[已解决] 手动构建的GreatSQL MGR集群（含仲裁节点）如何用shell接管

1075 3 2023-10-26 15:04

如题，一个包含仲裁节点（ARBITRATOR）的GreatSQL MGR集群，一开始是采用手动方式构建，后来想用MySQL Shell接管，可以吗？

答：
是可以的，不过也有一定局限性，大致的做法/过程如下：
1. 确认当前MGR集群正常
```
greatsql> select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+---------------+-------------+--------------+-------------+----------------+----------------------------+
| CHANNEL_NAME             | MEMBER_ID                         | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION | MEMBER_COMMUNICATION_STACK |
+---------------------------+--------------------------------------+---------------+-------------+--------------+-------------+----------------+----------------------------+
| group_replication_applier | 04b57be0-73a0-11ee-a450-00155d064000 | 192.168.5.170 |       3307 | ONLINE    | SECONDARY | 8.0.32       | XCom                      |
| group_replication_applier | 0b157081-73a7-11ee-899b-00155d064000 | 192.168.5.170 |       3308 | ONLINE    | ARBITRATOR  | 8.0.32       | XCom                      |
| group_replication_applier | d4b877cf-16f0-11ee-9e98-00155d064000 | 192.168.5.170 |       3306 | ONLINE    | PRIMARY    | 8.0.32       | XCom                      |
+---------------------------+--------------------------------------+---------------+-------------+--------------+-------------+----------------+----------------------------+
3 rows in set (0.00 sec)
```

2. 连接primary节点，对MGR专属账户增加相应授权：
```
-- 查看原来的授权
greatsql> show grants for GreatSQL;
+--------------------------------------------------+
| Grants for GreatSQL@%                         |
+--------------------------------------------------+
| GRANT REPLICATION SLAVE ON *.* TO `GreatSQL`@`%` |
| GRANT BACKUP_ADMIN ON *.* TO `GreatSQL`@`%`    |
+--------------------------------------------------+

-- 上述结果不足以让Shell使用，需要增加授权
-- 参考其他用Shell接管的MGR集群专属账户授权，手动添加，最后达到如下结果

greatsql> show grants for GreatSQL;
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Grants for GreatSQL@%                                                                                                                                                                                                                                                       |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| GRANT SELECT, RELOAD, SHUTDOWN, PROCESS, FILE, EXECUTE, REPLICATION SLAVE, REPLICATION CLIENT, CREATE USER ON *.* TO `GreatSQL`@`%` WITH GRANT OPTION                                                                                                                      |
| GRANT BACKUP_ADMIN ON *.* TO `GreatSQL`@`%`                                                                                                                                                                                                                               |
| GRANT CLONE_ADMIN,CONNECTION_ADMIN,GROUP_REPLICATION_ADMIN,PERSIST_RO_VARIABLES_ADMIN,REPLICATION_APPLIER,REPLICATION_SLAVE_ADMIN,ROLE_ADMIN,SYSTEM_VARIABLES_ADMIN ON *.* TO `GreatSQL`@`%` WITH GRANT OPTION                                                             |
| GRANT INSERT, UPDATE, DELETE ON `mysql`.* TO `GreatSQL`@`%` WITH GRANT OPTION                                                                                                                                                                                              |
| GRANT INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER ON `mysql_innodb_cluster_metadata`.* TO `GreatSQL`@`%` WITH GRANT OPTION       |
| GRANT INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER ON `mysql_innodb_cluster_metadata_bkp`.* TO `GreatSQL`@`%` WITH GRANT OPTION    |
| GRANT INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER ON `mysql_innodb_cluster_metadata_previous`.* TO `GreatSQL`@`%` WITH GRANT OPTION |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

```
上述授权工作在primary节点执行完后，secondary节点会自动跟随。ARBITRATOR节点需要手动处理。

3. 对ARBITRATOR节点手动增加授权
修改ARBITRATOR节点的my.cnf，关闭ARBITRATOR角色（设置 `group_replication_arbitrator = 0`），并记得确保MGR不会自动启动（设置 `group_replication_start_on_boot = OFF`），然后重启该实例。

重启完成后，此时尚未启动MGR进程，因此ARBITRATOR节点会变成一个普通实例，可以对其进行读写操作。
```
-- 手动增加相应授权
greatsql> set sql_log_bin = 0;
-- 参考第2步，手动增加相应授权
greatsql> GRANT ....
```
确认授权完成后，即可关闭该实例，重新启用ARBITRATOR角色（设置 `group_replication_arbitrator = 1`），重启实例，但先不启动 MGR进程，后面再说。

4. 开始用MySQL Shell接管MGR
利用Shell接管现有MGR：
```
$ mysqlsh> c=dba.create_cluster("mgr",{"adoptFromGR": "true"})
```
参数 {"adoptFromGR": "true"} 的作用就是告诉Shell，接管现有MGR集群，而不是全新创建一个。

之后会很顺利地完成接管，此时只有primary和secondary两个节点：
```

shell> c=dba.create_cluster("mgr", {"adoptFromGR":"true"})
A new InnoDB cluster will be created based on the existing replication group on instance '127.0.0.1:3306'.

Creating InnoDB cluster 'mgr' on '192.168.5.170:3306'...

Adding Seed Instance...
Adding Instance '192.168.5.170:3307'...
Adding Instance '192.168.5.170:3306'...
Resetting distributed recovery credentials across the cluster...
NOTE: User 'mysql_innodb_cluster_3307'@'%' already existed at instance '192.168.5.170:3306'. It will be deleted and created again with a new password.
Cluster successfully created based on existing replication group.

shell> c.status()
{
"clusterName": "mgr",
"defaultReplicaSet": {
      "name": "default",
      "primary": "192.168.5.170:3306",
      "ssl": "DISABLED",
      "status": "OK_NO_TOLERANCE",
      "statusText": "Cluster is NOT tolerant to any failures.",
      "topology": {
         "192.168.5.170:3306": {
            "address": "192.168.5.170:3306",
            "memberRole": "PRIMARY",
            "mode": "R/W",
            "readReplicas": {},
            "replicationLag": null,
            "role": "HA",
            "status": "ONLINE",
            "version": "8.0.32"
         },
         "192.168.5.170:3307": {
            "address": "192.168.5.170:3307",
            "memberRole": "SECONDARY",
            "mode": "R/O",
            "readReplicas": {},
            "replicationLag": null,
            "role": "HA",
            "status": "ONLINE",
            "version": "8.0.32"
         }
      },
      "topologyMode": "Single-Primary"
},
"groupInformationSourceMember": "192.168.5.170:3306"
}

```

5. 连接ARBITRATOR节点，启动MGR进程
连接ARBITRATOR节点，并执行 `start group_replication` 启动MGR进程，此时能看到各节点状态工作正常：
```
greatsql> select * from performance_schema.replication_group_members;
+---------------------------+--------------------------------------+---------------+-------------+--------------+-------------+----------------+----------------------------+
| CHANNEL_NAME             | MEMBER_ID                         | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE | MEMBER_VERSION | MEMBER_COMMUNICATION_STACK |
+---------------------------+--------------------------------------+---------------+-------------+--------------+-------------+----------------+----------------------------+
| group_replication_applier | 04b57be0-73a0-11ee-a450-00155d064000 | 192.168.5.170 |       3307 | ONLINE    | SECONDARY | 8.0.32       | XCom                      |
| group_replication_applier | 0b157081-73a7-11ee-899b-00155d064000 | 192.168.5.170 |       3308 | ONLINE    | ARBITRATOR  | 8.0.32       | XCom                      |
| group_replication_applier | d4b877cf-16f0-11ee-9e98-00155d064000 | 192.168.5.170 |       3306 | ONLINE    | PRIMARY    | 8.0.32       | XCom                      |
+---------------------------+--------------------------------------+---------------+-------------+--------------+-------------+----------------+----------------------------+
3 rows in set (0.00 sec)
```

切换到MySQL Shell查看：
```
shell> c.status()

"clusterName": "mgr",
"defaultReplicaSet": {
      "name": "default",
      "primary": "192.168.5.170:3306",
      "ssl": "DISABLED",
      "status": "OK",
      "statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",
      "topology": {
         "192.168.5.170:3306": {
            "address": "192.168.5.170:3306",
            "memberRole": "PRIMARY",
            "mode": "R/W",
            "readReplicas": {},
            "replicationLag": null,
            "role": "HA",
            "status": "ONLINE",
            "version": "8.0.32"
         },
         "192.168.5.170:3307": {
            "address": "192.168.5.170:3307",
            "memberRole": "SECONDARY",
            "mode": "R/O",
            "readReplicas": {},
            "replicationLag": null,
            "role": "HA",
            "status": "ONLINE",
            "version": "8.0.32"
         },
         "192.168.5.170:3308": {
            "address": "192.168.5.170:3308",
            "instanceErrors": [
                  "WARNING: Instance is not managed by InnoDB cluster. Use cluster.rescan() to repair."
            ],
            "memberRole": "ARBITRATOR",
            "mode": "R/O",
            "readReplicas": {},
            "replicationLag": null,
            "role": "HA",
            "status": "ONLINE",
            "version": "8.0.32"
         }
      },
      "topologyMode": "Single-Primary"
},
"groupInformationSourceMember": "192.168.5.170:3306"
}
```

可以看到已经能看到所有节点，包括 ARBITRATOR 节点，但是因为该节点无法对其进行读写，所以实际上Shell接入时的一些初始化工作还是没完全执行，所以才有上面的提示：
```

            "instanceErrors": [
                  "WARNING: Instance is not managed by InnoDB cluster. Use cluster.rescan() to repair."
            ],

```
不过并不影响，因为该节点只需参与MGR投票即可，可以忽略这个错误。

不知道注意到了没有，在这个过程中，并不需要像添加常规secondary节点那样要CLONE全量数据。

提醒：后续如果要通过Shell对MGR做些操作，可能ARBITRATOR节点会提示不支持，此时只需临时把ARBITRATOR的MGR进程关闭，必要的操作执行完毕后再次启动MGR进程即可。

至此，就完成了Shell接管MGR集群的过程。

Enjoy GreatSQL ：）

MGR, GreatSQL

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