MHA之虚拟IP

青旅半醒 2023-07-08 08:00 1阅读 0赞

在[MySQL高可用之MHA部署][MySQL_MHA]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 "\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。

[MySQL_MHA]: https://blog.51cto.com/14154700/2472806