LVS+KEEPALIVED实现WEB服务器80端口的负载均衡

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）本文是按照VS/DR的方式配置,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

部署环境：

系统：linux centos 5.8

浮动IP：192.168.1.150

主LVS IP：192.168.1.86

备LVS IP：192.168.1.87

真实服务器WEB1 IP：192.168.1.88

真实服务器WEB2 IP：192.168.1.250

安装与配置步骤

1.主备LVS下载软件包

#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.主备LVS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

(执行ln -s 出错请看最后的常见问题处理)

#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

3.主备LVS配置Keepalived
修改配置文件/etc/keepalived/keepalived.conf为如下内容（注意真实环境下将#注释说明的内容去掉）

			
							1
						
							global_defs {
					
							2
						
							notification_email {
					
							3
						
							admin@gmail.com
					
							4
						
							}
					
							5
						
							notification_email_from sns-lvs@gmail.com
					
							6
						
							smtp_server 127.0.0.1
					
							7
						
							router_id LVS_DEVEL
					
							8
						
							}
					
							9
						
							10
						
							vrrp_instance VI_1 {
					
							11
						
							state MASTER   #备份服务器上将MASTER改为BACKUP    
					
							12
						
							interface eth0
					
							13
						
							virtual_router_id 88
					
							14
						
							priority 100  # 备份服务上将100改为99
					
							15
						
							advert_int 1
					
							16
						
							authentication {
					
							17
						
							auth_type PASS
					
							18
						
							auth_pass 123123
					
							19
						
							}
					
							20
						
							virtual_ipaddress {
					
							21
						
							192.168.1.150
					
							22
						
							#(如果有多个VIP，继续换行填写.)
					
							23
						
							}
					
							24
						
							}
					
							25
						
							26
						
							virtual_server 192.168.1.150 80 {
					
							27
						
							delay_loop 3 #(每隔3秒查询realserver状态)
					
							28
						
							lb_algo wrr #(lvs 算法)
					
							29
						
							lb_kind DR #(Direct Route)
					
							30
						
							persistence_timeout 3 #(同一IP的连接3秒内被分配到同一台realserver)
					
							31
						
							protocol TCP #(用TCP协议检查realserver状态)
					
							32
						
							33
						
							real_server 192.168.1.88 80 {
					
							34
						
							weight 3  #(权重)
					
							35
						
							TCP_CHECK {
					
							36
						
							connect_timeout 10 #(10秒无响应超时)
					
							37
						
							nb_get_retry 3
					
							38
						
							delay_before_retry 3
					
							39
						
							connect_port 80
					
							40
						
							}
					
							41
						
							}
					
							42
						
							43
						
							real_server 192.168.1.250 80 {
					
							44
						
							weight 3
					
							45
						
							TCP_CHECK {
					
							46
						
							connect_timeout 10
					
							47
						
							nb_get_retry 3
					
							48
						
							delay_before_retry 3
					
							49
						
							connect_port 80
					
							50
						
							}
					
							51
						
							}
					
							52
						
							}

4.配置提供真实服务的主机
添加配置文件/etc/realserver/realserver.sh为以下内容

#!/bin/bash

			
							1
						
							SNS_VIP=192.168.1.150
					
							2
						
							3
						
							/etc/rc.d/init.d/functions
					
							4
						
							5
						
							case "$1" in
					
							6
						
							start)
					
							7
						
							/sbin/ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP up
					
							8
						
							/sbin/route add -host $SNS_VIP dev lo:0
					
							9
						
							echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
					
							10
						
							echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
					
							11
						
							echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
					
							12
						
							echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
					
							13
						
							sysctl -p >/dev/null 2>&1
					
							14
						
							echo "RealServer Start OK"
					
							15
						
							;;
					
							16
						
							17
						
							stop)
					
							18
						
							/sbin/ifconfig lo:0 down
					
							19
						
							/sbin/route del $SNS_VIP >/dev/null 2>&1
					
							20
						
							echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
					
							21
						
							echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
					
							22
						
							echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
					
							23
						
							echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
					
							24
						
							echo "RealServer Stoped"
					
							25
						
							;;
					
							26
						
							27
						
							*)
					
							28
						
							echo "Usage: $0 {start|stop}"
					
							29
						
							exit 1
					
							30
						
							esac
					
							31
						
							32
						
							exit 0

5.提供真实服务的主机修改/etc/rc.d/rc.loal

#vi /etc/rc.d/rc.local

添加
/etc/realserver/realserver.sh

6.主备LVS执行

#chkconfig --level keepalived 35 on

7.主备LVS启动keepalived服务

#/etc/init.d/keepalived start

8.提供真实服务的主机运行/etc/realserver/realserver.sh

#chmod +x /etc/realserver/realserver.sh

#/etc/realserver/realserver.sh

9.查看当前LVS的状态

#ipvsadm -ln

常见问题处理：

1.安装时发现没有目录：/usr/src/kernels，安装kernel-devel包可以解决

#yum install kernel-devel

2.安装编译keeepalived时需要支持LVS时才可以做LVS调度：
例如出现下面情况，将不支持lvs
Keepalived configuration
------------------------
Keepalived version : 1.1.15
Compiler : gcc
Compiler flags : -g -O2
Extra Lib : -lpopt -lssl -lcrypto
Use IPVS Framework : No
IPVS sync daemon support : No
Use VRRP Framework : Yes
Use LinkWatch : No
Use Debug flags : No
解决办法，指定kernel目录：
/configure --with-kernel-dir=/usr/src/kernels/2.6.9-55.EL-i686 （rhel4.5_32平台）
./configure --with-kernel-dir=/usr/src/kernels/2.6.18-164.el5-i686/（rhel5.4_32平台）

正确情况：
Keepalived configuration
------------------------
Keepalived version : 1.1.15
Compiler : gcc
Compiler flags : -g -O2
Extra Lib : -lpopt -lssl -lcrypto
Use IPVS Framework : Yes
IPVS sync daemon support : Yes
Use VRRP Framework : Yes
Use LinkWatch : No
Use Debug flags : No
然后在make，make install

3.安装编译keeepalived时
configure: error:
!!! OpenSSL is not properly installed on your system. !!!
!!! Can not include OpenSSL headers files. !!!

#yum install e2fsprogs-devel keyutils-libs-devel libsepol-devel libselinux-devel krb5-devel zlib-devel openssl-devel

参考资料：
http://i-david.iteye.com/blog/1684342
官方文档：
http://www.keepalived.org/documentation.html

(责任编辑：IT)

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LVS+KEEPALIVED实现WEB服务器80端口的负载均衡