在Linux下使用LVS+keepalived搭建高可用集群
在Linux下使用LVS+keepalived搭建高可用集群一． 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）。
LVS中文支持站点：http://zh.linuxvirtualserver.org/
Keepalived
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.
Keepalived官方站点：http://www.keepalived.org/
二． 实验所用软件环境及拓扑图
实验软件环境：
1. 系统Centos 5.6 x64
2. 软件LVS,Keepalived，Apache
3. 拓扑图如下：
http://blog.运维网.com/attachment/201202/103608569.png
4. IP配置信息
VIP(虚拟IP)： 192.168.1.35
DIP1(主调度器)：192.168.1.31
DIP2(备份调度)：192.1681.32
RIP1(主WEB)：192.168.1.33
RIP2(副WEB)：192.168.1.34
网 关 ：192.168.1.1
三．开始安装LVS+Keepalived
1.下载相关软件包
mkdir /soft //建立一个存放软件的目录
cd/soft
wgethttp://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
wgethttp://www.keepalived.org/software/keepalived-1.1.15.tar.gz
2.安装LVS和Keepalived
lsmod | grep ip_vs //查看内核中是否已经加载ip_vs模块
uname -r //查看当前内核版本号
2.6.18-238.el5 //当前内核版本号
ln -s /usr/src/kernels/2.6.18-238.el5-x86_64//usr/src/linux/ //将内核模块做软连接至/usr/src/目录下 并改名为/usr/src/linux/这样做的好处是，在编译keepalived的时候可以直接找到内核文件，而不用指定内核路径，如果不做此项操作，则在编译时需指定内核路径
tar xvf ipvsadm-1.24.tar.gz
cd ipvsadm-1.24
make && make install
find / -name ipvsadm //查看ipvsadm的位置
tar xvf 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.
3. 配置LVS实现负载均衡
a）LVS-DR，配置LVS脚本实现负载均衡 ,此脚本只为测试LVS是否成功，后面主备切换使用keepalived，此脚本不用。
vi /usr/local/sbin/lvs-dr.sh
#!/bin/bash
# description: start LVS of DirectorServer
#Written by :Supernic
#www.supernic.cn
GW=192.168.2.253
# website director vip.
WEB_VIP=192.168.1.35
WEB_RIP1=192.168.1.33
WEB_RIP2=192.168.1.34
. /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
b）配置RealServer脚本
#!/bin/bash
# Written by Supernic
# description: Config realserver lo and apply noarp
WEB_VIP=192.168.1.35
. /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
或者采用secondary ip address方式配置
vi /etc/sysctl.conf
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 add192.168.1.35/32 dev lo
ip add list \\查看是否绑定
c）启动lvs-dr脚本和RealServer脚本，在DR上可以查看当前状态，（lvs-dr脚本只在测试LVS时使用，后面的调度只用到keepalived就行了，不用此脚本）
watch ipsadm –ln
四． 利用Keepalived实现负载均衡和高可用性
1.在主调度器上配置Keepalived
1. ! Configuration File for keepalived
2.
3. global_defs {
4. notification_email {
5. support@gmail.com
6. }
7. notification_email_from sns-lvs@gmail.com
8. smtp_server 127.0.0.1
9. # smtp_connect_timeout 30
10. router_id LVS_DEVEL
11. }
12.
13. # 20120225 written by :supernic
14. # VIP1
15. vrrp_instance VI_1 {
16. state MASTER #备份服务器上将MASTER改为BACKUP
17. interface eth0
18. virtual_router_id 51
19. priority 100 # 备份服务上将100改为99
20. advert_int 1
21. authentication {
22. auth_type PASS
23. auth_pass 1111
24. }
25. virtual_ipaddress {
26. 192.168.1.35
27. #(如果有多个VIP，继续换行填写.)
28. }
29. }
30.
31. virtual_server 192.168.1.35 80 {
32. delay_loop 6 #(每隔10秒查询realserver状态)
33. lb_algo wrr #(lvs 算法)
34. lb_kind DR #(Direct Route)
35. persistence_timeout 60 #(同一IP的连接60秒内被分配到同一台realserver)
36. protocol TCP #(用TCP协议检查realserver状态)
37.
38. real_server 192.168.1.33 80 {
39. weight 3 #(权重)
40. TCP_CHECK {
41. connect_timeout 10 #(10秒无响应超时)
42. nb_get_retry 3
43. delay_before_retry 3
44. connect_port 80
45. }
46. }
47. real_server 192.168.1.34 80 {
48. weight 3
49. TCP_CHECK {
50. connect_timeout 10
51. nb_get_retry 3
52. delay_before_retry 3
53. connect_port 80
54. }
55. }
56. }
57.
.
2.backup配置同上，只需将state和priority修改即可。
3.停掉lvs-dr脚本，启动keepalived服务
/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.
整个LVS负均衡HA方案，由keepalived.conf一个文件即可搞定！
chkcofig keepalived on //让keepalvied开机自启动
ipvsadm –ln //查看LVS服务是否正常
# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 192.168.1.35:80 wrr persistent 60
-> 192.168.1.33:80 Route 3 0 0
-> 192.168.1.34:80 Route 3 0 0
#
4.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。
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