keepalived简介
它是由C语言编写的路由热备软件，主要提供简单高效的负载均衡及高可用解决方案。keepalived通过VRRP协议实现高可用架构。lvs实现集群分发，keepalived实现调度器的主备方案，两者结合实现集群系统的高负载高可用。
VRRP协议是为了防止单点故障而设计的主从灾备协议，VRRP将两台或者多台路由设备虚拟成一个设备，对外提供一个虚拟路由ip地址，主路由设备处于启用状态时，不断的发送自身信息到备用设备，以表明主路由状态正常，当备用设备收不到主设备的信息时，备用设备会根据自身的优先级选举出新的主设备，并保证提供所有业务功能。
LVS+keepalived实例
服务器名称 网络接口 IP地址
| router | 外网接口eth1 | 122.126.152.183 |
| 内网接口eth0 | 192.168.1.1 | |
| lvs_1.test.com | eth0 | 192.168.1.5 |
| eth0 VIP | 192.168.1.2 | |
| lvs_2.test.com | eth0 | 192.168.1.6 |
| eth0 VIP | 192.168.1.2 | |
| web1.test.com | eth0 | 192.168.1.7 |
| lo:0 VIP | 192.168.1.2 | |
| web1.test.com | eth0 | 192.168.1.8 |
| lo:0 VIP | 192.168.1.2 |
首先安装配置web1和web2
设置web1网路参数及回环设备lo:0设置VIP
vim /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.1.7
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
ONBOOT=yes
vim /etc/sysconfig/network-scripts/ifcfg-lo:0
DEVICE=lo:0
BOOTPROTO=static
IPADDR=192.168.1.2
NETMASK=255.255.255.255
GATEWAY=192.168.1.1
ONBOOT=yes
修改ARP参数
vim /etc/sysctl.conf
net.ipv4.conf.eth0.arp_ignore = 1
net.ipv4.conf.eth0.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
执行 sysctl -p
service network restart
iptables -F
iptables -X
service iptables save
setenforce 0
sed -i s/enforcing/disabled/g /etc/sysconfig/selinux
yum install -y httpd
echo "web1 192.168.1.7" > /var/www/html/index.html
service httpd restart
chkconfig httpd on
web2机器上执行与web1相同步骤，注意修改部分参数
lvs_1调度器操作
首先设置网络
vim /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.1.5
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
ONBOOT=yes
TYPE=Ethernet
service network restart
安装部署keepalived ipvsadm
yum install -y gcc openssl-devel popt-devel libnl libnl-devel kernel-devel ipvsadm
下载keepalived
wget http://www.keepalived.org/software/keepalived-1.3.0.tar.gz
tar zxf keepalived-1.3.0.tar.gz -C /usr/src/
cd /usr/src/keepalived-1.3.0/
./configure
make && make install
ln -s /usr/local/etc/keepalived/ /etc/
ln -s /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/
ln -s /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/sbin/keepalived /usr/sbin/
lvs_1为主设备，lvs_2为从设备，下面修改配置文件
vim /etc/keepalived/keepalived.conf
global_defs {
notification_email {
}
notification_email_from root@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id lvs_1
}
vrrp_instance LVS_HA {
state MASTER #lvs_2为BACKUP
interface eth0
virtual_router_id 60 #lvs_2的VRID必须与lvs-1相同
priority 100 #lvs-2为从设备，必须小于 lvs-1的参数
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.2/24
}
}
virtual_server 192.168.1.2 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
persistence_timeout 50
protocol TCP
real_server 192.168.1.7 80 {
weight 1
TCP_CHECK {
connect_timeout 20
connect_port 80
nb_get_retry 3
}
}
real_server 192.168.1.8 80 {
weight 1
TCP_CHECK {
connect_timeout 20
connect_port 80
nb_get_retry 3
}
}
}
service keepalived start
chkconfig keepalived on
ip addr show #查看虚拟ip
ipvsadm -Ln #查看lvs规则
iptables -F
iptables -X
service iptables save
setenforce 0
sed -i s/enforcing/disabled/g /etc/sysconfig/selinux
lvs_2机器上执行相同操作，注意修改部分参数
下面配置router机器，这里用做软路由，生产环境直接用硬件路由设备
vim /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.1.1
NETMASK=255.255.255.0
ONBOOT=yes
DNS=8.8.8.8
vim /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
BOOTPROTO=static
IPADDR=122.126.152.183
NETMASK=255.255.255.254
ONBOOT=yes
DNS=8.8.8.8
service network restart
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t nat -I PREROUTING -d 122.126.152.183 -p tcp -dport 80 -j DANT --to--destination 192.168.1.2:80
iptables -t nat -I PREROUTING -s 192.168.1.0/24 -p tcp -j SNAT --to-source 122.126.152.183
service iptables save
setenforce 0
sed -i s/enforcing/disabled/g /etc/sysconfig/selinux
vim /etc/sysctl.conf
net.ipv4..ip_forward = 1
sysctl -p
客户端测试
浏览器访问http://122.126.152.183 将得到不同real server的数据包