配置Keepalived实现mysql双主高可用

Posted 2020-08-11

本文为南非蚂蚁的书籍《循序渐进linux-第二版》-8.3.6的读笔记

在DB1和DB2上安装Keepalived软件

先安装编译工具

# yum install gcc* gcc-c++ autoconf automake

上传keepalived-1.2.19.tar.gz至/server/tools目录下

# cd /server/tools

# tar zxvf keepalived-1.2.19.tar.gz

# cd keepalived-1.2.19

# ./configure --sysconf=/etc --with-kernel-dir=/usr/src/kernels/2.6.32-504.el6.x86_64/

# make

# make install

# ln -s /usr/local/sbin/keepalived /sbin/

# chkconfig --add keepalived

# chkconfig --level 35 keepalived on

# cd ../

安装完成后，进入DB1的配置过程

DB1服务器上/etc/keepalived/keepalived.conf的配置内容，其中绿色字体为新增部分

! Configuration File for keepalived

global_defs {

   notification_email {

     [email protected]

     [email protected]

     [email protected]

   }

   notification_email_from [email protected]

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_scripts check_mysqld {

   scripts "/etc/keepalived/mysqlcheck/check_slave.pl 127.0.0.1"     #检测mysql复制状态的脚本

interval 2

weight 21

   }

vrrp_instance HA_1 {

   state BACKUP       #在DB1和DB2上均配置为BACKUP

interface eth0

   virtual_router_id 80

priority 90

   advert_int 2

   nopereempt         #不抢占模式，只在优先级高的机器上设置即可，优先级低的机器上不设置

authentication {

auth_type PASS

auth_pass qweasdzxc

   }

   

   track_script {

   check_mysqld

   } 

   

   virtual_ipaddress {

     10.24.24.110/24 dev eth0        #mysql的对外服务IP，即VIP

   }

}

vrrp_instance VI_1 {

    state MASTER

    interface eth0

    virtual_router_id 51

    priority 100

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.200.16

        192.168.200.17

        192.168.200.18

    }

}

-----------------------------------------

# mkdir /etc/keepalived/mysqlcheck/

其中，/etc/keepalived/mysqlcheck/check_slave.pl文件的内容如下：

# vim /etc/keepalived/mysqlcheck/check_slave.pl

#!/usr/bin/perl -w

use DBI;

use DBD::mysql;

# CONFIG VARIABLES

$SBM = 120;

$db = "ywadmin";

$host = $ARGV[0];

$port = 3306;

$user = "root";

$pw = "jzh0024";

# SQL query

$query = "show slave status";

$dbh = DBI->connect("DBI:mysql:$db:$host:$port", $user, $pw, { RaiseError => 0,PrintError => 0 });

if (!defined($dbh)) {

    exit 1;

}

$sqlQuery = $dbh->prepare($query);

$sqlQuery->execute;

$Slave_IO_Running =  "";

$Slave_SQL_Running = "";

$Seconds_Behind_Master = "";

while (my $ref = $sqlQuery->fetchrow_hashref()) {

    $Slave_IO_Running = $ref->{‘Slave_IO_Running‘};

    $Slave_SQL_Running = $ref->{‘Slave_SQL_Running‘};

    $Seconds_Behind_Master = $ref->{‘Seconds_Behind_Master‘};

}

$sqlQuery->finish;

$dbh->disconnect();

if ( $Slave_IO_Running eq "No" || $Slave_SQL_Running eq "No" ) {

    exit 1;

} else {

    if ( $Seconds_Behind_Master > $SBM ) {

        exit 1;

    } else {

        exit 0;

    }

}

只需要修改红色的数据库名\数据库端口\用户名和密码即可

添加可执行权限

# chmod +x /etc/keepalived/mysqlcheck/check_slave.pl

将keepalived.conf和check_slave.pl文件复制到DB2服务器对应的位置，将DB2上的keepalived.conf中的priority值修改为90，同时去掉nopreempt选项

DB2上

[[email protected] keepalived]# mkdir /etc/keepalived/mysqlcheck/

[[email protected] keepalived]# cd /etc/keepalived/mysqlcheck/

上传check_slave.pl脚本

[[email protected] mysqlcheck]# rz

[[email protected] mysqlcheck]# ll

total 4

-rw-r--r-- 1 root root 919 Sep 12 14:57 check_slave.pl

[[email protected] mysqlcheck]# chmod +x check_slave.pl 

完成所有配置后，分别启动DB1和DB2上启动keepalived服务，正常情况下VIP地址应该运行在DB1服务器上

[[email protected] tools]# /etc/init.d/keepalived start

Starting keepalived:                                       [  OK  ]

[[email protected] keepalived]# /etc/init.d/keepalived start

Starting keepalived:                                       [  OK  ]

======================================================

8.3.7 测试mysql主从同步功能

首先在DB1,DB2上添加远程访问授权;

DB1上授权

mysql> grant all on *.* to ‘root‘@‘10.24.24.%‘ identified by ‘jzh0024‘;

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from mysql.user;

DB2上授权

mysql> grant all on *.* to ‘root‘@‘10.24.24.%‘ identified by ‘jzh0024‘;

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> select user,host from mysql.user;

1.在远程客户端通过VIP登录测试

[[email protected] ~]# mysql -uroot -p -h 10.24.24.110

Enter password: 

mysql> show variables like "%hostname%";

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| hostname      | DB1   |

+---------------+-------+

1 row in set (0.00 sec)

mysql> show variables like "%server_id%";

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| server_id     | 1     |

+---------------+-------+

1 row in set (0.00 sec)

从SQL输出结果看,可以通过VIP登录,并且登录到了DB1服务器

2.数据复制功能测试

[[email protected] ~]# mysql -uroot -p -h 10.24.24.110

Enter password: 

mysql> create database repldb;

Query OK, 1 row affected (0.00 sec)

mysql> use repldb;

Database changed

mysql> create table repl_table(id int,email varchar(86),password varchar(40) not null);

Query OK, 0 rows affected (0.00 sec)

mysql> show tables;

+------------------+

| Tables_in_repldb |

+------------------+

| repl_table       |

+------------------+

1 row in set (0.00 sec)

mysql> insert into repl_table (id,email,password) values(1,"[email protected]","qwessd");

Query OK, 1 row affected (0.00 sec)

mysql> select * from repl_table;

+------+----------------+----------+

| id   | email          | password |

+------+----------------+----------+

|    1 | [email protected] | qwessd   |

+------+----------------+----------+

1 row in set (0.00 sec)

在DB2数据库中查询数据是否已经同步

mysql> show databases;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| db01               |

| db02               |

| mysql              |

| repldb             |

| ywadmin            |

+--------------------+

6 rows in set (0.00 sec)

mysql> use repldb;

Database changed

mysql> show tables;

+------------------+

| Tables_in_repldb |

+------------------+

| repl_table       |

+------------------+

1 row in set (0.00 sec)

mysql> select * from repl_table;

+------+----------------+----------+

| id   | email          | password |

+------+----------------+----------+

|    1 | [email protected] | qwessd   |

+------+----------------+----------+

1 row in set (0.00 sec)

证明在其他mysql客户端登录写入VIP的数据已经同步到DB2数据库中。

======================================================

8.3.8 测试keepalived实现mysql故障切换

为了测试keepalived实现的故障切换功能，需要模拟一些故障。

比如，可以断开DB1主机的网络、关闭DB1主机、关闭DB1上mysql服务等各种操作实现；

这里停止DB1服务器的网络连接，模拟DB1的mysql故障；

由于在DB1、DB2服务器上都添加了监控MYSQL运行状态的脚本 check_slave.pl，因此当关闭DB1的MYSQL日志接收功能后，keepalived会立刻检测到，接着执行切换操作

测试过程如下：

1.停止DB1服务器的网络连接

在远程mysql客户端以VIP地址登录到mysql系统中，不要退出这个连接；

中断DB1服务器的网络连接;

[[email protected] ~]# /etc/init.d/network stop

2.在mysql远程客户端测试

继续在刚才打开的远程mysql连接中执行命令

mysql> show variables like "%hostname%";

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| hostname      | DB2   |

+---------------+-------+

1 row in set (0.00 sec)

mysql> show variables like "%server_id%";

+---------------+-------+

| Variable_name | Value |

+---------------+-------+

| server_id     | 2     |

+---------------+-------+

1 row in set (0.00 sec)

接着重新开启DB1的网络连接，发现keepalived将不再执行切换操作了，因为上面将keepalived配置为抢占模式了。

此时，mysql服务将一直在DB2服务器上运行，每次切换的代价很大，因而关闭了keepalived的主动抢占模式。

本文出自 “Linux运维的自我修养” 博客，请务必保留此出处http://ywliyq.blog.51cto.com/11433965/1856964