linux复盘：keepalived+mysql双主构建高可用数据库

关于MySQL-HA，目前有多种解决方案，比如heartbeat、drbd、mmm、共享存储，但是它们各有优缺点。heartbeat、drbd配置较为复杂，需要自己写脚本才能实现MySQL自动切换，对于不会脚本语言的人来说，这无疑是一种脑裂问题；对于mmm，生产环境中很少有人用，且mmm管理端需要单独运行一台服务器上，要是想实现高可用，就得对mmm管理端做HA，这样无疑又增加了硬件开支；对于共享存储，MySQL数据还是放在本地较为安全，存储设备毕竟存在单点隐患。

使用MySQL双master+keepalived是一种非常好的解决方案，在MySQL-HA环境 中，MySQL互为主从关系，这样就保证了两台MySQL数据的一致性，然后用keepalived实现虚拟IP，通过keepalived自带的服务监 控功能来实现MySQL故障时自动切换。

机器ip及版本：

MySQL-VIP	    192.168.230.200
MySQL-master1	192.168.230.130
MySQL-master2	192.168.230.152

OS版本：CentOS 7.3
MySQL版本：5.6
Keepalived版本：1.2.7

第一步关闭防火墙：

selinux永久关闭 vi /etc/selinux/config selinux修改此处为disabled，reboot重启生效

关闭firewalld：
systemctl disable firewalled 先暂停，不让开机启动

systemctl stop firewalld 关闭服务

关闭iptables：
systemctl disable iptables

systemctl stop iptables

第二步mysql双主配置：

两台MySQL均如要开启binlog日志功能，开启方法：在MySQL配置文件[MySQLd]段中加上log-bin=MySQL-bin选项 两台MySQL的server-ID不能一样，默认情况下两台MySQL的serverID都是1，需将其中一台修改为2即可

Master1配置：

vim /etc/my.cnf

[mysqld]
datadir = /data/mysql
socket = /tmp/mysql.sock
server_id = 1                 #指定server-id，必须保证主从服务器的server-id不同
auto_increment_increment = 2  #设置主键单次增量
auto_increment_offset = 1     #设置单次增量中主键的偏移量
log-bin = mysql-bin           #创建主从需要开启log-bin日志文件
log-slave-updates             #把更新的日志写到二进制文件（binlog）中

master2配置：

vim /etc/my.cnf

[mysqld]
datadir = /data/mysql
socket = /tmp/mysql.sock
server_id = 2                 #指定server-id，必须保证主从服务器的server-id不同
auto_increment_increment = 2  #设置主键单次增量
auto_increment_offset = 2     #设置单次增量中主键的偏移量
log-bin = mysql-bin           #创建主从需要开启log-bin日志文件
log-slave-updates             #把更新的日志写到二进制文件（binlog）中

重要参数：

log-slave-updates = true #将复制事件写入binlog,一台服务器做主库又做从库此选项必须要开启

重启两台server的mysql服务：

/etc/init.d/mysqld restart

将192.168.230.130设为192.168.230.152的主服务器：

mysql -uroot

mysql> grant replication slave on *.* to 'repl'@'192.168.230.152' identified by 'zhangduanya';

mysql> flush privileges;

将192.168.230.152设为192.168.230.130的主服务器：

mysql -uroot

mysql> grant replication slave on *.* to 'repl'@'192.168.230.130' identified by 'zhangduanya';

mysql> flush privileges;

在Mysql-Master1上操作：

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000003 |      421 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql> change master to master_host='192.168.230.152',master_port=3306,master_user='repl',master_password='zhangduanya',master_log_file='mysql-bin.000002',master_log_pos=120;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

mysql>  show slave status\G
yes
yes

在Mysql-Master2上操作：

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000002 |      120 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql> change master to master_host='192.168.230.130',master_port=3306,master_user='repl',master_password='zhangduanya',master_log_file='mysql-bin.000003',master_log_poos=421;
Query OK, 0 rows affected, 2 warnings (0.06 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

mysql>  show slave status\G
yes
yes

##注意如果开始就启动了start slave，在操作同步的时候需要先停止它，stop slave

以上把双主做完了下来搞keepalived：

192.168.230.130服务器上keepalived安装及配置 安装keepalived

当然安装推荐源码包安装，或者懒了就yum直接安装

yum install -y keepalived

或者

yum install -y pcre-devel openssl-devel popt-devel   #安装依赖包

cd /usr/local/src

wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz 
tar -zxvf keepalived-1.2.7.tar.gz

cd ./keepalived-1.2.7

./configure --prefix=/usr/local/keepalived

make  &&  make install

echo $?

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/

chmod +x /etc/init.d/keepalived

chkconfig --add keepalived

chkconfig keepalived on

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

mkdir /etc/keepalived/

cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

然后配置130的keepalived：

vi /etc/keepalived/keepalived.conf

vi /etc/keepalived/keepalived.conf
#写入以下内容
! Configuration File forkeepalived
global_defs {
notification_email {
test@sina.com
}
notification_email_from  admin@admin.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id MYSQL_HA      #标识，双主相同
}
vrrp_instance VI_1 {
state BACKUP           #两台都设置BACKUP
interface ens33
virtual_router_id 51       #主备相同
priority 100   #优先级，另一台改为90
advert_int 1
nopreempt  #不抢占，只在优先级高的机器上设置即可，优先级低的机器不设置
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.230.200
}
}

virtual_server 192.168.230.200 3306 {
delay_loop 2   #每个2秒检查一次real_server状态
lb_algo wrr   #LVS算法
lb_kind DR    #LVS模式
persistence_timeout 60   #会话保持时间
protocol TCP
real_server 192.168.230.130 3306 {
weight 3
notify_down /usr/local/keepalived/mysql.sh  #检测到服务down后执行的脚本
TCP_CHECK {
connect_timeout 10    #连接超时时间
nb_get_retry 3       #重连次数
delay_before_retry 3   #重连间隔时间
connect_port 3306   #健康检查端口
}
}
}

编写检测服务down后所要执行的脚本（添加/usr/local/keepalived/mysql.sh）

vim  /usr/local/keepalived/mysql.sh

#!/bin/bash
pkill keepalived
sleep  10
/etc/init.d/keepalived start  >/dev/null

----------
# chmod +x /usr/local/keepalived/mysql.sh

注：此脚本是上面配置文件notify_down选项所用到的，keepalived使用notify_down选项来检查real_server 的服务状态，当发现real_server服务故障时，便触发此脚本；我们可以看到，脚本就一个命令，通过pkill keepalived强制杀死keepalived进程，从而实现了MySQL故障自动转移。另外，我们不用担心两个MySQL会同时提供数据更新操作， 因为每台MySQL上的keepalived的配置里面只有本机MySQL的IP+VIP，而不是两台MySQL的IP+VIP。

启动keepalived

/etc/init.d/keepalived start

192.168.230.152上keepalived安装及配置 安装keepalived，安装方法参照192.168.230.130的安装方法 配置keepalived 这台配置和上面基本一样，但有三个地方不同：优先级为90、无抢占设置、real_server为本机IP

vi /etc/keepalived/keepalived.conf

vi /etc/keepalived/keepalived.conf
#写入以下内容
! Configuration File forkeepalived
global_defs {
notification_email {
test@sina.com
}
notification_email_from  admin@admin.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id MYSQL_HA      #标识，双主相同
}
vrrp_instance VI_1 {
state BACKUP           #两台都设置BACKUP
interface ens33
virtual_router_id 51       #主备相同
priority 90   #优先级，此处应改为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.230.200
}
}

virtual_server 192.168.230.200 3306 {
delay_loop 2   #每个2秒检查一次real_server状态
lb_algo wrr   #LVS算法
lb_kind DR    #LVS模式
persistence_timeout 60   #会话保持时间
protocol TCP
real_server 192.168.230.152 3306 {
weight 3
notify_down /usr/local/keepalived/mysql.sh  #检测到服务down后执行的脚本
TCP_CHECK {
connect_timeout 10    #连接超时时间
nb_get_retry 3       #重连次数
delay_before_retry 3   #重连间隔时间
connect_port 3306   #健康检查端口
}
}
}

编写检测服务down后所要执行的脚本（添加/usr/local/keepalived/mysql.sh）

然后还是杀掉mysql的脚本：

vim  /usr/local/keepalived/mysql.sh

#!/bin/bash
pkill keepalived
sleep  10
/etc/init.d/keepalived start  >/dev/null

----------
# chmod +x /usr/local/keepalived/mysql.sh

启动keepalived

/etc/init.d/keepalived start

好了配置完了，测试

如果服务器宕机，Keepalived服务肯定回停止工作，所以在此通过开/关Keepalived来模拟宕机状态：

宕机前：

查看master服务器IP状态：
ip add
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:8a:1b:5c brd ff:ff:ff:ff:ff:ff
inet 192.168.230.130/24 brd 192.168.8.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.230.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::65d2:adc:20d3:8c74/64 scope link
valid_lft forever preferred_lft forever

查看backup服务器IP状态：
ip add
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:af:b7:9f brd ff:ff:ff:ff:ff:ff
inet 192.168.230.152/24 brd 192.168.8.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::76c1:b882:4f26:608c/64 scope link
valid_lft forever preferred_lft forever

说明： 此时VIP在master服务器上，说明有master对外提供服务。
vip也绑定在master这台机器上

master服务器宕机后：

此时vip到了152机器上，此时有backup服务器接管master服务器对外提供服务。

恢复master服务器Keepalived服务，此时VIP并没有回到master服务器上，原因是master在进行Keepalived的时候加入了参数nopreemt。

注意：原因是nopreemt不抢占，只在优先级高的机器上设置即可，优先级低的机器不设置 ，咱们给130这个优先级高的设置不抢占资源，所以vip停留在152上提供服务