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

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！

#!/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

! Configuration Filefor keepalived
global_defs {
  notification_email {
   [email protected]
  }
  notification_email_from [email protected]
  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：

#!/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。

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

/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

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：

#!/bin/sh
#LVS Client Server
VIP=192.168.111.138
case  $1  in
                                                                                                                                                                                                                                                         
start)
                                                                                                                                                                                                                                                         
    ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
    /sbin/route add -host $VIP 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 $VIP >/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 OK"
    exit 1
;;
*)
    echo "Usage: $0 {start|stop}"
;;
esac