MHA之虛擬IP

在MySQL高可用之MHA部署這篇博文中，已經將MHA的基礎架構部署完成，但是并沒有解決一個虛擬IP的問題，因為當master宕機后，新的master頂上來，這時前端APP要連接的數據庫IP已經發生了變化，為了解決這個問題，必然要引入虛擬IP，談起虛擬IP，首先想到的應該是keepalived這個工具，但這個工具有個弊端，就是有一個腦裂的問題，所以更建議在生產中使用腳本的方式來控制這個VIP。

1、在manager節點寫入此腳本

[root@manager scripts]# cat /scripts/master_ip_failover 
#!/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 = '192.168.20.100';         #這里指定VIP地址
my $key = '0';
my $ssh_start_vip = "/sbin/ifconfig ens33:$key $vip";         #這條指令是啟動VIP
my $ssh_stop_vip = "/sbin/ifconfig ens33:$key down";       #這條指令是停止VIP
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" ) {
 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" ) {
 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 \" $ssh_start_vip \"`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {
 return 0 unless ($ssh_user);
 `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=port\n";
}

[root@manager ~]# ll /scripts/master_ip_failover             #需要保證腳本有可執行權限
-rwxr-xr-x 1 root root 2006 2月  24 16:32 /scripts/master_ip_failover

2、修改manager配置文件

[root@manager ~]# cat /etc/masterha/app1.cnf           #配置文件指定腳本的位置
[server default]
manager_workdir=/var/log/masterha/app1
manager_log=/var/log/masterha/app1/manager.log
user=manager
password=123.com
ssh_user=root
repl_user=mharep
repl_password=123.com
ping_interval=1
master_ip_failover_script=/scripts/master_ip_failover     #增加改行，指定腳本的位置即可。

[server1]
hostname=192.168.20.2
port=3306
master_binlog_dir=/usr/local/mysql/data
candidate_master=1

[server2]
hostname=192.168.20.3
port=3306
master_binlog_dir=/usr/local/mysql/data
candidate_master=1

[server3]
hostname=192.168.20.4
port=3306
master_binlog_dir=/usr/local/mysql/data
no_master=1

做到這里，就可以保證在切換master時，VIP地址也會隨之切換到新的master主機上。