lvs+keepalived实现高可用负载均衡集群
一、LVS+Keepalived介绍
1. 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）；八种调度算法（rr,wrr,lc,wlc,lblc,lblcr,dh,sh）。
2. 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。
二、网站负载均衡拓朴图
+---------------------------------VIP（192.168.1.222）---------------------------------+
| | |
| | |
server（MASTER）<--------------------keepalived------------------->server（BACKUP）
192.168.1.202 192.168.1.204
IP规划：
| Hostname | IP |
| VIP | 192.168.1.222 |
| MASTER | 192.168.1.202 |
| BACKUP | 192.168.1.204 |
| REALSERVER1 | 192.168.1.203 |
| REALSERVER2 | 192.168.1.201 |
三、部署步骤
安装LVS和Keepalived软件包
1. 下载相关软件包
mkdir /usr/local/src/lvs
cd /usr/local/src/lvs
wget http://down1.chinaunix.net/distfiles/ipvsadm-1.24.tar.gz
wget http://www.keepalived.org/software/keepalived-1.2.19.tar.gz
2. 安装LVS和Keepalived
lsmod |grep ip_vs #显示已载入系统的ip_vs模块
uname -r #显示操作系统的发行版号
2.6.32-279.el6.x86_64 #操作系统的发行版号
yum install kernel-devel #安装与系统内核配套的开发包
yum -y install popt*
yum -y install libnl*
yum -y install openssl*
ln -s /usr/src/kernels/2.6.32-279.9.1.el6.x86_64/ /usr/src/linux #建立软连接
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.
3. 配置realserver脚本
在192.168.203（realserver）上配置，脚本我保存在了/opt下
#!/bin/bash
#description Config LVS to realserver lo and apply noarp
#Written by ce
VIP=192.168.1.222
. /etc/init.d/functions
case "$1" in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP
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
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"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
chmod a+x /opt/realserver.sh #赋予可执行权限
/opt/realserver.sh start #启动
之后，通过rsync远程备份到192.168.1.201（另一台realserver上）
rsync -av /opt/realserver.sh [email protected]:/root/
然后，在192.168.1.201上启动realserver脚本。
4. 利用keepalived实现负载均衡和高可用性
1. 配置在主负载均衡服务器(192.168.1.202)上配置keepalived.conf
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
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 {
192.168.1.222
}
}
virtual_server 192.168.1.222 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 60
protocol TCP
real_server 192.168.1.203 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.1.201 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
2. 配置在备份负载均衡服务器(192.168.1.204)上配置keepalived.conf
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
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 {
192.168.1.222
}
}
virtual_server 192.168.1.222 80 {
delay_loop 6
lb_algo wrr
lb_kind DR
persistence_timeout 60
protocol TCP
real_server 192.168.1.203 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.1.201 80 {
weight 3
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
3. 启动keepalived
/etc/init.d/keepalived start（或者service 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！
4. 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 192.168.1.200:80 wrr persistent 60
-> 192.168.1.203:80 Route 3 0
-> 192.168.1.201:80 Route 3 0
tail –f /var/log/message 监听日志，查看状态。