Linux下lvs通过keepalived实现负载均衡

1.安装ipvsadm：（注意支持的系统内核版本号，新的版本只支持2.6.2*以上的系统内核，我选择的是1.24这个版本）
http://www.linuxvirtualserver.org/software/ipvs.html
1.1创建linux内核链接

# rpm -ivh /usr/src/kernels/2.6.18-238.el5-x86_64

# ln -s /usr/src/kernels/2.6.18-238.el5-x86_64 /usr/src/linux

1.2安装 ipvsadm

# cd ipvsadm-1.24

# make

# make install

2.安装keepalived
http://www.keepalived.org/download.html
安装keepalived的1.2以上的版本必须指定内核位置（我的CentOs5.6选择的是1.1.19这个版本）

# ./configure --prefix=/usr/local/keepalived (1.2以上需指定--with-kernel-dir=/usr/src/kernels/2.6.18-238.el5-x86_64)

# make

# make install

3.配置keepalived.conf(需要生成md5加密值)

#/usr/local/keepalived/bin/genhash -s 192.168.152.146 -p 80 -u /lived.jsp

生成后的文档，见keepalived.conf

#
#guration File for keepalived
#global define
global_defs {
router_id LVS_WEB_1
}

vrrp_sync_group VGM {
group {
VI_WEB
}
}

################################################################
#      vvrp_instance  define                                   #
################################################################
vrrp_instance VI_WEB {
state MASTER
interface eth0
lvs_sync_daemon_inteface eth0
virtual_router_id 51
priority 180
advert_int 3
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.152.222
}
}

##############################################################
#   virtual machine  setting                                 #
##############################################################

# setting port 80 forward
virtual_server 192.168.152.222 80 {
delay_loop 6
lb_algo wlc
lb_kind DR
persistence_timeout 60
protocol TCP

real_server 192.168.152.146 80 {
weight 100
#            TCP_CHECK {
HTTP_GET {
url {
path /lived.jsp
digest 449089bf261dd8b34c786d0aaa8d80b6
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.152.153 80 {
weight 100
#            TCP_CHECK {
HTTP_GET {
url {
path /lived.jsp
digest 449089bf261dd8b34c786d0aaa8d80b6
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}

4.开启负载服务器路由机制

#vi /etc/sysctl.conf

使 net.ipv4.ip_forward = 1

然后使其生效，执行

# sysctl -p

5. web机器上的客户端启动脚本

vi /sbin/lvs_realserver.sh

#!/bin/bash
VIP1=192.168.152.222
#VIP2=2.3.4.5
. /etc/rc.d/init.d/functions
case "$1" in
start)
echo "start LVS of RealServer DR"
/sbin/ifconfig lo:0 $VIP1 broadcast $VIP1 netmask 255.255.255.255 up
#          /sbin/ifconfig eth0:1 $VIP2 broadcast $VIP2 netmask 255.255.255.255 up
/sbin/route add -host $VIP1 dev lo:0            ###VIP绑定至回环接口上
#          /sbin/route add -host $VIP2 dev eth0:1
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore   ###抑制arp广播
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce      ###抑制arp广播
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
;;
stop)
/sbin/ifconfig lo:0 down
#           /sbin/ifconfig eth0:1 down
echo "close LVS of RealServer DR"
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 "Usage: $0 {start|stop}"
exit 1
esac
exit 0

保存退出

#chmod 775 /sbin/lvs_realserver.sh

从centos6开始，内核进行了内核源地址验证，所以需要再对内核进行如下配置。

echo "0" > /proc/sys/net/ipv4/conf/lo/rp_filter

echo "1" > /proc/sys/net/ipv4/conf/em1/rp_filter

echo "1" > /proc/sys/net/ipv4/conf/em2/rp_filter

echo "0" > /proc/sys/net/ipv4/conf/all/rp_filter

6. 执行测试

# /sbin/lvs_server.sh start

查看ifconfig是否有ifcfg-lo:0(有就对了）

查看route -n 路由表是否多了lo:0路由（有就对了）

# /sbin/lvs_server.sh stop

查看ifconfig是否有ifcfg-lo:0 (无就对了）

查看route -n 路由表是否多了lo:0路由（无就对了）

# /sbin/lvs_server.sh adsa

是否提示参数错误，只能使用{start|stop}

7.启动keepalived

# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived

# chmod +x /etc/init.d/keepalived

# vi /etc/init.d/keepalived

. /etc/sysconfig/keepalived修改为：

. /usr/local/keepalived/etc/sysconfig/keepalived 即指向正确的文件位置

并添加：如下内容

PATH="$PATH:/usr/local/keepalived/sbin"

export PATH

#vi /usr/local/keepalived/etc/sysconfig/keepalived

KEEPALIVED_OPTIONS="-D -f /usr/local/keepalived/etc/keepalived/keepalived.conf"

service keepalived restart

chkconfig keepalived on

第二种启动方式：启动命令加上指定配置文件的位置

/usr/local/keepalived/sbin/keepalived -D -f /usr/local/keepalived/etc/keepalived/keepalived.conf

8.负载均衡器集群的设置

拷贝keepalived.conf到其他BACKUP集群上，然后修改如下三个参数

router_id LVS_WEB_2

state BACKUP

priority 150

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lvs服务器查看keepalived进程： ps aux|grep keepalived

lvs服务器查看ipvsadm转发情况： ipvsadm

lvs服务器查看整体信息： cat /var/log/messages

关于监控可以使用nagios全面监控代替全局变量中的设置email报警邮箱

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