs-backup端同样配置，只需要更改state MASTER为state BACKUP，修改priority 100为priority 90即可。

四、WEB服务端配置

如下的VIP1指的是lvs-dr-vip地址，及对外提供访问的虚拟ip：

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#!/bin/sh PS3= "Please Choose whether or not to start a realserver VIP1 configuration:" select i  in "start" "stop" do case "$i" in start) read -p  "Please enter the virtual server IP address:"  VIP1 ifconfig lo: 0  $VIP1 netmask  255.255 . 255.255  broadcast $VIP1 /sbin/route add -host $VIP1 dev lo: 0 echo  "1"  >/proc/sys/net/ipv4/conf/lo/arp_ignore echo  "2"  >/proc/sys/net/ipv4/conf/lo/arp_announce echo  "1"  >/proc/sys/net/ipv4/conf/all/arp_ignore echo  "2"  >/proc/sys/net/ipv4/conf/all/arp_announce sysctl -p >/dev/ null  2 >& 1 echo  "RealServer Start OK" exit  0 ;; stop) ifconfig lo: 0  down route del $VIP1 >/dev/ null  2 >& 1 echo  "0"  >/proc/sys/net/ipv4/conf/lo/arp_ignore echo  "0"  >/proc/sys/net/ipv4/conf/lo/arp_announce echo  "0"  >/proc/sys/net/ipv4/conf/all/arp_ignore echo  "0"  >/proc/sys/net/ipv4/conf/all/arp_announce echo  "RealServer Stoped" exit  1 ;; *) echo  "Usage: $0 {start|stop}" exit  2 esac done

脚本会提示是否启动，按1即启动，然后输入vip地址 192.168.2.100 ，用ifconfig你会看到：lo:0的ip即表示配置ip成功。

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lo: 0   Link encap:Local Loopback     inet addr: 192.168 . 2.100  Mask: 255.255 . 255.255     UP LOOPBACK RUNNING MTU: 16436  Metric: 1

五、测试LVS+keepalived

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/etc/init.d/keepalived restart 查看lvs-master日志： 在浏览器里面访问 http: //192.168.2.100/ 即可！当你宕掉lvs-master后，lvs-backup会接管变成lvs-master提供服务，当lvs-master故障恢复后，lvs-backup又会变成原来的状态！ 所安装的脚本可以在这里下载： 在lvs-master和lvs-backup上执行http: //chinaapp.sinaapp.com/download/lvs-keepalived.sh 在web服务器端执行http: //chinaapp.sinaapp.com/download/realserver.sh

六、实战建议

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为了解决脑裂问题，需要把主MASTER和备BACKUP各自的keepalived.conf配置文件里面的state 状态都改成BACKUP，优先级分别设置 100 和 90 。 我们常听说脑裂问题，到底什么是脑裂问题呢？ 在集群配置中的split-brain现象是指，主从之间互相检测不到心跳，同时抢占资源，导致 服务无法正常访问的情况。所以我们还需要在主备keepalived.conf添加nopreempt 指令！

附realserver.sh脚本文件：

本文转自 wgkgood 51CTO博客，原文链接:http://blog.51cto.com/wgkgood/605322