架构基于WEB的负载均衡Nginx+keepalived

1、Nginx+keepalived架构基于WEB的负载均衡（转载）服务器故障：(服务器故障包括：服务器宕机、web服务终止、网线松动等等)当lvs-master故障时，无法再接受用户请求并将请求转发给真实的web服务器(即便真实web服务器正常)从而导致整个web服务的瘫痪，也就是lvs控制器存在单点故障问题。当lvs-master正常时，真实地web服务器如web1-realserver故障。此时lvs-master并不知道真实服务器是否在正常提供web服务，所以仍然在向故障的web1-realserver转发用户请求。这样的结果是用户请求无法被故障web服务器相应，某些用户可以访问网站有些则

2、无法访问。基于以上的问题，我们需要想办法实现对lvs控制器和web服务器的健康监测,一旦服务出现问题能保证服务不中断的情况下排除故障。即增加lvs控制器实现主备模式避免单点故障以及自动删除故障web服务结点并当它恢复后再自动添加到群集中这样的功能，这就是LVS+keepalived能实现的功能。整个线上环境由Linuxtone的站长netseek提供，这里表示感谢，整个系统的拓补如下：名称IPLVS-DR-MasterLVS-DR-BACKUPLVS-DR-VIPWEB1-RealserverWEB

3、2-Realserver0实施步骤：在realserver主机上实行脚本realserver,为lo:0绑定VIP地址，这步分别在二个web主机上、0实施。这步提前做，是因为以后的过程中这一步是不会发生更改的。#vim /usr/local/sbin/realserver#!/bin/bashSNS_VIP=. /etc/rc.d/init.d/functionscase $1 instart)ifconfig lo:0 $SNS_VIP netmask 255.255.25

4、5.255 broadcast $SNS_VIP/sbin/route add -host $SNS_VIP dev lo:0echo 1 /proc/sys/net/ipv4/conf/lo/arp_ignoreecho 2 /proc/sys/net/ipv4/conf/lo/arp_announceecho 1 /proc/sys/net/ipv4/conf/all/arp_ignoreecho 2 /proc/sys/net/ipv4/conf/all/arp_announcesysctl -p /dev/null 2&1echo RealServer Start OK;stop)if

5、config lo:0 downroute del $SNS_VIP /dev/null 2&1echo 0 /proc/sys/net/ipv4/conf/lo/arp_ignoreecho 0 /proc/sys/net/ipv4/conf/lo/arp_announceecho 0 /proc/sys/net/ipv4/conf/all/arp_ignoreecho 0 /proc/sys/net/ipv4/conf/all/arp_announceecho RealServer Stoped;*)echo Usage: $0 start|stopexit 1esacexit 0为二台l

6、vs主机安装lvs脚本，这步并非必要。做完这步时可以检测到用软件实现了LVS/DR的双机互备机制，但并不能实现的智能自动增加删除故障的web站点，所以这个靠keepalived来实现。过程如下：#mkdir /usr/local/src/lvs#cd /usr/local/src/lvs#wget/software/kernel-2.6/ipvsadm-1.24.tar.gz#ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686/ /usr/src/linux#tar zxvf ipvsadm-

7、1.24.tar.gz#cd ipvsadm-1.24#make#make installlvs脚本如下 /usr/local/src/lvs/lvs#!/bin/bash#website director vip.SNS_VIP=SNS_RIP1=SNS_RIP2=0. /etc/rc.d/init.d/functionslogger $0 called with $1case $1 instart)# set squid vip/sbin/ipvsadm -set 30 5 60/sbin/ifconfig eth0:

8、0 $SNS_VIP broadcast $SNS_VIP netmask 55broadcast $SNS_VIP up/sbin/route add -host $SNS_VIP dev eth0:0/sbin/ipvsadm -A -t $SNS_VIP:80 -s wrr -p 3/sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP1:80 -g -w 1/sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP2:80 -g -w 1touch /var/lock/subsys/ipvsadm /

9、dev/null 2&1;stop)/sbin/ipvsadm -C/sbin/ipvsadm -Zifconfig eth0:0 downifconfig eth0:1 downroute del $SNS_VIProute del $SS_VIPrm -rf /var/lock/subsys/ipvsadm /dev/null 2&1echo ipvsadm stoped;status)if ! -e /var/lock/subsys/ipvsadm ;thenecho ipvsadm stopedexit 1elseecho ipvsadm OKfi;*)echo Usage: $0 s

10、tart|stop|statusexit 1esacexit 0关闭lvs脚本./lvs stop，编辑keepalived.conf文件，用keepalived实现负载均衡及高可用性。a)Keepalved的安装#wget/software/keepalived-1.1.15.tar.gz#tar zxvf keepalived-1.1.15.tar.gz#cd keepalived-1.1.15#./configure#make#make install将keepalived做成启动脚务，方便管理:#cp /usr/local/etc/rc.

11、d/init.d/keepalived /etc/rc.d/init.d/#cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/#mkdir /etc/keepalived#cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/#cp /usr/local/sbin/keepalived /usr/sbin/#service keepalived start|stopb)Keealived的配置1、配置在主负载均衡服务器上配置keepalived.conf#vim /et

12、c/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs notification_email notification_email_smtp_server # smtp_connect_timeout 30router_id LVS_DEVELvrrp_instance VI_1 state MASTER#备份服务器上将MASTER改为BACKUPinterface eth0virtual_router_

13、id 51priority 100#备份服务上将100改为99advert_int 1authentication auth_type PASSauth_pass 1111virtual_ipaddress virtual_server 80 delay_loop 6#(每隔10秒查询realserver状态)lb_algo wrr#lvs 算法lb_kind DR#Direct Routepersistence_timeout 60#同一IP的连接60秒内被分配到同一台realserverprotocol TCP#用TCP协议检查realse

14、rver状态real_server 80 weight 3#权重TCP_CHECK connect_timeout 10#10秒无响应超时nb_get_retry 3delay_before_retry 3connect_port 80real_server 0 80 weight 3TCP_CHECK connect_timeout 10nb_get_retry 3delay_before_retry 3connect_port 802、BACKUP服务器同上配置，先安装lvs再按装keepalived,仍后配置/etc/keepalived/keepalived.conf，只需将红色标示的部分改一下即可。3、停掉lvs脚本，分别在二台lvs机上启动servcie keepalived start就可实现负载均衡及高可用集群。值得注意的是：1、你必须向你的服务器所在机房IDC多申请一个IP供VIP使用。2、服务器的iptables、SElinux均关闭，在生产过程中，我