作者：杨涛涛

本文介绍用 MySQL Shell 搭建 MGR 的详细过程。
1、使用前，关掉防火墙，包括 selinux，firewalld，或者 MySQL 企业版的firewall（如果用了企业版的话）
2、两台机器：（4 台 MySQL 实例）

192.168.2.219 centos-ytt57-1 3311/3312
192.168.2.229 centos-ytt57-2 3311/3312

3、安装 MySQL（两台都装）, MySQL Shell（任意一台）, mysqlrouter(任意一台，官方建议和应用程序装在一个服务器上)

yum install mysql-community-server mysql-shell mysql-router-community

4、搭建 InnoDB-Cluster（两台都装）

1. 配置文件如下：

shell>vi /etc/my.cnf
master-info-repository=table
relay-log-info-repository=table
gtid_mode=ON
enforce_gtid_consistency=ON
binlog_checksum=NONE
log_slave_updates=ON
binlog_format=ROW
transaction_write_set_extraction=XXHASH64

1. 系统 HOSTS 配置（两台都配）

shell>vi /etc/hosts

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.2.219 centos-ytt57-2
192.168.2.229 centos-ytt57-3

用 MySQL coalesce 函数确认下 report-host 是否设置正确

(root@localhost) : [(none)] >SELECT coalesce(@@report_host, @@hostname) as r;
+----------------+
| r |
+----------------+
| centos-ytt57-1 |
+----------------+
1 row in set (0.00 sec)

1. 创建管理员用户搭建 GROUP REPLICATION （四个节点都要）

create user root identified by 'Root@123';
grant all on *.* to root with grant option;
flush privileges;

1. MySQLsh 连接其中一台节点：

[root@centos-ytt57-1 mysql]# mysqlsh root@localhost:3321

1. 检查配置正确性：（如果这里不显示 OK，把对应的参数加到配置文件重启 MySQL 再次检查）

dba.checkInstanceConfiguration(“root@centos-ytt57-2:3311”);
dba.checkInstanceConfiguration(“root@centos-ytt57-2:3312”);
dba.checkInstanceConfiguration(“root@centos-ytt57-3:3311”);
dba.checkInstanceConfiguration(“root@centos-ytt57-3:3312”);
mysqlsh 执行检测

[root@centos-ytt57-1 mysql]# mysqlsh --log-level=8 root@localhost:3311

MySQL localhost:3311 ssl JS > dba.checkInstanceConfiguration("root@centos-ytt57-2:3311")
{
"status": "ok"
}

1. 创建集群，节点 1 上创建。（结果显示 Cluster successfully created 表示成功）

MySQL localhost:3311 ssl JS > var cluster = dba.createCluster('ytt_mgr');

Cluster successfully created. Use Cluster.addInstance() to add MySQL instances.
At least 3 instances are needed for the cluster to be able to withstand up to
one server failure.

1. 添加节点 2，3，4（全部显示 OK，表示添加成功）

MySQL  localhost:3311 ssl  JS >  cluster.addInstance('root@centos-ytt57-2:3312');
MySQL  localhost:3311 ssl  JS >  cluster.addInstance('root@centos-ytt57-3:3311');
MySQL  localhost:3311 ssl  JS >  cluster.addInstance('root@centos-ytt57-3:3312');

1. 查看拓扑图：（describe 简单信息，status 详细描述）

MySQL localhost:3311 ssl JS > cluster.describe()
{
"clusterName": "ytt_mgr",
"defaultReplicaSet": {
"name": "default",
"topology": [
{
"address": "centos-ytt57-2:3311",
"label": "centos-ytt57-2:3311",
"role": "HA",
"version": "8.0.17"
},
{
"address": "centos-ytt57-2:3312",
"label": "centos-ytt57-2:3312",
"role": "HA",
"version": "8.0.17"
},
{
"address": "centos-ytt57-3:3311",
"label": "centos-ytt57-3:3311",
"role": "HA",
"version": "8.0.17"
},
{
"address": "centos-ytt57-3:3312",
"label": "centos-ytt57-3:3312",
"role": "HA",
"version": "8.0.17"
}
],
"topologyMode": "Single-Primary"
}
}

MySQL localhost:3311 ssl JS > cluster.status()

"clusterName": "ytt_mgr",
"defaultReplicaSet": {
"name": "default",
"primary": "centos-ytt57-2:3311",
"ssl": "REQUIRED",
"status": "OK",
"statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",
"topology": {
"centos-ytt57-2:3311": {
"address": "centos-ytt57-2:3311",
"mode": "R/W",
"readReplicas": {},
"role": "HA",
"status": "ONLINE",
"version": "8.0.17"
},
"centos-ytt57-2:3312": {
"address": "centos-ytt57-2:3312",
"mode": "R/O",
"readReplicas": {},
"role": "HA",
"status": "ONLINE",
"version": "8.0.17"
},
"centos-ytt57-3:3311": {
"address": "centos-ytt57-3:3311",
"mode": "R/O",
"readReplicas": {},
"role": "HA",
"status": "ONLINE",
"version": "8.0.17"
},
"centos-ytt57-3:3312": {
"address": "centos-ytt57-3:3312",
"mode": "R/O",
"readReplicas": {},
"role": "HA",
"status": "ONLINE",
"version": "8.0.17"
}
},
"topologyMode": "Single-Primary"
},
"groupInformationSourceMember": "centos-ytt57-2:3311"

1. 简单测试下数据是否同步

(root@localhost) : [(none)] >create database ytt;
Query OK, 1 row affected (0.03 sec)

(root@localhost) : [(none)] >use ytt;
Database changed
(root@localhost) : [ytt] >create table p1(id int primary key, log_time datetime);
Query OK, 0 rows affected (0.08 sec)

(root@localhost) : [ytt] >insert into p1 values (1,now());
Query OK, 1 row affected (0.04 sec)

(root@localhost) : [ytt] >show master status;
+---------------+----------+--------------+------------------+-------------------------------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+---------------+----------+--------------+------------------+-------------------------------------------+
| mysql0.000001 | 25496 | | | 6c7bb9db-b759-11e9-a9c0-0800276cf0fc:1-41 |
+---------------+----------+--------------+------------------+-------------------------------------------+
1 row in set (0.00 sec)

查看其他三个节点

(root@localhost) : [ytt] >show tables;
+---------------+
| Tables_in_ytt |
+---------------+
| p1 |
+---------------+
1 row in set (0.00 sec)

(root@localhost) : [ytt] >select * from p1;
+----+---------------------+
| id | log_time |
+----+---------------------+
| 1 | 2019-08-05 16:44:20 |
+----+---------------------+
1 row in set (0.00 sec)

停掉主节点：

[root@centos-ytt57-2 mysql0]# systemctl stop mysqld@0

现在查看，主节点已经变为本机 3312节点

"centos-ytt57-2:3312": {
"address": "centos-ytt57-2:3312",
"mode": "R/W",
"readReplicas": {},
"role": "HA",
"status": "ONLINE"
}

1. 报错处理

错误日志里显示

2019-08-05T09:01:35.125591Z 0 [ERROR] Plugin group_replication reported: 'The group name option is mandatory'
2019-08-05T09:01:35.125622Z 0 [ERROR] Plugin group_replication reported: 'Unable to start Group Replication on boot'

同时用 cluster.rescan() 扫描，发现

The instance 'centos-ytt57-2:3311' is no longer part of the ReplicaSet.

重新加入此节点到集群：

cluster.rejoinInstance('centos-ytt57-2:3311')

再次执行cluster.status()查看集群状态：”status”: “OK”,

1. 移除和加入

cluster.removeInstance("centos-ytt57-3:3312");
The instance 'centos-ytt57-3:3312' was successfully removed from the cluster.
cluster.addInstance("centos-ytt57-3:3312");
The instance 'centos-ytt57-3:3312' was successfully added to the cluster.

1. 用 mysqlrouter 生成连接 MGR 相关信息。

涉及到两个用户：
–user=mysqlrouter 是使用mysqlrouter的系统用户
自动创建的MySQL 用户是用来与MGR通信的用户。如果想查看这个用户的用户名以及密码，就加上
–force-password-validation，不过一般也没有必要查看。

[root@centos-ytt57-2 ytt]# mysqlrouter --bootstrap root@centos-ytt57-2:3311 --user=mysqlrouter --force-password-validation --report-host centos-ytt57-2
Please enter MySQL password for root:

# Reconfiguring system MySQL Router instance...

- Checking for old Router accounts
- Found old Router accounts, removing
- Creating mysql account mysql_router1_rdr89tx20r0a@'%' for cluster management
- Storing account in keyring
- Adjusting permissions of generated files
- Creating configuration /etc/mysqlrouter/mysqlrouter.conf

# MySQL Router configured for the InnoDB cluster 'ytt_mgr'

After this MySQL Router has been started with the generated configuration

$ /etc/init.d/mysqlrouter restart
or
$ systemctl start mysqlrouter
or
$ mysqlrouter -c /etc/mysqlrouter/mysqlrouter.conf

the cluster 'ytt_mgr' can be reached by connecting to:

## MySQL Classic protocol

- Read/Write Connections: centos-ytt57-2:6446
- Read/Only Connections: centos-ytt57-2:6447

## MySQL X protocol

- Read/Write Connections: centos-ytt57-2:64460
- Read/Only Connections: centos-ytt57-2:64470

1. 启动 mysqlrouter，生效对应服务。

[root@centos-ytt57-2 mysqlrouter]# systemctl start mysqlrouter

1. 使用 ROUTER 连接 MySQL

创建一个普通用户使用 ROUTER (四个节点都建立，具体权限看个人)

[root@centos-ytt57-2 mysqlrouter]# /home/ytt/enter_mysql 80
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 1779
Server version: 8.0.17 MySQL Community Server - GPL

Copyright (c) 2000, 2019, 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.

(root@centos-ytt57-2) : [(none)] >create user ytt_mysqlrouter;
Query OK, 0 rows affected (0.12 sec)

(root@centos-ytt57-2) : [(none)] >alter user ytt_mysqlrouter identified by 'mysql_router';
Query OK, 0 rows affected (0.09 sec)

(root@centos-ytt57-2) : [(none)] >grant all on ytt.* to ytt_mysqlrouter;
Query OK, 0 rows affected (0.05 sec)

(root@centos-ytt57-2) : [(none)] >flush privileges;
Query OK, 0 rows affected (0.07 sec)

14.1 写入端口连接：

[root@centos-ytt57-2 mysqlrouter]# mysql -uytt_mysqlrouter -pmysql_router -hcentos-ytt57-2 -P6446
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 2030
Server version: 8.0.17 MySQL Community Server - GPL

Copyright (c) 2000, 2019, 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.

(ytt_mysqlrouter@centos-ytt57-2) : [(none)] >use ytt
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >insert into p1 values (200,now());
Query OK, 1 row affected (0.04 sec)

(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >select * from p1;
+-----+---------------------+
| id | log_time |
+-----+---------------------+
| 1 | 2019-08-05 23:15:38 |
| 2 | 2019-08-05 23:15:42 |
| 100 | 2019-08-05 23:52:58 |
| 200 | 2019-08-05 23:56:23 |
+-----+---------------------+
4 rows in set (0.00 sec)

(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >\q
Bye
[root@centos-ytt57-2 mysqlrouter]#

14.2 读取端口连接：（默认循环选择读服务节点）

[root@centos-ytt57-2 mysqlrouter]# mysql -uytt_mysqlrouter -pmysql_router -hcentos-ytt57-2 -P6447
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 472
Server version: 8.0.17 MySQL Community Server - GPL

Copyright (c) 2000, 2019, 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.

(ytt_mysqlrouter@centos-ytt57-2) : [(none)] >use ytt
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >insert into p1 values (300,now());
ERROR 1290 (HY000): The MySQL server is running with the --read-only option so it cannot execute this statement
(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >select * from p1;
+-----+---------------------+
| id | log_time |
+-----+---------------------+
| 1 | 2019-08-05 23:15:38 |
| 2 | 2019-08-05 23:15:42 |
| 100 | 2019-08-05 23:52:58 |
| 200 | 2019-08-05 23:56:23 |
+-----+---------------------+
4 rows in set (0.00 sec)
## (ytt_mysqlrouter@centos-ytt57-2) : [ytt] >\s

mysql Ver 8.0.17 for Linux on x86_64 (MySQL Community Server - GPL)

Connection id: 472
Current database: ytt
Current user: ytt_mysqlrouter@centos-ytt57-2
SSL: Cipher in use is DHE-RSA-AES128-GCM-SHA256
Current pager: stdout
Using outfile: ''
Using delimiter: ;
Server version: 8.0.17 MySQL Community Server - GPL
Protocol version: 10
Connection: centos-ytt57-2 via TCP/IP
Server characterset: utf8mb4
Db characterset: utf8mb4
Client characterset: utf8mb4
Conn. characterset: utf8mb4
TCP port: 6447
Uptime: 45 min 10 sec

## Threads: 5 Questions: 188 Slow queries: 0 Opens: 257 Flush tables: 3 Open tables: 161 Queries per second avg: 0.069



(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >select @@server_id;
+-------------+
| @@server_id |
+-------------+
| 2 |
+-------------+
1 row in set (0.01 sec)

(ytt_mysqlrouter@centos-ytt57-2) : [ytt] >\q
Bye

1. 机器全挂了，重启 MGR

MySQL localhost:3311 ssl JS > dba.rebootClusterFromCompleteOutage()
Reconfiguring the default cluster from complete outage...

The instance 'centos-ytt57-2:3312' was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y

The instance 'centos-ytt57-3:3311' was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y

The instance 'centos-ytt57-3:3312' was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y

The safest and most convenient way to provision a new instance is through
automatic clone provisioning, which will completely overwrite the state of
'localhost:3311' with a physical snapshot from an existing cluster member. To
use this method by default, set the 'recoveryMethod' option to 'clone'.

The incremental distributed state recovery may be safely used if you are sure
all updates ever executed in the cluster were done with GTIDs enabled, there
are no purged transactions and the new instance contains the same GTID set as
the cluster or a subset of it. To use this method by default, set the
'recoveryMethod' option to 'incremental'.

Incremental distributed state recovery was selected because it seems to be safely usable.

^C
The cluster was successfully rebooted.
Script execution interrupted by user.
MySQL  localhost:3311 ssl  JS > var cluster = dba.getCluster('ytt_mgr');
MySQL  localhost:3311 ssl  JS > cluste.status();
ReferenceError: cluste is not defined
MySQL  localhost:3311 ssl  JS > cluster.status();
{
   "clusterName": "ytt_mgr",
   "defaultReplicaSet": {
       "name": "default",
       "primary": "centos-ytt57-2:3311",
       "ssl": "REQUIRED",
       "status": "OK",
       "statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",
       "topology": {
           "centos-ytt57-2:3311": {
               "address": "centos-ytt57-2:3311",
               "mode": "R/W",
               "readReplicas": {},
               "role": "HA",
               "status": "ONLINE",
               "version": "8.0.17"
           },
           "centos-ytt57-2:3312": {
               "address": "centos-ytt57-2:3312",
               "mode": "R/O",
               "readReplicas": {},
               "role": "HA",
               "status": "ONLINE",
               "version": "8.0.17"
           },
           "centos-ytt57-3:3311": {
               "address": "centos-ytt57-3:3311",
               "mode": "R/O",
               "readReplicas": {},
               "role": "HA",
               "status": "ONLINE",
               "version": "8.0.17"
           },
           "centos-ytt57-3:3312": {
               "address": "centos-ytt57-3:3312",
               "mode": "R/O",
               "readReplicas": {},
               "role": "HA",
               "status": "ONLINE",
               "version": "8.0.17"
           }
       },
       "topologyMode": "Single-Primary"
   },
   "groupInformationSourceMember": "centos-ytt57-2:3311"
}