MHA之虚拟IP

Posted 2020-11-25

在MySQL高可用之MHA部署这篇博文中，已经将MHA的基础架构部署完成，但是并没有解决一个虚拟IP的问题，因为当master宕机后，新的master顶上来，这时前端APP要连接的数据库IP已经发生了变化，为了解决这个问题，必然要引入虚拟IP，谈起虚拟IP，首先想到的应该是keepalived这个工具，但这个工具有个弊端，就是有一个脑裂的问题，所以更建议在生产中使用脚本的方式来控制这个VIP。

1、在manager节点写入此脚本

[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‘;         #这里指定VIP地址
my $key = ‘0‘;
my $ssh_start_vip = "/sbin/ifconfig ens33:$key $vip";         #这条指令是启动VIP
my $ssh_stop_vip = "/sbin/ifconfig ens33:$key down";       #这条指令是停止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 "

IN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip===

";
 if ( $command eq "stop" || $command eq "stopssh" ) {
 my $exit_code = 1;
 eval {
 print "Disabling the VIP on old master: $orig_master_host 
";
 &stop_vip();
 $exit_code = 0;
 };
 if ($@) {
 warn "Got Error: $@
";
 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

";
 &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 
";
 #`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
";
}

[root@manager ~]# ll /scripts/master_ip_failover             #需要保证脚本有可执行权限
-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           #配置文件指定脚本的位置
[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，指定脚本的位置即可。

[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

做到这里，就可以保证在切换master时，VIP地址也会随之切换到新的master主机上。