背景
MySQL的高可用方案一般有如下几种：
keepalived+双主，MHA，MMM，Heartbeat+DRBD，PXC，Galera Cluster
比较常用的是keepalived+双主，MHA和PXC。
对于小公司，一般推荐使用keepalived+双主，便于维护。
环境
mysql双主配置
1. 修改配置文件
master1中有关复制的配置如下：
[mysqld]log-bin=mysql-binserver-id=1log_slave_updates=1
master2中有关复制的配置如下：
[mysqld]log-bin=mysql-binserver-id=2log_slave_updates=1read_only=1
改完之后把两个数据库都重启了
2. 创建复制用户
master1中创建：
CREATE USER 'repl'@'10.1.80.114' IDENTIFIED BY 'Mysql@2019';GRANT REPLICATION SLAVE ON *.* TO 'repl'@'10.1.80.114';
master2中创建：
CREATE USER 'repl'@'10.1.80.113' IDENTIFIED BY 'Mysql@2019';GRANT REPLICATION SLAVE ON *.* TO 'repl'@'10.1.80.113';
3. 执行CHANGE MASTER TO语句
因是从头搭建MySQL主从复制集群，所以不需要获取全局读锁来得到二进制日志文件的位置，直接根据show master status的输出来确认。
master1上执行：
CHANGE MASTER TO MASTER_HOST='10.1.80.114', MASTER_USER='repl', MASTER_PASSWORD='Mysql@2019', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=154;
master2上执行：
CHANGE MASTER TO MASTER_HOST='10.1.80.113', MASTER_USER='repl', MASTER_PASSWORD='Mysql@2019', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=154;
4. 分别在两个节点上执行start slave;语句
并通过show slave status\G查看复制是否搭建成功。
出现如下内容说明成功。
5、数据同步测试
在两侧插入数据发现正常同步。
keepalived配置
1、安装依赖包
yum install gcc yum install openssl*
2、下载软件，解压编译
#下载wget http://www.keepalived.org/software/keepalived-2.0.10.tar.gz#解压tar -zxvf keepalived-2.0.10.tar.gz #编译./configure --prefix=/keepalived
3、初始化以及启动
# keepalived启动脚本变量引用文件，默认文件路径是/etc/sysconfig/，也可以不做软链接，直接修改启动脚本中文件路径即可（安装目录下）[root@localhost /]# cp /keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived # 将keepalived主程序加入到环境变量（安装目录下）[root@localhost /]# cp /keepalived/sbin/keepalived /usr/sbin/keepalived # keepalived启动脚本（源码目录下），放到/etc/init.d/目录下就可以使用service命令便捷调用[root@localhost /]# cp /tmp/keepalived-2.0.10/keepalived/etc/init.d/keepalived /etc/init.d/keepalived # 将配置文件放到默认路径下[root@localhost /]# mkdir /etc/keepalived[root@localhost /]# cp /keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf#加为系统服务：chkconfig --add keepalived#开机启动：chkconfig keepalived on#查看开机启动的服务：chkconfig --list#启动、关闭、重启service keepalived start|stop|restart
4、修改配置文件
master1
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived global_defs {notification_email {ops@wangshibo.cntech@wangshibo.cn} notification_email_from ops@wangshibo.cnsmtp_server 127.0.0.1 smtp_connect_timeout 30router_id MASTER-HA} vrrp_script chk_mysql_port { #检测mysql服务是否在运行。有很多方式，比如进程，用脚本检测等等 script "/keepalived/chk_mysql.sh" #这里通过脚本监测 interval 2 #脚本执行间隔，每2s检测一次 weight -5 #脚本结果导致的优先级变更，检测失败（脚本返回非0）则优先级 -5 fall 2 #检测连续2次失败才算确定是真失败。会用weight减少优先级（1-255之间） rise 1 #检测1次成功就算成功。但不修改优先级} vrrp_instance VI_1 { state MASTER interface eth2 #指定虚拟ip的网卡接口 mcast_src_ip 10.1.80.113 virtual_router_id 51 #路由器标识，MASTER和BACKUP必须是一致的 priority 101 #数字越大，优先级越高，同一个vrrp_instance下，MASTER的优先级必须大于BACKUP的优先级。这样MASTER故障恢复后，就可以将VIP资源再次抢回来 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.1.80.119 } track_script { chk_mysql_port }} 编写切换脚本。KeepAlived做心跳检测，如果Master的MySQL服务挂了(3306端口挂了),那么它就会选择自杀。
Slave的KeepAlived通过心跳检测发现这个情况，就会将VIP的请求接管
vi chk_mysql.sh
#!/bin/bashcounter=$(netstat -na|grep "LISTEN"|grep "3306"|wc -l)if [ "${counter}" -eq 0 ]; then service keepalived stopfi chmod 755 chk_mysql.sh
启动keepalived服务。
master2
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived global_defs {notification_email {ops@wangshibo.cntech@wangshibo.cn} notification_email_from ops@wangshibo.cnsmtp_server 127.0.0.1 smtp_connect_timeout 30router_id MASTER-HA} vrrp_script chk_mysql_port { script "/keepalived/chk_mysql.sh" interval 2 weight -5 fall 2 rise 1 } vrrp_instance VI_1 { state BACKUP interface eth2 mcast_src_ip 10.1.80.114 virtual_router_id 51 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.1.80.119 } track_script { chk_mysql_port }} vi chk_mysql.sh
#!/bin/bashcounter=$(netstat -na|grep "LISTEN"|grep "3306"|wc -l)if [ "${counter}" -eq 0 ]; then service keepalived stopfi chmod 755 chk_mysql.sh
查看网卡
