MHA群集管理

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环境：

192.168.205.37: as MHA server
192.168.205.47: as Master server
192.168.205.57: as Slave1 server
192.168.205.67: as Slave2 server

版本：

OS: centos 7 1810 with mini install
mariadb-server 5.5.60
mha4MySQL-manager-0.56-0.el6.noarch.rpm
mha4mysql-node-0.56-0.el6.noarch.rpm

目地：

MHA使用perl脚本写的程序，当主节点down时如果从节点复制没有完成时，当他成为主节点后，它需要尝试将主节点的二进制日志复制到新的主节点，从而保证数据的完整性，所以它需要sshkey验证。我们使用一台做为管理节点，其中三个为数据库节点，一主两从，模拟主节点down机，看从是如何被提升为主节点的。

安装数据库

安装mariadb使用如下脚本：

[root@master data]#cat maridb_yum.sh 
#!/bin/bash
ID=`ip a show dev eth0 | sed -r '3!d;s@(.*inet)(.*)(/.*)@\2@' | cut -d. -f4`
rpm -q mariadb-server ||yum install -y mariadb-server
[ -d /data/mysql ] || mkdir -p /data/mysql
[ -d /data/logs ] || mkdir -p /data/logs
chown mysql:mysql /data/{mysql,logs}
sed -i 's@datadir=/var/lib/mysql@datadir=/data/mysql@' /etc/my.cnf
grep "log-bin" /etc/my.cnf || sed -i '/\[mysqld\]/a log-bin=/data/logs/bin' /etc/my.cnf
grep "innodb_file_per_table" /etc/my.cnf || sed -i '/\[mysqld\]/a innodb_file_per_table = on' /etc/my.cnf
grep "skip_name_resolve" /etc/my.cnf || sed -i '/\[mysqld\]/a skip_name_resolve = on' /etc/my.cnf
grep "server-id" /etc/my.cnf || sed -i "/\[mysqld\]/a server-id=$ID" /etc/my.cnf
service mariadb restart

修改两个从节点的配置文件

[root@slave1 data]#vi /etc/my.cnf
[mysqld]
read_only   
relay_log_purge=0     #不删除中继日志

建立主节点的复制位置和帐号

MariaDB [(none)]> show master logs;
+------------+-----------+
| Log_name   | File_size |
+------------+-----------+
| bin.000001 |     30373 |
| bin.000002 |   1038814 |
| bin.000003 |       245 |
+------------+-----------+
3 rows in set (0.00 sec)

MariaDB [(none)]> grant replication slave on *.* to repluser@'192.168.205.%' identified by 'centos';
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> grant all on *.* to mhauser@'192.168.205.%' identified by 'centos'; 
Query OK, 0 rows affected (0.00 sec)

配置从节点的change master to并启动线程

MariaDB [(none)]> CHANGE MASTER TO
    ->   MASTER_HOST='192.168.205.47',
    ->   MASTER_USER='repluser',
    ->   MASTER_PASSWORD='centos',
    ->   MASTER_PORT=3306,
    ->   MASTER_LOG_FILE='bin.000003',
    ->   MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.205.47
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: bin.000003
          Read_Master_Log_Pos: 401
               Relay_Log_File: mariadb-relay-bin.000002
                Relay_Log_Pos: 679
        Relay_Master_Log_File: bin.000003
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

MHA实现

安装包，mha依赖epel源，我们要把epel起用

[root@MHA ~]#yum install mha4mysql-manager-0.56-0.el6.noarch.rpm mha4mysql-node-0.56-0.el6.noarch.rpm

在所有的sql节点上安装node包

[root@master ~]#yum install mha4mysql-node-0.56-0.el6.noarch.rpm 
[root@slave1 data]#yum install mha4mysql-node-0.56-0.el6.noarch.rpm 
[root@slave2 data]#yum install mha4mysql-node-0.56-0.el6.noarch.rpm

配置ssh key 验证

[root@MHA ~]#ssh-keygen 
[root@MHA ~]#ssh-copy-id 192.168.205.37
[root@MHA ~]#cat .ssh/authorized_keys 
[root@MHA ~]#scp -r .ssh 192.168.205.47:/root/
[root@MHA ~]#scp -r .ssh 192.168.205.57:/root/
[root@MHA ~]#scp -r .ssh 192.168.205.67:/root/

生成配置MHA文件

[root@MHA ~]#mkdir /etc/mha
[root@MHA ~]#vim /etc/mha/app1.cnf
[server default]
master_binlog_dir=/data/logs/ 
user=mhauser
password=centos
manager_workdir=/data/mastermha/app1/
manager_log=/data/mastermha/app1/manager.log
remote_workdir=/data/mastermha/app1/
ssh_user=root
repl_user=repluser
repl_password=centos
ping_interval=1
[server1]
hostname=192.168.205.47
candidate_master=1
[server2]                                                                                                                          
hostname=192.168.205.57
[server3]
hostname=192.168.205.67
candidate_master=1

启动之前进行检查ssh，repl复制是否准备好

[root@MHA ~]#masterha_check_ssh --conf=/etc/mha/app1.cnf
[root@MHA ~]#masterha_check_repl --conf=/etc/mha/app1.cnf

起动进程，此进程前台运行，当主节点失败时切换完成后它会终止，所以要想持续要重启进程

[root@MHA ~]#masterha_manager --conf=/etc/mha/app1.cnf
Mon Aug 12 23:33:22 2019 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Mon Aug 12 23:33:22 2019 - [info] Reading application default configuration from /etc/mha/app1.cnf..
Mon Aug 12 23:33:22 2019 - [info] Reading server configuration from /etc/mha/app1.cnf..

测试

我们模拟一个正在写入操作时，主节点down, 看服务器能不能正常切换并不能复制丢失的数据

MariaDB [(none)]> use test;
Database changed
MariaDB [test]> create table testlog (id int auto_increment primary key,name char(10),age int default 20);

Query OK, 0 rows affected (0.01 sec)

MariaDB [test]> 
MariaDB [test]> delimiter $$
MariaDB [test]> 
MariaDB [test]> create procedure  sp_testlog() 
    -> begin  
    -> declare i int;
    -> set i = 1; 
    -> while i <= 100000 
    -> do  insert into testlog(name,age) values (concat('wang',i),i); 
    -> set i = i +1; 
    -> end while; 
    -> end$$
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> 
MariaDB [test]> delimiter ;
MariaDB [test]> call sp_testlog;

正在写入数据时我们及时关闭47服务器，MHA检测到节点，并响应，成功提升其它的为主后退出程序。

[root@MHA ~]#masterha_manager --conf=/etc/mha/app1.cnf
Mon Aug 12 23:33:22 2019 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Mon Aug 12 23:33:22 2019 - [info] Reading application default configuration from /etc/mha/app1.cnf..
Mon Aug 12 23:33:22 2019 - [info] Reading server configuration from /etc/mha/app1.cnf..
Mon Aug 12 23:45:16 2019 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping.
Mon Aug 12 23:45:16 2019 - [info] Reading application default configuration from /etc/mha/app1.cnf..
Mon Aug 12 23:45:16 2019 - [info] Reading server configuration from /etc/mha/app1.cnf..
[root@MHA ~]#

我们可以查看日志看一下发生的情况，slave2提升为主

[root@MHA data]#cat mastermha/app1/manager.log 
----- Failover Report -----

app1: MySQL Master failover 192.168.205.47(192.168.205.47:3306) to 192.168.205.67(192.168.205.67:3306) succeeded

Master 192.168.205.47(192.168.205.47:3306) is down!

Check MHA Manager logs at MHA:/data/mastermha/app1/manager.log for details.

Started automated(non-interactive) failover.
The latest slave 192.168.205.57(192.168.205.57:3306) has all relay logs for recovery.
Selected 192.168.205.67(192.168.205.67:3306) as a new master.
192.168.205.67(192.168.205.67:3306): OK: Applying all logs succeeded.
192.168.205.57(192.168.205.57:3306): This host has the latest relay log events.
Generating relay diff files from the latest slave succeeded.
192.168.205.57(192.168.205.57:3306): OK: Applying all logs succeeded. Slave started, replicating from 192.168.205.67(192.168.205.67:3306)
192.168.205.67(192.168.205.67:3306): Resetting slave info succeeded.
Master failover to 192.168.205.67(192.168.205.67:3306) completed successfully.

我们来核实一下，在slave2上看一下slave的状态，发现已经没了，因为它是主
```
MariaDB [(none)]> show slave status\G
Empty set (0.00 sec)
```

检查一下slave1，发现主节点指向了slave2

MariaDB [test]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.205.67
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: bin.000005
          Read_Master_Log_Pos: 245
               Relay_Log_File: mariadb-relay-bin.000002
                Relay_Log_Pos: 523
        Relay_Master_Log_File: bin.000005
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

在新主节点上看一下是否将read_only off掉，发现是，但不要忘记改回配置文件，如果重启的话又会变成read_only

MariaDB [(none)]> show variables like 'read_only';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | OFF   |
+---------------+-------+
1 row in set (0.00 sec)

本文题目：MHA群集管理
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MHA群集管理

环境：

版本：

目地：

安装数据库

MHA实现

测试

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