问题描述：
openstack 控制台 novnc报错，Failed to connect to server
原因为：
mysql 最大连接数太小，连接不了
解决过程：
进入controller节点查看nova日志
x
# tail -f -n100 /var/log/nova/nova-novncproxy.log2020-08-28 12:45:11.751 434322 INFO nova.console.websocketproxy [req-9caa0c61-7e85-4d3b-98a5-539ac884cb21 - - - - -] handler exception: (pymysql.err.OperationalError) (1040, u'Too many connections') (Background on this error at: http://sqlalche.me/e/e3q8)从日志可以看出是mysql连接数的问题，于是到数据库里查看：
看当前连接数，发现最大连接数太小
MariaDB [(none)]> show variables like '%max_connections%'; +-----------------------+-------+| Variable_name | Value |+-----------------------+-------+| extra_max_connections | 1 || max_connections | 594 |+-----------------------+-------+2 rows in set (0.001 sec)查看当前最大连接数MariaDB [(none)]> show variables like ‘%max_connections%’;将最大连接数改多点：MariaDB [(none)]> set GLOBAL max_connections=1000;Query OK, 0 rows affected (0.000 sec)MariaDB [(none)]> show variables like '%max_connections%'; +-----------------------+-------+| Variable_name | Value |+-----------------------+-------+| extra_max_connections | 1 || max_connections | 1000 |+-----------------------+-------+2 rows in set (0.001 sec)再回到控制台界面，就可以正常使用了
可以