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 –p

#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 –ln

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 –ln

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 –f /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。

 

http://www.keepalived.org/documentation.html