准备：
1.两台数据库主备环境搭建好，准备一台单独的mha_master，创建阿里云高可用虚拟ip：10.51.52.36
主：10.51.52.224 安装keepalived、mha_node
备：10.51.52.220 安装keepalived、mha_node
mha_master：10.51.52.223 安装mha_master、mha_node
2.keepalived，mha_master配置文件分别如下
主：
keepalived.conf
# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { root@localhost } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id internel_connection vrrp_skip_check_adv_addr #vrrp_strict vrrp_iptables vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_script chk_mysql { script /etc/keepalived/check_mysql.sh interval 1 weight -20 fall 3 rise 5 timeout 2 } vrrp_instance VI_1 { state BACKUP #设置ECS实例为backup状态 interface eth0 #设置网卡名，本示例配置为eth0 virtual_router_id 99 #定义分组ID，同一组ID相同 priority 100 #设置优先级，数字越大，优先级越高 advert_int 1 # preempt_delay 300 nopreempt unicast_src_ip 10.51.52.224 #设置ECS实例的私网IP地址 unicast_peer { 10.51.52.220 #同组中另一台ECS实例的私网IP地址 } authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.51.52.36 dev eth0 label eth0:0 #设置虚拟IP(Vip)的IP地址 } track_script { chk_mysql //执行检测脚本 } }
备:
keepalived.conf
# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { root@localhost } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id internel_connection vrrp_skip_check_adv_addr #vrrp_strict vrrp_iptables vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_script chk_mysql { script /etc/keepalived/check_mysql.sh interval 1 weight -20 fall 3 rise 5 timeout 2 } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 99 priority 90 advert_int 1 # preempt_delay 300 # nopreempt unicast_src_ip 10.51.52.220 unicast_peer { 10.51.52.224 } authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.51.52.36 dev eth0 label eth0:0 } track_script { chk_mysql } }
注意：
上面服务器的keepalived都设置为了BACKUP模式，在keepalived中2种模式，分别是master->backup模式和backup->backup模式。这两种模式有很大区别。在master->backup模式下，一旦主节点宕机，虚拟ip会自动漂移到从节点，当主节点修复后，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。在backup->backup模式下，当主节点故障后虚拟ip会自动漂移到从节点上，当原主节点恢复后，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。
检测脚本
check_mysql.sh
#!/bin/bash MYSQL=/opt/mysql/bin/mysql MYSQL_HOST=127.0.0.1 MYSQL_USER=xxx MYSQL_PASSWORD=xxx CHECK_TIME=3 #mysql is working MYSQL_OK is 1, mysql is down MYSQL_OK is 0 MYSQL_OK=1 function check_mysql_health(){ $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p$MYSQL_PASSWORD -e "show status;" >/dev/null 2>&1 if [ $? = 0 ]; then MYSQL_OK=1 else MYSQL_OK=0 fi return $MYSQL_OK } while [ $CHECK_TIME -ne 0 ] do let "CHECK_TIME -= 1" check_mysql_health if [ $MYSQL_OK = 1 ]; then CHECK_TIME=0 exit 0 fi if [ $MYSQL_OK -eq 0 ] && [ $CHECK_TIME -eq 0 ]; then pkill keepalived exit 1 fi done
mha_master配置如下：
[server default] user=root password=xxx manager_workdir=/etc/mha_master/app1 manager_log=/etc/mha_master/manager.log remote_workdir=/data/mha_master/app1 ssh_user=root repl_user=replication repl_password=xxxxxx ping_interval=1 master_binlog_dir=/opt/mysql/logs [server1] hostname=db1.danny.com ssh_port=22 candidate_master=1 [server2] hostname=db2.danny.com ssh_port=22 candidate_master=1
启动mha方式：
nohup masterha_manager --conf=/etc/mha_master/mha.cnf >>/etc/mha_master/manager.log 2&>1 &
3.添加阿里云虚拟IP绑定ES实例教程
https://help.aliyun.com/document_detail/184485.html?spm=5176.11182181.0.dexternal.b3254882uw8PRe#task-1938181
4.原理解析：
1）阿里云高可用虚拟IP+keepalived实现VIP主备绑定偏移，当keepalived通过检测脚本发现mysql服务宕了之后，自杀，备keepalived接替VIP并绑定至备机；
2）此例mha检测对象为两台mysql，一主一备，当检测一台mysql服务出问题后可以通过VIP将请求切换至备机。
3）此例使用keepalived实现vip偏移，能实现的原因是备机只有一台，主机服务挂了后，能确定vip肯定能漂移至新的主机。
4）缺点：
master主机宕机后无法切换，以及无法补全binlog，但是master的mysqld进程crash后，还是可以切换成功，以及补全binlog的。