author：JevonWei
版权声明：原创作品

主节点高可用

MHA是一款开源的MySQL的高可用程序，他为MySQL主从复制架构提供了automating master failover功能。MHA在监控到master节点故障时，会提升
其中拥有最新数据的slave节点成为新的master节点。在此期间，MHA会通过其他从节点获取额外信息来避免一致性方面的额问题。MHA还提供了master
节点切换功能，即按需切master/slave节点

MHA服务有两种角色，MHA Manager(管理节点)和HMA Node(数据节点)

MHA Manager：通常部署在一台独立机器上管理多个master/slave集群，每个master/slave集群称作一个application；
MHA node：运行在每台MySQL服务器上(master/slave/manager),他通过监控具备解析和清理logs功能的脚本来加快故障转移。

MHA组件

Manager节点-masterha_check_ssh:MHA依赖的SSH环境检测工具-masterha_check_repl:MySQL复制环境检测工具-masterha_manager:MHA服务主程序-masterha_check_status:MHA运行状态检测工具-masterha_master_monitor:MySQL master节点可用性检测工具-masterha_master_switch:master节点切换工具-masterha_conf_host:添加或删除配置节点-masterha_stop:关闭MHA服务的工具Node节点-save_binary_logs:保存和复制master的二进制日志-apply_diff_relay_logs:识别差异的中继日志事件并应用于其他slave-filter_mysqlbinlog:去除不必要的ROLLBACK事件(MHA已不在使用这个工具)-purge_relay_logs:清除中继日志(不会阻塞SQL线程)自定义扩展-sccondary_check_script:通过多条网络路由检测master的可用性-master_ip_failover_script:更新application使用的masterrip-shutdown_script：强制关闭master节点-report_script:发送报告-init_conf_load_script:加载初始化配置参数-master_ip_online_change_script:更新master节点ip地址

构建高可用HMA架构

节点角色

mysql-master 172.16.252.82
mysql-slave1 172.16.252.92
mysql-slave2 172.16.252.100
manager      172.16.252.67

配置各节点之间可以通过主机名通信

[root@manager  ~]# vim /etc/hosts
172.16.252.82 mysql-master
172.16.252.92 mysql-slave1
172.16.252.100 mysql-slave2
172.16.252.67 manager
其他各主机依次配置主机名解析文件

mysql-master

[root@mysql-master ~]# vim /etc/my.cnf.d/server.cnf
[mysqld]
server_id = 1
relay-log = relay-log
log-bin = master-log
skip_name_resolve = ON
innodb_file_per_table = ON
[root@mysql-master ~]# systemctl start mariadb[root@mysql-master ~]# mysql
授权一个有权限做主从复制的用户
MariaDB [(none)]> GRANT REPLICATION CLIENT,REPLICATION SLAVE ON *.* TO 'repluser'@'172.16.%.%' IDENTIFIED BY 'replpass';
MariaDB [(none)]> FLUSH PRIVILEGES;查看master节点的状态，记录二进制文件的位置信息，用于从节点的复制起点
MariaDB [(none)]> SHOW MASTER STATUS;
+-------------------+----------+--------------+------------------+
| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+-------------------+----------+--------------+------------------+
| master-log.000001 |      501 |              |                  |
+-------------------+----------+--------------+------------------+

mysql-slave1

[root@mysql-slave1 ~]# vim /etc/my.cnf.d/server.cnf
[mysqld]
server_id = 2
relay-log = relay-log
log-bin = master-log
skip_name_resolve = ON
innodb_file_per_table = ON
read_only = ON
relay_log_purge = OFF
[root@mysql-slave1 ~]# systemctl start mariadb   [root@mysql-slave ~]# mysql
MariaDB [mydb]> SHOW GLOBAL VARIABLES LIKE 'read_only';  \\查看数据库为只读
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | ON   |
+---------------+-------+
连接主节点数据库
MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='192.168.198.139',MASTER_USER='repluser',MASTER_PASSWORD='replpass',MASTER_LOG_FILE='master-log.000001',MASTER_LOG_POS=501;
启动从节点复制进程
MariaDB [(none)]> START SLAVE;
查看SLAVE节点的状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
连接manager的用户
MariaDB [(none)]> GRANT REPLICATION CLIENT,REPLICATION SLAVE ON *.* TO 'repluser'@'172.16.%.%' IDENTIFIED BY 'replpass';

mysql-slave2

root@mysql-slave2 ~]# vim /etc/my.cnf.d/server.cnf
[mysqld]
server_id = 3
relay-log = relay-log
log-bin = master-log
skip_name_resolve = ON
innodb_file_per_table = ON
read_only = ON
relay_log_purge = OFF
[root@mysql-slave2 ~]# systemctl start mariadb
[root@mysql-slave ~]# mysql
MariaDB [mydb]> SHOW GLOBAL VARIABLES LIKE 'read_only';  \\查看数据库为只读
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | ON   |
+---------------+-------+
连接主节点数据库
MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='192.168.198.139',MASTER_USER='repluser',MASTER_PASSWORD='replpass',MASTER_LOG_FILE='master-log.000001',MASTER_LOG_POS=501;
启动从节点复制进程
MariaDB [(none)]> START SLAVE;
查看SLAVE节点的状态
MariaDB [(none)]> SHOW SLAVE STATUS\G;
连接manager的用户
MariaDB [(none)]> GRANT REPLICATION CLIENT,REPLICATION SLAVE ON *.* TO 'repluser'@'172.16.%.%' IDENTIFIED BY 'replpass';

mysql-master(master/slave上都需有此用户权限来连接manager)

MariaDB [(none)]> GRANT ALL ON *.* TO 'mha'@'172.16.%.%' IDENTIFIED BY 'mhapass'；MariaDB [(none)]> GRANT REPLICATION CLIENT,REPLICATION SLAVE ON *.* TO 'repluser'@'172.16.%.%' IDENTIFIED BY 'replpass';

MHA安装

github官网下载manager到本地
[root@manager ~]# ls mha4mysql-node-0.56-0.el6.noarch.rpm mha4mysql-manager-0.56-0.el6.noarch.rpm
mha4mysql-manager-0.56-0.el6.noarch.rpm
mha4mysql-node-0.56-0.el6.noarch.rpm
[root@manager ~]# yum install ./mha4mysql-*   安装MHA程序包复制mha4mysql-node-0.56-0.el6.noarch.rpm程序包到各节点上
[root@manager ~]# scp mha4mysql-node-0.56-0.el6.noarch.rpm mysql-master:/root
[root@manager ~]# scp mha4mysql-node-0.56-0.el6.noarch.rpm mysql-slave1:/root
[root@manager ~]# scp mha4mysql-node-0.56-0.el6.noarch.rpm mysql-slave2:/rootmysql-master、mysql-slave1和mysql-slave2节点依次安装mha4mysql-node-0.56-0.el6.noarch.rpm程序包
[root@mysql-master ~]# yum -y install ./mha4mysql-node-0.56-0.el6.noarch.rpm
[root@mysql-slave1 ~]# yum -y install ./mha4mysql-node-0.56-0.el6.noarch.rpm
[root@mysql-slave2 ~]# yum -y install ./mha4mysql-node-0.56-0.el6.noarch.rpm

配置各节点之间SSH互信的通信环境
HMA

[root@manager ~]# ssh-keygen -t rsa -P ''  生成ssh秘钥文件
[root@manager ~]# ssh-copy-id -i .ssh/id_rsa.pub root@manager
[root@manager ~]# scp -p .ssh/id_rsa .ssh/authorized_leys root@mysql-master:/root/.ssh
[root@manager ~]# scp -p .ssh/id_rsa .ssh/authorized_leys root@mysql-slave1:/root/.ssh
[root@manager ~]# scp -p .ssh/id_rsa .ssh/authorized_leys root@mysql-slave2:/root/.ssh[root@mysql-master ~]# ssh -o StrictHostKeyChecking=no mysql-slave1 直接连接mysql-slave主机，无询问，无提示

初始化HMA

manager[root@manager ~]# mkdir /data/masterha[root@manager ~]# mkdir /data/masterha/app[root@manager ~]# mkdir /etc/masterha[root@manager ~]# vim /etc/masterha/app.cnf[server default]user=mhapassword=mhapass  \\node节点连接manager的用户manager_workdir=/data/masterha/appmanager_log=/data/masterha/app/manager.logremote_workdir=/data/masterha/appssh_user=rootrepl_user=repluserrepl_password=replpassping_interval=1[server1]hostname=172.16.252.82candidate_master=1[server2]hostname=172.16.252.92candidate_master=1[server3]hostname=172.16.252.100candidate_master=1

测试后端主机的集群

[root@manager ~]# masterha_check_repl --conf=/etc/masterha/app.cnf  

测试运行HMA程序

[root@manager ~]# masterha_manager --conf=/etc/masterha/app.cnf 

查看HMA集群的状态

[root@manager ~]# masterha_check_status