Openstack的mysql数据多主galera的错误

登录openstack的在dashboard,提示说权限验证错误，有2种情况： 1. 密码被人改了。 2. 系统发生了问题。

密码确认没人改，所以查看/var/log/keystone-all.log日志，发现一堆错误：

File "/usr/lib/python2.6/site-packages/keystone/assignment/core.py", line 262, in get_domain
    return self.driver.get_domain(domain_id)
  File "/usr/lib/python2.6/site-packages/keystone/assignment/backends/sql.py", line 526, in get_domain
    return self._get_domain(session, domain_id).to_dict()
  File "/usr/lib/python2.6/site-packages/keystone/assignment/backends/sql.py", line 519, in _get_domain
    ref = session.query(Domain).get(domain_id)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 775, in get
    return self._load_on_ident(key)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2512, in _load_on_ident
    return q.one()
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2184, in one
    ret = list(self)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2227, in __iter__
    return self._execute_and_instances(context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2240, in _execute_and_instances
    close_with_result=True)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2231, in _connection_from_session
    **kw)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/session.py", line 777, in connection
    close_with_result=close_with_result)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/session.py", line 783, in _connection_for_bind
    return engine.contextual_connect(**kwargs)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 2489, in contextual_connect
    self.pool.connect(),
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/pool.py", line 236, in connect
    return _ConnectionFairy(self).checkout()
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/pool.py", line 474, in checkout
    self)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/event.py", line 377, in __call__
    fn(*args, **kw)
  File "/usr/lib/python2.6/site-packages/keystone/common/sql/core.py", line 204, in mysql_on_checkout
    dbapi_conn.cursor().execute('select 1')
  File "/usr/lib64/python2.6/site-packages/MySQLdb/cursors.py", line 205, in execute
    self.errorhandler(self, exc, value)
  File "/usr/lib64/python2.6/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
    raise errorclass, errorvalue
OperationalError: (1047, 'Unknown command')

这里可以看出，是mysqldb引擎连接mysql进行数据操作mysql返回的错误，所以，基本判断是mysql出问题了，登录mysql,查询admin的密码，发现连mysql的use命令都无法使用。所以引出了mysql的galera的问题。

mysql的galera是一种多主的mysql的HA方案，由单独开发一段程序在mysql底层实现数据的复制，而在各个服务器操作mysql上基本和单机没有区别。 但是在线上没有做任何修改，一直运行的过程中，发生了一个错误：

[root@node-10 conf.d]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 30631
Server version: 5.5.28
 
Copyright (c) 2000, 2012, 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> use keystone;
ERROR 1047 (08S01): Unknown command

我们应该知道mysql的use命令肯定是存在的。如果我们真实输入一个不存在的命令，提示也应该是这样的：

Copyright (c) 2000, 2012, 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> test
    -> ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'test' at line 1

这里先初步解决，让服务器运行起来，重启服务即可

service mysql restart

注意，这里/etc/init.d/mysql这个文件是使用了galera的定制化的脚本，理论上是将集群中所有的mysql服务重启，如果失败，可以手动kill -9即可。

然后再登录openstack的HA环境，就可以成功了。