虚拟ip飘逸说到Failover，通常有两种方式：一种是虚拟IP地址，一种是全局配置文件。
MHA并没有限定使用哪一种方式，而是让用户自己选择，虚拟IP地址的方式会牵扯到其它的软件，这里就不赘述了上篇文章搭建mha+keepalive就是通过keepalive来控制虚拟ip，本片文章在介绍一种虚拟ip的方式

配置虚拟ip采用ifconfig的方式/sbin/ifconfig eth0:1 192.168.6.66/24
删除VIP:
/sbin/ifconfig eth0:1 down网上找了一个master_ip_failover脚本就是用此方法更改VIP:
[root@localhost app1]# more /usr/local/bin/master_ip_online_change_script
#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';

use Getopt::Long;

my (
$command, $ssh_user, $orig_master_host, $orig_master_ip,
$orig_master_port, $new_master_host, $new_master_ip, $new_master_port
);

my $vip = '192.168.6.66/24'; # Virtual IP
my $key = "1";
my $ssh_start_vip = "/sbin/ifconfig eth0:$key $vip";
my $ssh_stop_vip = "/sbin/ifconfig eth0:$key down";

GetOptions(
'command=s' => \$command,
'ssh_user=s' => \$ssh_user,
'orig_master_host=s' => \$orig_master_host,
'orig_master_ip=s' => \$orig_master_ip,
'orig_master_port=i' => \$orig_master_port,
'new_master_host=s' => \$new_master_host,
'new_master_ip=s' => \$new_master_ip,
'new_master_port=i' => \$new_master_port,
);

exit &main();

sub main {

print "\n\nIN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===\n\n";

if ( $command eq "stop" || $command eq "stopssh" ) {

# $orig_master_host, $orig_master_ip, $orig_master_port are passed.
# If you manage master ip address at global catalog database,
# invalidate orig_master_ip here.
my $exit_code = 1;
eval {
print "Disabling the VIP on old master: $orig_master_host \n";
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@\n";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {

# all arguments are passed.
# If you manage master ip address at global catalog database,
# activate new_master_ip here.
# You can also grant write access (create user, set read_only=0, etc) here.
my $exit_code = 10;
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host \n";
&start_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Checking the Status of the script.. OK \n";
`ssh $ssh_user\@cluster1 \" $ssh_start_vip \"`;
exit 0;
}
else {
&usage();
exit 1;
}
}

# A simple system call that enable the VIP on the new master
sub start_vip() {
`ssh $ssh_user\@$new_master_host \" $ssh_start_vip \"`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {
`ssh $ssh_user\@$orig_master_host \" $ssh_stop_vip \"`;
}

sub usage {
print
"Usage: master_ip_failover --command=start|stop|stopssh|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --new_master_host=host --new_master_ip=ip --new_master_port=po
rt\n";
}

将此脚本复制两次到/usr/local/bin, 分别命名为master_ip_failover 和master_ip_online_change_script

然后将/etc/app1.cnf 中下面两行注释去掉：

master_ip_failover_script=/usr/local/bin/master_ip_failovermaster_ip_online_change_script=/usr/local/bin/master_ip_online_change_script

实验
1.主库（115）添加一个vip[root@node2 .ssh]# /sbin/ifconfig eth0:1 192.168.6.66/24
[root@node2 .ssh]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
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 qlen 1000
link/ether 08:00:27:03:1b:a1 brd ff:ff:ff:ff:ff:ff
inet 192.168.6.115/24 brd 192.168.6.255 scope global eth0
inet 192.168.6.66/24 brd 192.168.6.255 scope global secondary eth0:1
inet6 fe80::a00:27ff:fe03:1ba1/64 scope link
valid_lft forever preferred_lft forever
2.关闭主库mysql[root@node2 .ssh]# /etc/init.d/mysqld stop
Stopping mysqld: [ OK ]
[root@node2 .ssh]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
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 qlen 1000
link/ether 08:00:27:03:1b:a1 brd ff:ff:ff:ff:ff:ff
inet 192.168.6.115/24 brd 192.168.6.255 scope global eth0 ---vip飘走了
inet6 fe80::a00:27ff:fe03:1ba1/64 scope link
valid_lft forever preferred_lft forever

3 查看newmaster（114）的ip ----vip已飘到new master上了[root@node1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue
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 qlen 1000
link/ether 08:00:27:7a:c6:9c brd ff:ff:ff:ff:ff:ff
inet 192.168.6.114/24 brd 192.168.6.255 scope global eth0
inet 192.168.6.66/24 brd 192.168.6.255 scope global secondary eth0:1
inet6 fe80::a00:27ff:fe7a:c69c/64 scope link
valid_lft forever preferred_lft forever

4 重构mysql.重启mha监控5 关闭114mysql，vip飘回115上去了