virtual ipaddress：这里设置的就是VIP，也就是虚拟IP地址，他随着state的变化而增加删除，当state为master的时候就添加，当state为backup的时候删除，这里主要是有优先级来决定的，和state设置的值没有多大关系，这里可以设置多个IP地址；
authentication：这里设置认证；
auth type：认证方式，可以是PASS或AH两种认证方式；
auth pass：认证密码；
启动俩台服务器的keepalived
[root@master ~]# service keepalived start
Starting keepalived: [ OK ]
[root@backup ~]# service keepalived start
Starting keepalived: [ OK ]
[root@master ~]# tail -f /var/log/messages
Jan 10 11:40:56 localhost Keepalived_healthcheckers[19368]: Using LinkWatch kernel netlink reflector...
Jan 10 11:40:56 localhost Keepalived_vrrp[19369]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 10 11:40:56 localhost Keepalived_vrrp[19369]: Configuration is using : 63019 Bytes
Jan 10 11:40:56 localhost Keepalived_vrrp[19369]: Using LinkWatch kernel netlink reflector...
Jan 10 11:40:56 localhost Keepalived_vrrp[19369]: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)]
Jan 10 11:40:57 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 10 11:40:58 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 10 11:40:58 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 10 11:40:58 localhost Keepalived_healthcheckers[19368]: Netlink reflector reports IP 192.168.30.230 added
Jan 10 11:40:58 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
Jan 10 11:41:03 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
Jan 10 11:41:14 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) Received lower prio advert, forcing new election
Jan 10 11:41:14 localhost Keepalived_vrrp[19369]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
[root@master ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:f3:fc:ba brd ff:ff:ff:ff:ff:ff
inet 192.168.30.116/24 brd 192.168.30.255 scope global eth0
inet 192.168.30.230/32 scope global eth0
inet6 fe80::20c:29ff:fef3:fcba/64 scope link
valid_lft forever preferred_lft forever
发现刚才定义的virtual ipaddress在master服务器上，因为优先级较高
停止master服务器的keepalived服务器，看IP会不会转移到backup
[root@master ~]# service keepalived stop
Stopping keepalived: [ OK ]
[root@backup ~]# tail -f /var/log/messages
Jan 10 12:12:46 localhost Keepalived_vrrp[18581]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 10 12:12:46 localhost Keepalived_vrrp[18581]: Configuration is using : 63017 Bytes
Jan 10 12:12:46 localhost Keepalived_vrrp[18581]: Using LinkWatch kernel netlink reflector...
Jan 10 12:12:46 localhost Keepalived_healthcheckers[18580]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 10 12:12:46 localhost Keepalived_healthcheckers[18580]: Configuration is using : 7324 Bytes
Jan 10 12:12:46 localhost Keepalived_healthcheckers[18580]: Using LinkWatch kernel netlink reflector...
Jan 10 12:12:46 localhost Keepalived_vrrp[18581]: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)]
Jan 10 12:12:47 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 10 12:12:47 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Received higher prio advert
Jan 10 12:12:47 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 10 12:16:27 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 10 12:16:28 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 10 12:16:28 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 10 12:16:28 localhost Keepalived_healthcheckers[18580]: Netlink reflector reports IP 192.168.30.230 added
Jan 10 12:16:28 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
Jan 10 12:16:33 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
[root@backup ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:5b:50:f9 brd ff:ff:ff:ff:ff:ff
inet 192.168.30.117/24 brd 192.168.30.255 scope global eth0
inet 192.168.30.230/32 scope global eth0
inet6 fe80::20c:29ff:fe5b:50f9/64 scope link
valid_lft forever preferred_lft forever
发现IP已经转移到backup服务器
下面重新启动master的keepalived
[root@master ~]# service keepalived start
Starting keepalived: [ OK ]
[root@backup ~]# tail -f /var/log/messages
Jan 10 12:12:46 localhost Keepalived_vrrp[18581]: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)]
Jan 10 12:12:47 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 10 12:12:47 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Received higher prio advert
Jan 10 12:12:47 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 10 12:16:27 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 10 12:16:28 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 10 12:16:28 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 10 12:16:28 localhost Keepalived_healthcheckers[18580]: Netlink reflector reports IP 192.168.30.230 added
Jan 10 12:16:28 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
Jan 10 12:16:33 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.30.230
Jan 10 12:18:20 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Received higher prio advert
Jan 10 12:18:20 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 10 12:18:20 localhost Keepalived_vrrp[18581]: VRRP_Instance(VI_1) removing protocol VIPs.
Jan 10 12:18:20 localhost Keepalived_healthcheckers[18580]: Netlink reflector reports IP 192.168.30.230 removed
[root@master ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:f3:fc:ba brd ff:ff:ff:ff:ff:ff
inet 192.168.30.116/24 brd 192.168.30.255 scope global eth0
inet 192.168.30.230/32 scope global eth0
inet6 fe80::20c:29ff:fef3:fcba/64 scope link
valid_lft forever preferred_lft forever
发现IP已经重新转移到master服务器
现在编写haproxy状态检测脚本，来实现haproxy的健康检测：
[root@master ~]# cat haproxy_pid.sh
#!/bin/bash
while :
do
haproxypid=`ps -C haproxy --no-header | wc -l`
if [ $haproxypid -eq 0 ];then
service haproxy start
sleep 5
haproxypid=`ps -C haproxy --no-header | wc -l`
echo $haproxypid
if [ $haproxypid -eq 0 ];then
/etc/init.d/keepalived stop
fi
fi
sleep 5
done
# 启动backup的haproxy
[root@backup ~]# service haproxy start
Starting haproxy: [ OK ]
模拟故障，先让httpd进程开启，修改haproxy监听端口为80，使得haproxy进程无法启动，看资源会不会转移到backup服务器
[root@master ~]# vi /etc/haproxy/haproxy.cfg
frontend main *:5000 改为frontend main *:80
# 启动httpd进程
[root@master ~]# scp -pr /etc/haproxy/haproxy.cfg root@192.168.30.117:/etc/haproxy/
[root@master ~]# service httpd start
Starting httpd: httpd: apr_sockaddr_info_get() failed for master.luojianlong.com
httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
[root@master ~]# netstat -antpl | grep :80