负载均衡（LVS+Keepalived实现高可用集群）

操作系统平台：CentOS5.2
软件：LVS+keepalived

LVS+Keepalived 介绍

LVS

LVS是Linux Virtual Server的简写，意即Linux虚拟服务器，是一个虚拟的服务器集群系统。本项目在1998年5月由章文嵩博士成立，是中国国内最早出现的自由软件项目之一。目前有三种IP负载均衡技术（VS/NAT、VS/TUN和VS/DR）；
十种调度算法（rrr|wrr|lc|wlc|lblc|lblcr|dh|sh|sed|nq）。
Keepalvied
Keepalived在这里主要用作RealServer的健康状态检查以及LoadBalance主机和BackUP主机之间failover的实现

IP配置信息:
LVS-DR-Master 192.168.2.166
LVS-DR-BACKUP 192.168.2.167
LVS-DR-VIP 192.168.2.170
WEB1-Realserver 192.168.2.171
WEB2-Realserver 192.168.2.172
GateWay 192.168.2.253
安装LVS和Keepalvied软件包

1. 下载相关软件包
#mkdir /usr/local/src/lvs
#cd /usr/local/src/lvs
#wget
http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
#wget
http://www.keepalived.org/software/keepalived-1.1.15.tar.gz

2. 安装LVS和Keepalived
#lsmod |grep ip_vs
#uname -r
2.6.18-53.el5PAE
#ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686/ /usr/src/linux

#tar zxvf ipvsadm-1.24.tar.gz
#cd ipvsadm-1.24
#make && make install
#find / -name ipvsadm # 查看ipvsadm的位置

#tar zxvf keepalived-1.1.15.tar.gz
#cd keepalived-1.1.15
#./configure && make && make install
#find / -name keepalived # 查看keepalived位置

#cp /usr/local/etc/rc.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|stop #做成系统启动服务方便管理.
四. 配置LVS实现负载均衡

1． LVS-DR，配置LVS脚本实现负载均衡

vi /usr/local/sbin/lvs-dr.sh

#!/bin/bash
# description: start LVS of DirectorServer
#Written by :NetSeek
http://www.linuxtone.org
GW=192.168.2.253

# website director vip.
WEB_VIP=192.168.2.170
WEB_RIP1=192.168.2.171
WEB_RIP2=192.168.2.172
. /etc/rc.d/init.d/functions

logger $0 called with $1

case "$1" in

start)
# Clear all iptables rules.
/sbin/iptables -F
# Reset iptables counters.
/sbin/iptables -Z
# Clear all ipvsadm rules/services.
/sbin/ipvsadm -C

#set lvs vip for dr
/sbin/ipvsadm --set 30 5 60
/sbin/ifconfig eth0:0 $WEB_VIP broadcast $WEB_VIP netmask 255.255.255.255 up
/sbin/route add -host $WEB_VIP dev eth0:0
/sbin/ipvsadm -A -t $WEB_VIP:80 -s wrr -p 3
/sbin/ipvsadm -a -t $WEB_VIP:80 -r $WEB_RIP1:80 -g -w 1
/sbin/ipvsadm -a -t $WEB_VIP:80 -r $WEB_RIP2:80 -g -w 1
touch /var/lock/subsys/ipvsadm >/dev/null 2>&1

# set Arp
/sbin/arping -I eth0 -c 5 -s $WEB_VIP $GW >/dev/null 2>&1
;;
stop)
/sbin/ipvsadm -C
/sbin/ipvsadm -Z
ifconfig eth0:0 down
route del $WEB_VIP >/dev/null 2>&1
rm -rf /var/lock/subsys/ipvsadm >/dev/null 2>&1
/sbin/arping -I eth0 -c 5 -s $WEB_VIP $GW
echo "ipvsadm stoped"
;;

status)

if [ ! -e /var/lock/subsys/ipvsadm ];then
echo "ipvsadm is stoped"
exit 1
else
ipvsadm -ln
echo "..........ipvsadm is OK."
fi
;;

*)
echo "Usage: $0 {start|stop|status}"
exit 1
esac

exit 0
2． 配置Realserver脚本.

#!/bin/bash
# Written by NetSeek
# description: Config realserver lo and apply noarp
WEB_VIP=192.168.2.170

. /etc/rc.d/init.d/functions

case "$1" in
start)
ifconfig lo:0 $WEB_VIP netmask 255.255.255.255 broadcast $WEB_VIP
/sbin/route add -host $WEB_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"

;;
stop)
ifconfig lo:0 down
route del $WEB_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"
;;
status)
# Status of LVS-DR real server.
islothere=`/sbin/ifconfig lo:0 | grep $WEB_VIP`
isrothere=`netstat -rn | grep "lo:0" | grep $web_VIP`
if [ ! "$islothere" -o ! "isrothere" ];then
# Either the route or the lo:0 device
# not found.
echo "LVS-DR real server Stopped."
else
echo "LVS-DR Running."
fi
;;
*)
# Invalid entry.
echo "$0: Usage: $0 {start|status|stop}"
exit 1
;;
esac
exit 0

附上realserver机上的/etc/sysctl.conf：

# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and
# sysctl.conf(5) for more details.
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
# Controls source route verification
net.ipv4.conf.default.rp_filter = 1
# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0
# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0
# Controls whether core dumps will append the PID to the core filename.
# Useful for debugging multi-threaded applications.
kernel.core_uses_pid = 1
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
或者采用secondary ip address方式配置
# vi /etc/sysctl.conf

添加以下内容如上所示：

net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
#sysctl �Cp
#ip addr add 61.164.122.8/32 dev lo
#ip add list 查看是否绑定
3. 启动lvs-dr脚本和realserver启本，在DR上可以查看LVS当前状态:
#watch ipvsadm �Cln

五．利用Keepalvied实现负载均衡和和高可用性

1.配置在主负载均衡服务器上配置keepalived.conf
#vi /etc/keepalived/keepalived.conf (主调度器)
! Configuration File for keepalived
global_defs {
notification_email {

[email protected]

[email protected]

[email protected]
}
notification_email_from
[email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.2.170
}
}
virtual_server 192.168.2.170 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 60
protocol TCP

real_server 192.168.2.171 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.2.172 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}

在备用调度器上：
#vi /etc/keepalived/keepalived.conf (备用调度器)
! Configuration File for keepalived
global_defs {
notification_email {

[email protected]

[email protected]

[email protected]
}
notification_email_from
[email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.2.170
}
}
virtual_server 192.168.2.170 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 60
protocol TCP

real_server 192.168.2.171 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.2.172 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}

2. 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. vi /etc/rc.local
#/usr/local/sbin/lvs-dr.sh 将lvs-dr.sh这个脚本注释掉。
#/usr/local/sbin/lvs-dr.sh stop 停止lvs-dr脚本
#/etc/init.d/keepalived start 启动keepalived 服务，keepalived就能利用keepalived.conf 配
置文件，实现负载均衡和高可用.
4. 查看lvs服务是否正常

#watch ipvsadm �Cln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddressort Scheduler Flags
-> RemoteAddressort Forward Weight ActiveConn InActConn
TCP 61.164.122.8:80 wrr persistent 60
-> 61.164.122.10:80 Route 3 0 0
-> 61.164.122.9:80 Route 3 0 0
复制代码
#tail �Cf /var/log/message 监听日志，查看状态，测试LVS负载均衡及高可用性是否有效。
5．停Master服务器的keepalived服务，查看BAKCUP服务器是否能正常接管服务。
四．相关参考
1．LVS 基础知识汇总
LVS的算法介绍
http://www.linuxtone.org/viewthread.php?tid=69
学习LVS的三种转发模式
http://www.linuxtone.org/viewthread.php?tid=77
LVS中的IP负载均衡技术
http://www.linuxtone.org/viewthread.php?tid=68
更多的请到
http://www.linuxtone.org
负载均衡版查看
Keepalived 相关参考资料。