如何利用MHA+ProxySQL实现读写分离和负载均衡

摘要：本文分享一下“MHA+中间件ProxySQL”如何来实现读写分离+负载均衡的相关知识。

本文分享自华为云社区《MySQL高可用架构MHA+ProxySQL实现读写分离和负载均衡》，作者：小麦苗DB宝。

一、MHA+ProxySQL架构

我们都知道，MHA（Master High Availability Manager and tools for MySQL）目前在MySQL高可用方面是一个相对成熟的解决方案，是一套作为MySQL高可用性环境下故障切换和主从提升的高可用软件。它的架构是要求一个MySQL复制集群必须最少有3台数据库服务器，一主二从，即一台充当Master，一台充当备用Master，另一台充当从库。但是，如果不连接任何外部的数据库中间件，那么就会导致所有的业务压力流向主库，从而造成主库压力过大，而2个从库除了本身的IO和SQL线程外，无任何业务压力，会严重造成资源的浪费。因此，我们可以把MHA和ProxySQL结合使用来实现读写分离和负载均衡。所有的业务通过中间件ProxySQL后，会被分配到不同的MySQL机器上。从而，前端的写操作会流向主库，而读操作会被负载均衡的转发到2个从库上。

MHA+ProxySQL架构如下图所示：

https://cdn.jsdelivr.net/gh/lhrbest/pic/img/20210416111756.png

二、快速搭建MHA环境

2.1 下载MHA镜像

• 小麦苗的Docker Hub的地址：https://hub.docker.com/u/lhrbest

-- 下载镜像

docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-master1-ip131
docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-slave1-ip132
docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-slave2-ip133
docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-monitor-ip134

-- 重命名镜像

docker tag     registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-master1-ip131  lhrbest/mha-lhr-master1-ip131
docker tag    registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-slave1-ip132   lhrbest/mha-lhr-slave1-ip132 
docker tag    registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-slave2-ip133   lhrbest/mha-lhr-slave2-ip133 
docker tag    registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-monitor-ip134  lhrbest/mha-lhr-monitor-ip134

一共4个镜像，3个MHA Node，一个MHA Manager，压缩包大概3G，下载完成后：

[root@lhrdocker ~]# docker images | grep mha
registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-monitor-ip134          latest              7d29597dc997        14 hours ago        1.53GB
registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-slave2-ip133           latest              d3717794e93a        40 hours ago        4.56GB
registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-slave1-ip132           latest              f62ee813e487        40 hours ago        4.56GB
registry.cn-hangzhou.aliyuncs.com/lhrbest/mha-lhr-master1-ip131          latest              ae7be48d83dc        40 hours ago        4.56GB

2.2 编辑yml文件，创建MHA相关容器

编辑yml文件，使用docker-compose来创建MHA相关容器，注意docker-compose.yml文件的格式，对空格、缩进、对齐都有严格要求：

# 创建存放yml文件的路径
mkdir -p /root/mha

# 编辑文件/root/mha/docker-compose.yml
cat > /root/mha/docker-compose.yml <<"EOF"
version: '3.8'

services:
  MHA-LHR-Master1-ip131:
    container_name: "MHA-LHR-Master1-ip131"
    restart: "always"
    hostname: MHA-LHR-Master1-ip131
    privileged: true
    image: lhrbest/mha-lhr-master1-ip131
    ports:
      - "33131:3306"
      - "2201:22"
    networks:
      mhalhr:
        ipv4_address: 192.168.68.131

  MHA-LHR-Slave1-ip132:
    container_name: "MHA-LHR-Slave1-ip132"
    restart: "always"
    hostname: MHA-LHR-Slave1-ip132
    privileged: true
    image: lhrbest/mha-lhr-slave1-ip132
    ports:
      - "33132:3306"
      - "2202:22"
    networks:
      mhalhr:
        ipv4_address: 192.168.68.132

  MHA-LHR-Slave2-ip133:
    container_name: "MHA-LHR-Slave2-ip133"
    restart: "always"
    hostname: MHA-LHR-Slave2-ip133
    privileged: true
    image: lhrbest/mha-lhr-slave2-ip133
    ports:
      - "33133:3306"
      - "2203:22"
    networks:
      mhalhr:
        ipv4_address: 192.168.68.133

  MHA-LHR-Monitor-ip134:
    container_name: "MHA-LHR-Monitor-ip134"
    restart: "always"
    hostname: MHA-LHR-Monitor-ip134
    privileged: true
    image: lhrbest/mha-lhr-monitor-ip134
    ports:
      - "33134:3306"
      - "2204:22"
    networks:
      mhalhr:
        ipv4_address: 192.168.68.134

networks:
  mhalhr:
    name: mhalhr
    ipam:
      config:
         - subnet: "192.168.68.0/16"

EOF

2.3 安装docker-compose软件（若已安装，可忽略）

• 安装 Docker Compose官方文档：https://docs.docker.com/compose/

• 编辑docker-compose.yml文件官方文档：https://docs.docker.com/compose/compose-file/

[root@lhrdocker ~]# curl --insecure -L https://github.com/docker/compose/releases/download/1.28.4/docker-compose-Linux-x86_64 -o /usr/local/bin/docker-compose
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   638  100   638    0     0    530      0  0:00:01  0:00:01 --:--:--   531
100 11.6M  100 11.6M    0     0  1994k      0  0:00:06  0:00:06 --:--:-- 2943k
[root@lhrdocker ~]# chmod +x /usr/local/bin/docker-compose
[root@lhrdocker ~]# docker-compose -v
docker-compose version 1.28.4, build cabd5cfb

2.4 创建MHA容器

# 启动mha环境的容器，一定要进入文件夹/root/mha/后再操作
-- docker rm -f MHA-LHR-Master1-ip131 MHA-LHR-Slave1-ip132 MHA-LHR-Slave2-ip133 MHA-LHR-Monitor-ip134
[root@lhrdocker ~]# cd /root/mha/
[root@lhrdocker mha]#
[root@lhrdocker mha]# docker-compose up -d
Creating network "mhalhr" with the default driver
Creating MHA-LHR-Monitor-ip134 ... done
Creating MHA-LHR-Slave2-ip133  ... done
Creating MHA-LHR-Master1-ip131 ... done
Creating MHA-LHR-Slave1-ip132  ... done
[root@docker35 ~]# docker ps | grep "mha\|COMMAND" 
CONTAINER ID        IMAGE                           COMMAND                  CREATED             STATUS              PORTS                                                                                           NAMES
2978361198b7        lhrbest/mha-lhr-master1-ip131   "/usr/sbin/init"         2 minutes ago       Up 2 minutes        16500-16599/tcp, 0.0.0.0:2201->22/tcp, 0.0.0.0:33131->3306/tcp                                  MHA-LHR-Master1-ip131
a64e2e86589c        lhrbest/mha-lhr-slave1-ip132    "/usr/sbin/init"         2 minutes ago       Up 2 minutes        16500-16599/tcp, 0.0.0.0:2202->22/tcp, 0.0.0.0:33132->3306/tcp                                  MHA-LHR-Slave1-ip132
d7d6ce34800b        lhrbest/mha-lhr-monitor-ip134   "/usr/sbin/init"         2 minutes ago       Up 2 minutes        0.0.0.0:2204->22/tcp, 0.0.0.0:33134->3306/tcp                                                   MHA-LHR-Monitor-ip134
dacd22edb2f8        lhrbest/mha-lhr-slave2-ip133    "/usr/sbin/init"         2 minutes ago       Up 2 minutes        16500-16599/tcp, 0.0.0.0:2203->22/tcp, 0.0.0.0:33133->3306/tcp                                  MHA-LHR-Slave2-ip133

2.5 主库131添加VIP

# 进入主库131
docker exec -it MHA-LHR-Master1-ip131 bash

# 添加VIP135
/sbin/ifconfig eth0:1 192.168.68.135/24
ifconfig

# 如果删除的话
ip addr del 192.168.68.135/24 dev eth1

添加完成后：

[root@MHA-LHR-Master1-ip131 /]# ifconfig
eth0: flags=4163  mtu 1500
        inet 192.168.68.131  netmask 255.255.0.0  broadcast 192.168.255.255
        ether 02:42:c0:a8:44:83  txqueuelen 0  (Ethernet)
        RX packets 220  bytes 15883 (15.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 189  bytes 17524 (17.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0:1: flags=4163  mtu 1500
        inet 192.168.68.135  netmask 255.255.255.0  broadcast 192.168.68.255
        ether 02:42:c0:a8:44:83  txqueuelen 0  
lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 5  bytes 400 (400.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5  bytes 400 (400.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 
# 管理节点已经可以ping通VIP了
[root@MHA-LHR-Monitor-ip134 /]# ping 192.168.68.135
PING 192.168.68.135 (192.168.68.135) 56(84) bytes of data.
64 bytes from 192.168.68.135: icmp_seq=1 ttl=64 time=0.172 ms
64 bytes from 192.168.68.135: icmp_seq=2 ttl=64 time=0.076 ms
^C
--- 192.168.68.135 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.076/0.124/0.172/0.048 ms

到这一步就可以验证主从复制是否正确，若正确，则可以直接测试MHA了。

mysql -uroot -plhr -h192.168.68.131 -P3306
show slave hosts;
mysql> show slave hosts;
+-----------+----------------+------+-----------+--------------------------------------+
| Server_id | Host           | Port | Master_id | Slave_UUID                           |
+-----------+----------------+------+-----------+--------------------------------------+
| 573306133 | 192.168.68.133 | 3306 | 573306131 | d391ce7e-aec3-11ea-94cd-0242c0a84485 |
| 573306132 | 192.168.68.132 | 3306 | 573306131 | d24a77d1-aec3-11ea-9399-0242c0a84484 |
+-----------+----------------+------+-----------+--------------------------------------+
2 rows in set (0.00 sec)

https://cdn.jsdelivr.net/gh/lhrbest/pic/img/20210416111806.png

三、配置ProxySQL环境

3.1 申请ProxySQL主机并安装ProxySQL

docker rm -f MHA-LHR-ProxySQL-ip136
docker run -d --name MHA-LHR-ProxySQL-ip136 -h MHA-LHR-ProxySQL-ip136 \
  -v /sys/fs/cgroup:/sys/fs/cgroup \
  --network mhalhr --ip 192.168.68.136 \
  -p 26032:6032 -p 26033:6033 -p 26080:6080 \
  --privileged=true lhrbest/lhrcentos76:8.0 \
  /usr/sbin/init

docker network connect bridge MHA-LHR-ProxySQL-ip136
docker restart MHA-LHR-ProxySQL-ip136

docker cp proxysql2-2.0.15-1.1.el7.x86_64.rpm MHA-LHR-ProxySQL-ip136:/
docker exec -it MHA-LHR-ProxySQL-ip136 bash
rpm -ivh proxysql2-2.0.15-1.1.el7.x86_64.rpm
systemctl start proxysql
systemctl status proxysql

3.2 添加远程登录用户

-- 添加远程登录用户
mysql -uadmin -padmin -h127.0.0.1 -P6032
select @@admin-admin_credentials;
set admin-admin_credentials='admin:admin;root:lhr';
select @@admin-admin_credentials;
load admin variables to runtime;
save admin variables to disk;

-- 远程登录
mysql -uroot -plhr -h192.168.66.35 -P26032

执行过程：

-- ProxySQL本地登录
[root@MHA-LHR-ProxySQL-ip136 /]# mysql -uadmin -padmin -h127.0.0.1 -P6032
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 162
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

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

mysql> select @@admin-admin_credentials;
+---------------------------+
| @@admin-admin_credentials |
+---------------------------+
| admin:admin;lhr:lhr       |
+---------------------------+
1 row in set (0.05 sec)

mysql> set admin-admin_credentials='admin:admin;root:lhr';
Query OK, 1 row affected (0.00 sec)

mysql> select @@admin-admin_credentials;
+---------------------------+
| @@admin-admin_credentials |
+---------------------------+
| admin:admin;root:lhr      |
+---------------------------+
1 row in set (0.00 sec)

mysql> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

mysql> save admin variables to disk;
Query OK, 35 rows affected (0.13 sec)

mysql> 

-- 远程登录
C:\Users\lhrxxt>mysql -uroot -plhr -h192.168.66.35 -P26032
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1045 (28000): ProxySQL Error: Access denied for user 'root'@'172.17.0.1' (using password: YES)

C:\Users\lhrxxt>mysql -uroot -plhr -h192.168.66.35 -P26032
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 163
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

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

MySQL [(none)]> show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | disk          | /var/lib/proxysql/proxysql.db       |
| 3   | stats         |                                     |
| 4   | monitor       |                                     |
| 5   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
5 rows in set (0.05 sec)

3.3 开启ProxySQL的web监控功能

-- 开启web监控功能
SET admin-web_enabled='true';
LOAD ADMIN VARIABLES TO RUNTIME;
SAVE ADMIN VARIABLES TO DISK;
select * from global_variables where variable_name LIKE 'admin-web_enabled';
select @@admin-web_enabled;

lsof -i:6080

-- 浏览器访问
https://192.168.66.35:26080
用户名和密码：stats:stats

https://cdn.jsdelivr.net/gh/lhrbest/pic/img/20210416111815.png

3.4 配置被监控的数据库

3.4.1 向ProxySQL插入被监控数据库

-- 1、向ProxySQL插入被监控数据库
select * from mysql_servers;
insert into main.mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.68.131',3306);
insert into main.mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.68.132',3306);
insert into main.mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.68.133',3306);
load mysql servers to runtime;
save mysql servers to disk;
select * from mysql_servers;
MySQL [(none)]> select * from mysql_servers;
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.68.131 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 10           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 10           | 192.168.68.133 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
3 rows in set (0.07 sec)

3.4.2 在所有被监控MySQL服务器上创建监控帐户

-- 2、在所有被监控MySQL服务器上创建帐户，注意：新版本中，这里的密码必须为monitor，可参考配置文件/etc/proxysql.cnf
mysql -uroot -plhr -h192.168.66.35 -P33131
create user 'monitor'@'%' IDENTIFIED BY 'monitor';
GRANT all privileges ON *.* TO 'monitor'@'%' with grant option;
select user,host from mysql.user;

mysql> select user,host from mysql.user;
+---------------+--------------+
| user          | host         |
+---------------+--------------+
| mha           | %            |
| monitor       | %            |
| repl          | %            |
| root          | %            |
| mysql.session | localhost    |
| mysql.sys     | localhost    |
| root          | localhost    |
+---------------+--------------+
7 rows in set (0.00 sec)

3.4.3 在所有被监控MySQL服务器上创建对外访问账户

-- 3、 在所有被监控MySQL服务器上创建对外访问账户：
create user 'wr'@'%' IDENTIFIED BY 'lhr';
GRANT all privileges ON *.* TO 'wr'@'%' with grant option; 

-- 配置到ProxySQL中
insert into mysql_users(username,password,default_hostgroup) values('wr','lhr',10);
update mysql_users set transaction_persistent=1 where username='wr';
load mysql users to runtime;
save mysql users to disk;
select * from mysql_users;

MySQL [(none)]> select * from mysql_users;
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+---------+
| username | password | active | use_ssl | default_hostgroup | default_schema | schema_locked | transaction_persistent | fast_forward | backend | frontend | max_connections | comment |
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+---------+
| wr       | lhr      | 1      | 0       | 10                | NULL           | 0             | 1                      | 0            | 1       | 1        | 10000           |         |
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+---------+
1 row in set (0.05 sec)

3.4.4 配置监控

-- 4、在ProxySQL端执行下列SQL语句：
set mysql-monitor_username='monitor';
set mysql-monitor_password='monitor';
load mysql servers to runtime;
save mysql servers to disk;
select * from global_variables where variable_name in('mysql-monitor_username','mysql-monitor_password');
+------------------------+----------------+
| variable_name          | variable_value |
+------------------------+----------------+
| mysql-monitor_password | monitor        |
| mysql-monitor_username | monitor        |
+------------------------+----------------+
2 rows in set (0.05 sec)
-- 检查连接到MySQL的日志
select * from monitor.mysql_server_ping_log order by time_start_us desc limit 6;
select * from monitor.mysql_server_connect_log order by time_start_us desc limit 6;
MySQL [(none)]> select * from monitor.mysql_server_ping_log order by time_start_us desc limit 6;
+----------------+------+------------------+----------------------+------------+
| hostname       | port | time_start_us    | ping_success_time_us | ping_error |
+----------------+------+------------------+----------------------+------------+
| 192.168.68.132 | 3306 | 1614050308827202 | 252                  | NULL       |
| 192.168.68.133 | 3306 | 1614050308716530 | 370                  | NULL       |
| 192.168.68.131 | 3306 | 1614050308605853 | 542                  | NULL       |
| 192.168.68.131 | 3306 | 1614050298778908 | 334                  | NULL       |
| 192.168.68.133 | 3306 | 1614050298690947 | 297                  | NULL       |
| 192.168.68.132 | 3306 | 1614050298605725 | 344                  | NULL       |
+----------------+------+------------------+----------------------+------------+
6 rows in set (0.06 sec)

MySQL [(none)]> select * from monitor.mysql_server_connect_log order by time_start_us desc limit 6;
+----------------+------+------------------+-------------------------+---------------+
| hostname       | port | time_start_us    | connect_success_time_us | connect_error |
+----------------+------+------------------+-------------------------+---------------+
| 192.168.68.131 | 3306 | 1614050285481316 | 1173                    | NULL          |
| 192.168.68.133 | 3306 | 1614050284894846 | 1008                    | NULL          |
| 192.168.68.132 | 3306 | 1614050284309124 | 970                     | NULL          |
| 192.168.68.131 | 3306 | 1614050225194575 | 1108                    | NULL          |
| 192.168.68.133 | 3306 | 1614050224751771 | 987                     | NULL          |
| 192.168.68.132 | 3306 | 1614050224309026 | 1294                    | NULL          |
+----------------+------+------------------+-------------------------+---------------+
6 rows in set (0.05 sec)

四、故障切换

在Manager节点检查SSH、复制及MHA的状态。

docker exec -it MHA-LHR-Monitor-ip134 bash
masterha_check_ssh --conf=/etc/mha/mha.cnf
masterha_check_repl --conf=/etc/mha/mha.cnf
masterha_check_status --conf=/etc/mha/mha.cnf

-- 启动MHA监控进程
nohup masterha_manager --conf=/etc/mha/mha.cnf  --ignore_last_failover < /dev/null > /usr/local/mha/manager_start.log 2>&1 &

--关闭MHA监控进程
masterha_stop --conf=/etc/mha/mha.cnf
[root@MHA-LHR-Monitor-ip134 /]# masterha_check_status --conf=/etc/mha/mha.cnf
mha (pid:3738) is running(0:PING_OK), master:192.168.68.131

接下来，宕掉主库，继续观察ProxySQL的情况：

 -- 宕掉主库
 docker stop MHA-LHR-Master1-ip131

MHA自动执行了故障转移，主库切换为132，并发送告警邮件：

https://cdn.jsdelivr.net/gh/lhrbest/pic/img/20210416111828.png

此时，来查看ProxySQL的情况：

MySQL [(none)]> select * from mysql_servers;
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.131 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.133 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
4 rows in set (0.05 sec)

MySQL [(none)]> select * from runtime_mysql_servers;
+--------------+----------------+------+-----------+---------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | gtid_port | status  | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+-----------+---------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.68.132 | 3306 | 0         | ONLINE  | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.131 | 3306 | 0         | SHUNNED | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.133 | 3306 | 0         | ONLINE  | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.132 | 3306 | 0         | ONLINE  | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
+--------------+----------------+------+-----------+---------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
4 rows in set (1.26 sec)

可以发现131已经变成SHUNNED状态，ProxySQL会避开这个主机。

此时再做压测等操作，所有负载会被分配到132和133上，此处不再测试。

接下来启动131，并以从库的身份加入原主从环境：

-- 启动131
docker start MHA-LHR-Master1-ip131

-- 在134的日志文件中找到恢复的语句
grep "All other slaves should start replication from here" /usr/local/mha/manager_running.log

-- 在131上执行恢复
mysql -uroot -plhr -h192.168.68.131 -P3306
CHANGE MASTER TO MASTER_HOST='192.168.68.132', 
MASTER_PORT=3306, 
MASTER_AUTO_POSITION=1,
MASTER_USER='repl',
MASTER_PASSWORD='lhr';

start slave;
show slave status \G

-- 设置只读
set global read_only=1;

查询ProxySQL：

MySQL [(none)]> select * from mysql_servers;
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.131 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.133 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
4 rows in set (0.06 sec)

可以看到131为只读。若想让132只写，则可以删除相关记录：

MySQL [(none)]> delete from mysql_servers where hostgroup_id=20 and  hostname='192.168.68.132';
Query OK, 1 row affected (0.06 sec)

MySQL [(none)]> load mysql servers to runtime;
Query OK, 0 rows affected (0.68 sec)

MySQL [(none)]> save mysql servers to disk;
Query OK, 0 rows affected (0.10 sec)

MySQL [(none)]> select * from mysql_servers;
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.131 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.133 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
3 rows in set (0.05 sec)

MySQL [(none)]> select * from runtime_mysql_servers;
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | gtid_port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.68.132 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.133 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
| 20           | 192.168.68.131 | 3306 | 0         | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              |         |
+--------------+----------------+------+-----------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
3 rows in set (0.94 sec)

可以看到132为主库，131和133为从库。Orchestrator界面：

https://cdn.jsdelivr.net/gh/lhrbest/pic/img/20210416111835.png

 

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