Linux学习-MySQL的主从复制高可用性解决方案MHA

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一、MHA简介

1、MHA

 Master High Availability,对主节点进行监控,可实现自动故障转移至其它从节点;通过提升某一从节点为新的主节点,基于主从复制实现,还需要客户端配合实现,目前MHA主要支持一主多从的架构,要搭建MHA,要求一个复制集群中必须最少有三台 数据库服务器,一主二从,即一台充当master,一台充当备用master,另外一台充当从库。

2、MHA集群架构

MHA集群

3、MHA的工作原理

 (1) 从宕机崩溃的master保存二进制日志事件(binlog events)
 (2) 识别含有最新更新的slave
 (3) 应用差异的中继日志(relay log)到其他的slave
 (4) 应用从master保存的二进制日志事件(binlog events)
 (5) 提升一个slave为新的master
 (6) 使其他的slave连接新的master进行复制

4、MHA软件组成

 (1) Manager 工具包
  Manager工具包主要包含以下几个工具:    
   masterha_check_ssh    检查MHA的SSH配置状况
   masterha_check_repl    检查mysql复制状况
   masterha_manger       启动MHA         
   masterha_check_status   检测当前MHA运行状态
   masterha_master_monitor  检测master是否宕机
   masterha_master_switch   故障转移(自动或手动)
   masterha_conf_host     添加或删除配置的server信息
 (2) Node 工具包
  Node工具包:(这些工具通常由MHA Manager的脚本触发,无需人为操作)主要包括以下几个工具:
   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将其差异的事件应用于其他的slave
   filter_mysqlbinlog      去除不必要的ROLLBACK事件(MHA已不再使用此工具)
   purge_relay_logs     清除中继日志(不会阻塞SQL线程)
  注意:为了尽可能的减少主库硬件损坏宕机造成的数据丢失,因此在配置MHA的同时建议配置成MySQL 5.5的半同步复制
 (3) 自定义扩展
  secondary_check_script   通过多条网络路由检测master的可用性
  master_ip_ailover_script   更新Application使用的masterip
  shutdown_script        强制关闭master节点
   report_script         发送报告
  init_conf_load_script      加载初始配置参数
  master_ip_online_change_script   更新master节点ip地址
 (4) 配置文件:
  global配置:为各application提供默认配置
  application配置:为每个主从复制集群

二、实验环境

 主机:4台,一台MHA Manager (192.168.214.17),三台主从复制架构(一主多从),master (192.168.214.27),slave1 (192.168.214.37),slave2 (192.168.214.47)

 系统:CentOS7.6

 数据库:mariadb-server-5.5.60(光盘yum源)

 MHA软件包:mha4mysql-manager-0.56,mha4mysql-node-0.56

三、相关步骤

 1、三台主从节点主点先安装mariadb数据库,使用光盘yum源

[root@centos7-27 ~]# yum install -y mariadb-server
[root@centos7-37 ~]# yum install -y mariadb-server
[root@centos7-47 ~]# yum install -y mariadb-server

 2、准备MHA软件包,MHA Manager节点需要mha4mysql-manager和mha4mysql-node,其它三个节点只需要mha4mysql-node

[root@centos7-17 ~]# ll mha4mysql*
-rw-r--r-- 1 root root 87119 Dec  9 10:32 mha4mysql-manager-0.56-0.el6.noarch.rpm
-rw-r--r-- 1 root root 36326 Dec  9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm
[root@centos7-27 ~]# ll mha4mysql*
-rw-r--r-- 1 root root 36326 Dec  9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm
[root@centos7-37 ~]# ll mha4mysql*
-rw-r--r-- 1 root root 36326 Dec  9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm
[root@centos7-47 ~]# ll mha4mysql*
-rw-r--r-- 1 root root 36326 Dec  9 10:32 mha4mysql-node-0.56-0.el6.noarch.rpm

 3、安装MHA软件包,MHA Manager节安装mha4mysql-manager时需要依赖epel源,这里使用阿里云的epel源

[root@centos7-17 ~]# cat /etc/yum.repos.d/base.repo
[development]
name=dvdbase repo
baseurl=file:///mnt/cdrom/
enabled=1
gpgcheck=1
gpgkey=file:///mnt/cdrom/RPM-GPG-KEY-CentOS-7

[aliyunEpel]
name=aliyun epel
baseurl=https://mirrors.aliyun.com/epel/$releasever/$basearch
enabled=1
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/epel/RPM-GPG-KEY-EPEL-$releasever
[root@centos7-17 ~]# yum install -y mha4mysql*
[root@centos7-27 ~]# yum install -y mha4mysql-node-0.56-0.el6.noarch.rpm
[root@centos7-37 ~]# yum install -y mha4mysql-node-0.56-0.el6.noarch.rpm
[root@centos7-47 ~]# yum install -y mha4mysql-node-0.56-0.el6.noarch.rpm

 4、配置主从复制(一主多从)

  1). master节点

[root@centos7-27 ~]# vim /etc/my.cnf
[mysqld]
server-id=27    #添加此项
bin-log    #添加此项
skip_name_resolve=1    #添加此项
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d 
[root@centos7-27 ~]# systemctl start mariadb
[root@centos7-27 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MariaDB connection id is 2
Server version: 5.5.60-MariaDB MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type \'help;\' or \'\\h\' for help. Type \'\\c\' to clear the current input statement.

MariaDB [(none)]> show master logs;
+--------------------+-----------+
| Log_name           | File_size |
+--------------------+-----------+
| mariadb-bin.000001 |       245 |
+--------------------+-----------+
1 row in set (0.00 sec)

MariaDB [(none)]> grant replication slave on *.* to repluser@\'192.168.214.%\' identified by \'centos\';    #添加主从复制用户
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> grant all on *.* to mhauser@\'192.168.214.%\' identified by \'mhauser\';    #添加mha管理用户
Query OK, 0 rows affected (0.00 sec)

  2). slave节点,两台节点的配置一样,以slave1(192.168.214.37)为例

[root@centos7-37 ~]# cat /etc/my.cnf
[mysqld]
server-id=37    #添加此项,slave2上的值记得改成47
log_bin    #添加此项
read-only    #添加此项
skip_name_resolve=1    #添加此项
relay_log_purge=0    #添加此项,是否清除中继日志,默认开启,这里把它关闭,因为需要用到中继日志
...以下省略
[root@centos7-37 ~]# systemctl start mariadb [root@centos7
-37 ~]# mysql Welcome to the MariaDB monitor. Commands end with ; or \\g. Your MariaDB connection id is 6 Server version: 5.5.60-MariaDB MariaDB Server Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type \'help;\' or \'\\h\' for help. Type \'\\c\' to clear the current input statement. MariaDB [(none)]> CHANGE MASTER TO #配置连接主节点的信息 -> MASTER_HOST=\'192.168.214.27\', #主节点IP -> MASTER_USER=\'repluser\', #用于复制的账号 -> MASTER_PASSWORD=\'centos\', #密码 -> MASTER_LOG_FILE=\'mariadb-bin.000001\', #要复制的二进制日志 -> MASTER_LOG_POS=245; #开始复制的二进制日志的位置 Query OK, 0 rows affected (0.01 sec) MariaDB [(none)]> start slave; #开启复制线程 Query OK, 0 rows affected (0.00 sec) MariaDB [(none)]> show slave status\\G; #可用于查看开启状态

  5、配置MHA Manager主机和其它三台主机的基于key验证的ssh服务

[root@centos7-17 ~]# ssh-keygen  #生成密钥
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:F8VxSwWdphlQLd1J9csOHEW932/ZIhi6agC2BxDJ89A root@centos7.localdomain
The key\'s randomart image is:
+---[RSA 2048]----+
|oo.        o=oOBO|
|o+ E       ..=.B=|
| .+       .  .B o|
|  +.       ..oo..|
| . +    S .  o oo|
|  . o    ..   o o|
|   . .   . o   .+|
|      . . . . ..+|
|     .....   . o |
+----[SHA256]-----+
[root@centos7-17 ~]# ls -a .ssh
.  ..  id_rsa  id_rsa.pub  known_hosts
#拷贝公钥到本地,然后把本地的.ssh文件夹复制到其它三台主机的/root/目录下
#即可实现四台主机之前相互之间都可以互机登录而不用输密码
#如果只是配置MHA Manage登陆其它三台,只需要用以下命令
# ssh-copy-id -i  /root/.ssh/id_rsa.pub root@192.168.214.27 
[root@centos7-17 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.214.17  
[root@centos7-17 ~]# scp -r .ssh root@192.168.214.27:/root/
[root@centos7-17 ~]# scp -r .ssh root@192.168.214.37:/root/
[root@centos7-17 ~]# scp -r .ssh root@192.168.214.47:/root/

 6、配置MHA Manager节点的配置文件

[root@centos7-17 ~]# mkdir /etc/mha/
[root@centos7-17 ~]# vim /etc/mha/app1.cnf
[server default]
user=mhauser    #管理用户
password=mhauser    #密码
manager_workdir=/data/mastermha/app1/
manager_log=/data/mastermha/app1/manager.log 
remote_workdir=/data/mastermha/app1/ 
ssh_user=root  #ssh用户
repl_user=repluser #复制用户
repl_password=centos  #密码
ping_interval=1    #监测master的时间1s

[server1]
hostname=192.168.214.27
candidate_master=1    #此选项表示优先使用此主节点
[server2]
hostname=192.168.214.37
candidate_master=1
[server3]
hostname=192.168.214.47

 7、验证与启动

[root@centos7-17 ~]# masterha_check_ssh --conf=/etc/mha/app1.cnf  #验证ssh
[root@centos7-17 ~]# masterha_check_repl --conf=/etc/mha/app1.cnf  #验证主从复制
[root@centos7-17 ~]# masterha_manager --conf=/etc/mha/app1.cnf  #启动

  注意:masterha_manager --conf=/etc/mha/app1.cnf 这种启动是一次性的(完成一次切换后就退出了),且只是在当前会话;建议后台启动运行:nohup masterha_manager --conf=/etc/mha/app1.cnf > mha.log

 8、测试当mater节点断开时,主从的切换

[root@centos7-27 ~]# systemctl stop mariadb  #关闭主节点数据库服务
[root@centos7-37 ~]# mysql  
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MariaDB connection id is 21
Server version: 5.5.60-MariaDB MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type \'help;\' or \'\\h\' for help. Type \'\\c\' to clear the current input statement.

MariaDB [(none)]> show slave status\\G;   #查询为空,说明slave1节点已提升为主节点
Empty set (0.00 sec)
MariaDB [(none)]> show variables like \'read_only\'; #slave1节点的read-only选项也关闭了
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| read_only     | OFF   |
+---------------+-------+
1 row in set (0.00 sec)

[root@centos7-47 ~]# mysql 
MariaDB [(none)]> show slave status\\G;   #在slave2上查看
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.214.37  #主节点变为了slave1
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mariadb-bin.000001
          Read_Master_Log_Pos: 245
               Relay_Log_File: mariadb-relay-bin.000002
                Relay_Log_Pos: 531
        Relay_Master_Log_File: mariadb-bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
...以下省略

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