MySQL 8.0新特性之ROLE的學習筆記

Role功能可以說是一個期待已有的功能，這從它的Worklog號(WL#988)就可以看出來，這是個相當早並且呼聲很高的需求了。

所謂Role，可以認為是一個許可權的集合，這個集合有一個統一的名字，就是Role名，你可以為多個賬戶賦予統一的某個Role的許可權，而許可權的修改可以直接通過修改Role來實現，而無需每個賬戶逐一GRANT許可權，大大方便了營運和管理。

Role可以被建立，修改和刪除，並作用到其所屬於的賬戶上。

舉個簡單的例子。建立如下測試表

mysql> create database testdb;
Query OK, 1 row affected (0.00 sec)

mysql> use testdb; create table t1 (a int, b int, primary key(a));
Database changed
Query OK, 0 rows affected (0.00 sec)

mysql> insert into t1 values (1,2);
Query OK, 1 row affected (0.00 sec)

建立Role，擁有t1表的查詢許可權:

mysql> create role priv_t1;
Query OK, 0 rows affected (0.00 sec)

mysql> grant select on testdb.t1 to 'priv_t1';
Query OK, 0 rows affected (0.00 sec)

建立一個賬戶，並將role的許可權賦給它

mysql> create user 'rw_user1'@'%' identified by 'xxx';
Query OK, 0 rows affected (0.00 sec)

mysql> grant 'priv_t1' to 'rw_user1'@'%';
Query OK, 0 rows affected (0.00 sec)

以rw_user1登入

---- 查看許可權

mysql> show grants;
+---------------------------------------+
| Grants for rw_user1@%        |
+---------------------------------------+
| GRANT USAGE ON *.* TO `rw_user1`@`%`  |
| GRANT `priv_t1`@`%` TO `rw_user1`@`%` |
+---------------------------------------+
2 rows in set (0.00 sec)

## 需要加using "role名"才會展開許可權

mysql> show grants for 'rw_user1'@'%' using priv_t1;
+-------------------------------------------------+
| Grants for rw_user1@%                           |
+-------------------------------------------------+
| GRANT USAGE ON *.* TO `rw_user1`@`%`            |
| GRANT SELECT ON `testdb`.`t1` TO `rw_user1`@`%` |
| GRANT `priv_t1`@`%` TO `rw_user1`@`%`           |
+-------------------------------------------------+
3 rows in set (0.00 sec)

然而此時並不能直接獲得t1表的查詢許可權， 你需要手動進行選擇哪些role在賬戶串連上來時被啟用，如下:

mysql> select * from testdb.t1;
ERROR 1142 (42000): SELECT command denied to user 'rw_user1'@'localhost' for table 't1'

mysql> SET DEFAULT ROLE ALL TO 'rw_user1'@'%';
Query OK, 0 rows affected (0.00 sec)

--- 重新登入生效

mysql> select user();
+--------------------+
| user()             |
+--------------------+
| rw_user1@localhost |
+--------------------+
1 row in set (0.00 sec)

mysql> select * from testdb.t1;
+---+------+
| a | b    |
+---+------+
| 1 |    2 |
+---+------+
1 row in set (0.00 sec)

-- SET ROLE文法參閱官方文檔：
-- http://dev.mysql.com/doc/refman/8.0/en/set-default-role.html

修改role的許可權，會直接作用到對應的賬戶上:

--- 增加insert許可權
--- login as root

mysql> grant insert on testdb.t1 to 'priv_t1';
Query OK, 0 rows affected (0.00 sec)

--- login as rw_user1

mysql> insert into testdb.t1 values (2,3);
Query OK, 1 row affected (0.00 sec)

--- 刪除insert許可權
--- login as root

mysql> revoke insert on testdb.t1 from 'priv_t1';
Query OK, 0 rows affected (0.00 sec)

--- login as rw_user1

mysql> insert into testdb.t1 values (3,4);
ERROR 1142 (42000): INSERT command denied to user 'rw_user1'@'localhost' for table 't1'

增加了兩個系統資料表來維護Role資訊，一個是mysql.default_roles表，用於展示賬戶使用的預設role資訊，一個是role_edges，用於展示已建立的role資訊

mysql> select * from default_roles;
+------+----------+-------------------+-------------------+
| HOST | USER     | DEFAULT_ROLE_HOST | DEFAULT_ROLE_USER |
+------+----------+-------------------+-------------------+
| %    | rw_user1 | %                 | priv_t1           |
+------+----------+-------------------+-------------------+
1 row in set (0.00 sec)

 

mysql> select * from role_edges;
+-----------+-----------+---------+----------+-------------------+
| FROM_HOST | FROM_USER | TO_HOST | TO_USER  | WITH_ADMIN_OPTION |
+-----------+-----------+---------+----------+-------------------+
| %         | priv_t1   | %       | rw_user1 | N                 |
+-----------+-----------+---------+----------+-------------------+
1 row in set (0.00 sec)

新增函數用於顯示當前賬戶使用的role：

mysql> select current_role();
+----------------+
| current_role() |
+----------------+
| `priv_t1`@`%`  |
+----------------+
1 row in set (0.00 sec)