mysql 8.0 的用户认证方式 caching_sha2_password、mysql_native_password

新安装mysql 8.0，在用户登录时提示这样的错误

Failed to connect to MySQL server: Authentication plugin 'caching_sha2_password' cannot be loaded: /usr/lib64/xtrabackup/plugin/caching_sha2_password.so: cannot open shared object file: No such file or directory.

在网上搜了下，发现主要是因为mysql 8.0的默认认证方式有了调整，可以选择不同的plugin。

ALTER USER 'root'@'localhost' IDENTIFIED BY 'password' PASSWORD EXPIRE NEVER; 
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password'; 
FLUSH PRIVILEGES; 

修改默认认证方式

默认的认证方式是 caching_sha2_password

mysql> show global variables like '%default_auth%';
+-------------------------------+-----------------------+
| Variable_name                 | Value                 |
+-------------------------------+-----------------------+
| default_authentication_plugin | caching_sha2_password |
+-------------------------------+-----------------------+
1 row in set (0.00 sec)

修改

# vi /etc/my.cnf

[mysqld]
default_authentication_plugin = mysql_native_password

修改已有用户的认证方式

mysql> select user,host,authentication_string,plugin,account_locked from mysql.user;

mysql> alter user 'root'@'192.168.56.%' identified with mysql_native_password by 'MyNewPass@123' PASSWORD EXPIRE NEVER;
Query OK, 0 rows affected (0.39 sec)

直接修改

mysql> alter user 'root'@'192.168.56.%' identified with mysql_native_password by 'MyNewPass@123' PASSWORD EXPIRE NEVER;
Query OK, 0 rows affected (0.39 sec)

caching_sha2_password、mysql_native_password

下面的问题源自mysql 官方文档
Important
In MySQL 8.0, caching_sha2_password is the default authentication plugin rather than mysql_native_password. For information about the implications of this change for server operation and compatibility of the server with clients and connectors, see caching_sha2_password as the Preferred Authentication Plugin.

参考：
https://dev.mysql.com/doc/refman/8.0/en/caching-sha2-pluggable-authentication.html