keepalived双机热备原理及实例部署LVS+keepalived
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eth1122.126.152.183
内网接口eth0192.168.1.1
lvs_1.test.cometh0192.168.1.5
eth0 VIP192.168.1.2
lvs_2.test.cometh0192.168.1.6
eth0 VIP192.168.1.2
web1.test.cometh0192.168.1.7
lo:0 VIP192.168.1.2
web1.test.cometh0192.168.1.8
lo:0 VIP192.168.1.2
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:0DEVICE=lo:0BOOTPROTO=staticIPADDR=192.168.1.2NETMASK=255.255.255.255GATEWAY=192.168.1.1ONBOOT=yes
修改ARP参数vim /etc/sysctl.confnet.ipv4.conf.eth0.arp_ignore = 1net.ipv4.conf.eth0.arp_announce = 2net.ipv4.conf.all.arp_ignore = 1net.ipv4.conf.all.arp_announce = 2
执行 sysctl -pservice network restartiptables -Fiptables -Xservice iptables savesetenforce 0sed -i s/enforcing/disabled/g /etc/sysconfig/selinuxyum install -y httpdecho "web1192.168.1.7" > /var/www/html/index.htmlservice httpd restartchkconfig httpd onweb2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-eth0DEVICE=eth0BOOTPROTO=staticIPADDR=192.168.1.5NETMASK=255.255.255.0GATEWAY=192.168.1.1ONBOOT=yesTYPE=Ethernet
service network restart安装部署keepalived ipvsadmyum install -y gcc openssl-devel popt-devel libnl libnl-devel kernel-devel ipvsadm下载keepalivedwget 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/./configuremake && make installln -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.confglobal_defs { notification_email {
test@163.com
}
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 startchkconfig keepalived onip addr show #查看虚拟ipipvsadm -Ln #查看lvs规则iptables -Fiptables -Xservice iptables savesetenforce 0sed -i s/enforcing/disabled/g /etc/sysconfig/selinuxlvs_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-eth0DEVICE=eth0BOOTPROTO=staticIPADDR=192.168.1.1NETMASK=255.255.255.0ONBOOT=yes
DNS=8.8.8.8vim /etc/sysconfig/network-scripts/ifcfg-eth1DEVICE=eth1BOOTPROTO=staticIPADDR=122.126.152.183NETMASK=255.255.255.254ONBOOT=yes
DNS=8.8.8.8
service network restartiptables -Fiptables -Xiptables -t nat -Fiptables -t nat -Xiptables -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 122.126.152.183service iptables savesetenforce 0sed -i s/enforcing/disabled/g /etc/sysconfig/selinuxvim /etc/sysctl.confnet.ipv4..ip_forward = 1sysctl -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
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