Linux实战之MySQL数据库——keepalived实现Mysql双主高可用
Mysql双主高可用介绍
架构介绍
Mysql的双主高可用架构，主要设计思想是两台Mysql服务器通过Mysql复制技术互相将对方作为自己的主服务器，自己又同时作为对方的从服务器来进行复制，实现高可用架构中的数据同步功能，同时采用keepalived来实现mysql的自动故障切换
在这个架构中，两台Mysq|服务器互为主从，同一时刻只有一个Mysql服务器可读写，另一个Mysql服务器只能进行读操作，保证数据的一致性
Keepalived的作用
（1）Keepalived维护一个VIP，此IP用来对外部提供链接服务
（2）keepalived负责监控DB1和DB2上Mysql数据库的运行状态，DB1故障时自动将VIP地址和Mysql服务切换到DB2上
总结： 通过Keepalived保持数据库服务的连续性，整个切换过程非常快，并且对前端Web服务器主机透明
主主互备模式不足
- 从库可能会一直处于空闲状态 可以用它当从库，负责部分查询
- 从库要先与主库同步数据才能提供服务，造成一定程度的同步延时
Mysql双主高可用实现
建议采用高可用策略的时候，masterA或masterB均不因宕机恢复后而抢占VIP（非抢占模式），尽可能减少主库宕机对业务造成的影响，减少主从同步给线上主库带来的压力
主主互备模式配置
初始化环境
同步时间
关闭防火墙
环境规划
| 主机 | IP | Server_ID |
|---|---|---|
| server1：mysql | 192.168.213.124 | 1 |
| server2：mysql-1 | 192.168.213.127 | 2 |
配置server2
[root@mysql-1 ~]# vim /etc/my.cnf
[mysqld]
server_id=2
#master必备
log-bin=mysql-bin
log-bin-index=master-bin.index
#slave必备
relay-log=relay-log
relay-log-index=relay-log.index
重启服务
[root@localhost ~]# systemctl restart mysqld
在server1和server2上分别创建一个用于让从数据库连接的用户
mysql> create user 'copy'@'%' identified with mysql_native_password by 'Cloudbu@123';
mysql> grant replication slave on *.* to 'copy'@'%';
mysql> flush privileges; 刷新授权表信息
在server1上获取当前主节点当前binary log文件名和位置
[root@mysql ~]# mysql -uroot -pZhao123@com
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000002 | 155 | | | |
+------------------+----------+--------------+------------------+-------------------+
设置主节点参数
[root@mysql-1 ~]# mysql -uroot -pZhao123@com
mysql> CHANGE MASTER TO
MASTER_HOST='192.168.213.124',
MASTER_USER='copy',
MASTER_PASSWORD='Cloudbu@123',
MASTER_LOG_FILE='mysql-bin.000002',
MASTER_LOG_POS=155;
查看主从同步状态
mysql> show slave status\G
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
#其中的IO线程和SQL线程均为YES，则配置成功
配置server1
修改配置文件，必须指定中继日志的名称
[root@mysql ~]# vim /etc/my.cnf
[mysqld]
server_id=1
#master必备
log-bin=mysql-bin
log-bin-index=master-bin.index
#slave必备
relay-log=relay-log
relay-log-index=relay-log.index
重启服务
[root@localhost ~]# systemctl stop mysqld
[root@localhost ~]# systemctl start mysqld
在server1上获取当前主节点当前binary log文件名和位置
[root@mysql-1 ~]# mysql -uroot -pZhao123@com
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 825 | | | |
+------------------+----------+--------------+------------------+-------------------+
设置主节点参数
[root@mysql-1 ~]# mysql -uroot -pZhao123@com
mysql> CHANGE MASTER TO
MASTER_HOST='192.168.213.127',
MASTER_USER='copy',
MASTER_PASSWORD='Cloudbu@123',
MASTER_LOG_FILE='mysql-bin.000002',
MASTER_LOG_POS=825;
查看主从同步状态
mysql> show slave status\G
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
#其中的IO线程和SQL线程均为YES，则配置成功
keepalived配置
安装keepalived
两台服务器上都需要安装
（1）安装软件
[root@mysql ~]# wget https://www.keepalived.org/software/keepalived-2.0.1.tar.gz
[root@mysql ~]# mkdir -p /data/keepalived
[root@mysql ~]# tar -xf keepalived-2.0.1.tar.gz -C /usr/local/src
[root@mysql ~]# yum install openssl-devel gcc gcc-c++ make -y
[root@mysql ~]# cd /usr/local/src/keepalived-2.0.1
[root@mysql keepalived-2.0.1]# ./configure --prefix=/data/keepalived/
[root@mysql keepalived-2.0.1]# echo $?
0
[root@mysql keepalived-2.0.1]# make
[root@mysql keepalived-2.0.1]# echo $?
0
[root@mysql keepalived-2.0.1]# make install
[root@mysql keepalived-2.0.1]# echo $?
0
（2）配置规范启动
[root@bogon etc]# pwd
/usr/local/src/keepalived-2.0.1/keepalived/etc
[root@mysql etc]# pwd
/usr/local/src/keepalived-2.0.1/keepalived/etc
[root@mysql etc]# cp -R init /data/keepalived/
[root@mysql etc]# cp -R init /data/keepalived/etc/
[root@mysql etc]# cp -R init.d /data/keepalived/etc/
[root@mysql etc]# ll /data/keepalived/etc/
total 0
drwxr-xr-x 2 root root 86 Mar 3 20:25 init
drwxr-xr-x 2 root root 135 Mar 3 20:25 init.d
drwxr-xr-x 3 root root 44 Mar 3 20:23 keepalived
drwxr-xr-x 2 root root 24 Mar 3 20:23 sysconfig
[root@mysql etc]# cp /data/keepalived/etc/init.d/keepalived /etc/init.d/
[root@mysql etc]# cp /data/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@mysql etc]# mkdir /etc/keepalived
[root@mysql etc]# cp /data/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@mysql etc]# cp /data/keepalived/sbin/keepalived /usr/sbin/
（3）启动
[root@mysql ~]# /etc/init.d/keepalived start
Starting keepalived (via systemctl): [ OK ]
[root@mysql ~]# ps -ef |grep keepalived
root 7935 1 9 20:28 ? 00:00:01 /data/keepalived/sbin/keepalived -D
root 7936 7935 0 20:28 ? 00:00:00 /data/keepalived/sbin/keepalived -D
root 20466 3788 0 20:28 pts/1 00:00:00 grep --color=auto keepalived
root 20490 7935 0 20:28 ? 00:00:00 [keepalived] <defunct>
keepalived配置
keepalived中的两种模式
（1）master->backup模式
一旦主库宕机，虚拟ip会自动漂移到从库，当主库修复后，keepalived启动后，还会把虚拟ip抢占过来，即使设置了非抢占模式（nopreempt）抢占ip的动作也会发生。
（2）backup->backup模式
当主库宕机后虚拟ip会自动漂移到从库上，当原主库恢复和keepalived服务启动后，并不会抢占新主的虚拟ip，即使是优先级高于从库的优先级别，也不会发生抢占。为了减少ip漂移次数，通常是把修复好的主库当做新的备库。
在数据库的应用场景中，不建议数据库的频繁切换，因此，将其配置为keepalived的VIP不抢占模式，具体配置如下：
在mysql上
[root@mysql ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id HA_MYSQL01
}
vrrp_script check_mysqld {
script "/etc/keepalived/check_mysqld.sh"
interval 2
}
vrrp_instance HA_1 {
state BACKUP
interface ens33
virtual_router_id 51
priority 150
advert_int 1
nopreempt
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.213.233
}
track_script {
check_mysqld
}
}
state BACKUP #在ser01和ser02上均配置为backup
nopreempt #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
在mysql-1上
[root@mysql-1 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id HA_MYSQL01
}
vrrp_script check_mysqld {
script "/etc/keepalived/check_mysqld.sh"
interval 2
}
vrrp_instance HA_1 {
state BACKUP
interface ens33
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.213.233
}
track_script {
check_mysqld
}
}
监控脚本
[root@mysql ~]# cat /etc/keepalived/check_mysqld.sh
#!/bin/bash
user=root
pass=Zhao123@com
/usr/bin/mysql -u$user -p$pass -e "show status;" > /dev/null 2>&1
if [ $? -eq 0 ];
then
MYSQL_STATUS=0
else
MYSQL_STATUS=1
fi
exit $MYSQL_STATUS
[root@mysql ~]# chmod +x /etc/keepalived/check_mysqld.sh
Mysql配置账号测试
（1）授权账号
mysql> create user 'keepalived'@'%' identified by 'Cloudbu@123';
mysql> ALTER USER 'keepalived'@'%' IDENTIFIED WITH mysql_native_password BY
'Cloudbu@123';
mysql> flush privileges;
（2）结果测试
在测试节点上用192.168.213.233，即浮动ip测试
[root@configure ~]# mysql -h192.168.213.233 -ukeepalived -pCloudbu@123
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
+--------------------+
1 row in set (0.00 sec)
关闭优先级别较高的mysql，VIP会漂移到mysql-1上，客户端连接会显示如下信息，但可重新登录上
[root@configure ~]# mysql -h192.168.213.233 -ukeepalived -pCloudbu@123
mysql> show databases;
ERROR 2013 (HY000): Lost connection to MySQL server during query
[root@configure ~]# mysql -h192.168.213.233 -ukeepalived -pCloudbu@123
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
+--------------------+
当mysql恢复后，能够实现数据同步，vip并没有漂移回mysql上，而是保持在mysql-1上；当mysql-1故障后，VIP自然漂移到了mysql上