keepalived+MySQL双主实现高可用性

使用MySQL主主复制技术+Keepalived是一种简单、便捷的解决方案，在高可用集群环境中，keepalived使用虚拟VIP，使用Keepalived自带的服务监控功能和自定义脚本来实现MySQL故障时自动切换，非常灵活。如果有一台MySQL服务器死机，或工作出现故障，keepalived将检测到，并将有故障的MySQL服务器从系统中去除。当MySQL服务器工作正常时，则自动将MySQL服务器加入到服务器集群中，无需人工干预。下面环境为debugo01、debugo02两个节点，使用CentOS 6.6系统。MySQL server的版本是Percona Server 5.6.21，已经配置好了两边的MySQL实例。

1. 配置MySQL Multi-Master Replication

编辑my.cnf文件，添加相关复制选项。

vim /etc/my.cnf
server-id=1002
log-bin=mysql-bin
relay-log=mysqld-relay-bin
binlog_format=mixed
replicate_ignore_db=information_schema
auto-increment-increment=2
auto-increment-offset=1

#debugo01
mysql> show master status \G
*************************** 1. row ***************************
             File: mysql-bin.000001
         Position: 648
     Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: 
1 row in set (0.01 sec)
mysql> grant replication slave,replication client on *.* to rep@'%' identified by 'debugo';
mysql> flush privileges;
#debugo02
mysql> grant replication slave,replication client on *.* to rep@'%' identified by 'debugo';
mysql> flush privileges;
mysql> CHANGE MASTER TO MASTER_HOST='debugo01', MASTER_USER='rep', MASTER_PASSWORD='debugo', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=648;
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

#debugo01
mysql> CHANGE MASTER TO MASTER_HOST='debugo02', MASTER_USER='rep', MASTER_PASSWORD='debugo', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=426;
mysql> start slave;

vim /etc/my.cnf

server-id=1002

log-bin=mysql-bin

relay-log=mysqld-relay-bin

binlog_format=mixed

replicate_ignore_db=information_schema

auto-increment-increment=2

auto-increment-offset=1

#debugo01

mysql> show master status \G

*************************** 1. row ***************************

File: mysql-bin.000001

Position: 648

Binlog_Do_DB:

Binlog_Ignore_DB:

Executed_Gtid_Set:

1 row in set (0.01 sec)

mysql> grant replication slave,replication client on *.* to rep@'%' identified by 'debugo';

mysql> flush privileges;

#debugo02

mysql> grant replication slave,replication client on *.* to rep@'%' identified by 'debugo';

mysql> flush privileges;

mysql> CHANGE MASTER TO MASTER_HOST='debugo01', MASTER_USER='rep', MASTER_PASSWORD='debugo', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=648;

mysql> start slave;

Query OK, 0 rows affected (0.01 sec)

#debugo01

mysql> CHANGE MASTER TO MASTER_HOST='debugo02', MASTER_USER='rep', MASTER_PASSWORD='debugo', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=426;

mysql> start slave;

检查日志，没有错误说明配置成功。

2. 配置keepalived

CentOS 6.6的光盘中已经带了keepalived-1.2.13-4的软件包，通过yum安装即可：
yum install keepalived
完成后编辑keepalived.conf文件

vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id Keepalived_MySQL
}

vrrp_script check_run {
    script "/etc/keepalived/check_MySQL.sh"
    interval 5
}

vrrp_sync_group VG1{
    group {
        VI_1
    }
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth1
    virtual_router_id 51
    priority 100
    advert_int 1
    nopreempt
    track_script {
        check_run
    }
    authentication {
        auth_type PASS
        auth_pass debugo
    }
    virtual_ipaddress {
        10.6.2.200
    }
}

vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

router_id Keepalived_MySQL

}

vrrp_script check_run {

script "/etc/keepalived/check_MySQL.sh"

interval 5

}

vrrp_sync_group VG1{

group {

VI_1

}

vrrp_instance VI_1 {

state BACKUP

interface eth1

virtual_router_id 51

priority 100

advert_int 1

nopreempt

track_script {

check_run

}

authentication {

auth_type PASS

auth_pass debugo

}

virtual_ipaddress {

10.6.2.200

}

配置说明(参考官方文档，Keepalived+LVS 集群的部署和keepalived.conf 文件详解)
keepalived 的全局配置文件对keepalived起效的配置，而VRRPD 是keepalived 的核心，LVS配置只是需要使用keepalived来配置和管理LVS时需要使用，当然如果是只用keepalived 配置高可用集群是，LVS模块就不需要配置。配置文件都是以块的形式组织的，每个模块的配置都需要用 { } 的范围之内
在keepalived 的主配置文件中主要分为三个文本模块分别是：
全局模块（Global Configuration），VRRPD配置模块（VRRP 实例模块），LVS模块（虚拟服务模块）；
1. 全局配置（Global Configuration） 包括两个部分：即全局定义（global definition）和静态地址路由（Static ipaddress /routes）。全局定义：主要是设置Keeplived 的通知机制和标识，同时也不建议用该方法进行状态监控，进行状态监控时nagios 是不二的选择。静态地址路由：该处是配置静态地址和静态路由的，换句话说不随着Vrrp instance的开关的变化而变化，当然VIP不是static IPaddress，会随着VRRPD而添加和删除，设置静态地址和静态路由的格式如：src $SRC_IP to $DST_IP dev $SRC_DEVICE 或者src $SRC_IP to $DST_IP via $GW dev $SRC_DEVICE2. VRRPD 配置包括三个部分: 分别是VRRP脚本(VRRP scripts) . VRRP同步组（syncgriuzation group）和VRRP 实例（VRRP Instance）：
2. VRRP scripts: 脚本会安周期性执行，每秒（或者按照自己设定的时间间隔），被监控的实例会记录退出的代码，这些脚本被至少有被监控的实例的权重为o的实例才能执行，因此任意脚本可能的声明都不会被系统所记录，如果没有特殊的设置，权重等于2，就意味着那些被监控的实例的优先级会被增加2，反过来，如果失败，则那些实例的优先级会被减去2
3. syncgriuzation group: 如果不使用 VRRP Sync Groups 如果keepalived 主机有两个网段，每个网段开启一个VRRP 实例，如果对外的网段出现问题，VRRPD认为自己仍然认为健康，因此 Master和Backup 相互切换，从而导致服务不能正常使用，同时高可用集群也不能正常运行，Sync group 就是为了解决该问题
注意：
router_id : 标识当前节点.两个节点即可以相同，也可以不同。
virtual_router_id : 这个标识是同一个vrrp实例使用唯一的标识。即同一个vrrp_stance,MASTER和BACKUP的virtual_router_id是一致的，同时在整个vrrp内是唯一的。
而priority 一般MASTER可以设置大一些。
vrrp_script中，MySQL的检测脚本如下，当检测到MySQL失败后，virtual_ipaddress会飘逸到BACKUP上。

vim /etc/keepalived/check_MySQL.sh
#!/bin/bash
MYSQL=/usr/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=root
CHECK_COUNT=5

counter=1
while true
do
        mysql -h $MYSQL_HOST -u $MYSQL_USER -e "show status;"  >/dev/null 2>&1
        i=$?
        ps aux | grep mysqld | grep -v grep > /dev/null 2>&1
        j=$?
        if [ $i = 0 ] && [ $j = 0 ]
        then
                exit 0
        else
                if [ $i = 1 ] && [ $j = 0 ]
                then
                        exit 0
                else
                        if [ $counter -gt $CHECK_COUNT ]
                        then
                                break
                        fi
                let counter++
                continue
                fi
        fi
        done
/etc/init.d/keepalived stop
exit 1

vim /etc/keepalived/check_MySQL.sh

#!/bin/bash

MYSQL=/usr/bin/mysql

MYSQL_HOST=localhost

MYSQL_USER=root

CHECK_COUNT=5

counter=1

while true

mysql -h $MYSQL_HOST -u $MYSQL_USER -e "show status;" >/dev/null 2>&1

i=$?

ps aux | grep mysqld | grep -v grep > /dev/null 2>&1

j=$?

if [ $i = 0 ] && [ $j = 0 ]

then

exit 0

else

if [ $i = 1 ] && [ $j = 0 ]

then

exit 0

else

if [ $counter -gt $CHECK_COUNT ]

then

break

let counter++

continue

done

/etc/init.d/keepalived stop

exit 1

3. 测试

启动keepalived
service keepalived start
此时，在/var/log/messages中可以看到定期check_run脚本执行成功：

.....
Jan 21 19:58:35 debugo02 Keepalived_vrrp[22065]: VRRP_Script(check_run) succeeded
......

.....

Jan 21 19:58:35 debugo02 Keepalived_vrrp[22065]: VRRP_Script(check_run) succeeded

......

下面关闭debugo01(MASTER)的MySQL
service mysql stop

#debugo01 keepalived log
an 21 20:00:23 debugo01 Keepalived[25202]: Stopping Keepalived v1.2.13 (10/15,2014)
Jan 21 20:00:23 debugo01 Keepalived_vrrp[25204]: VRRP_Instance(VI_1) sending 0 priority
Jan 21 20:00:23 debugo01 Keepalived_vrrp[25204]: VRRP_Instance(VI_1) removing protocol VIPs.

#debugo02 keepalived log
Jan 21 19:58:35 debugo02 Keepalived_vrrp[22065]: VRRP_Script(check_run) succeeded
Jan 21 20:00:24 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 21 20:00:24 debugo02 Keepalived_vrrp[22065]: VRRP_Group(VG1{) Syncing instances to MASTER state
Jan 21 20:00:25 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 21 20:00:25 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 21 20:00:25 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 10.6.2.200
Jan 21 20:00:25 debugo02 Keepalived_healthcheckers[22064]: Netlink reflector reports IP 10.6.2.200 added
Jan 21 20:00:30 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 10.6.2.200

#debugo01 keepalived log

an 21 20:00:23 debugo01 Keepalived[25202]: Stopping Keepalived v1.2.13 (10/15,2014)

Jan 21 20:00:23 debugo01 Keepalived_vrrp[25204]: VRRP_Instance(VI_1) sending 0 priority

Jan 21 20:00:23 debugo01 Keepalived_vrrp[25204]: VRRP_Instance(VI_1) removing protocol VIPs.

#debugo02 keepalived log

Jan 21 19:58:35 debugo02 Keepalived_vrrp[22065]: VRRP_Script(check_run) succeeded

Jan 21 20:00:24 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Transition to MASTER STATE

Jan 21 20:00:24 debugo02 Keepalived_vrrp[22065]: VRRP_Group(VG1{) Syncing instances to MASTER state

Jan 21 20:00:25 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Entering MASTER STATE

Jan 21 20:00:25 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) setting protocol VIPs.

Jan 21 20:00:25 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 10.6.2.200

Jan 21 20:00:25 debugo02 Keepalived_healthcheckers[22064]: Netlink reflector reports IP 10.6.2.200 added

Jan 21 20:00:30 debugo02 Keepalived_vrrp[22065]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth1 for 10.6.2.200

检查IP地址：

#debugo02
ip addr show
......
    inet 10.6.2.200/32 scope global eth1
......

#debugo02

ip addr show

......

inet 10.6.2.200/32 scope global eth1

......

切换成功^^

keepalived+MySQL双主实现高可用性

1. 配置MySQL Multi-Master Replication

2. 配置keepalived

3. 测试

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