种种迹象显示 MySQL 已经启动，但是各种需要数据库的程序都无法连接？

如题。 首先是基本系统情况：

• OS:Ubuntu 14.04 x64 LTS
• 数据库： Percona Server 5.7
• PHP ： PHP 7.0.9
• 应用： WordPress 、 phpMyAdmin

我做的一些排查工作：

 blog service mysql status * Percona Server 5.7.13-6 is running blog netstat -ap | grep mysql tcp 0 0 localhost:mysql *:* LISTEN 20978/mysqld blog mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. 

Percona日志显示：

2016-08-07T11:49:26.189089Z 0 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.7.13-6' socket: '/var/run/mysqld/mysqld.sock' port: 3306 Percona Server (GPL), Release '6', Revision 'e3d58bb' 

但是无论 WordPress 还是 phpmyadmin ，均不能连接 percona 。数据库主机尝试过设置 localhost 和 127.0.0.1 ，均无果。

下面是 percona 配置文件，完全官方，没有任何更改（/etc/mysql/my.cnf ）：

# # The MySQL database server configuration file. # # You can copy this to one of: # - "/etc/mysql/my.cnf" to set global options, # - "~/.my.cnf" to set user-specific options. # # One can use all long options that the program supports. # Run program with --help to get a list of available options and with # --print-defaults to see which it would actually understand and use. # # For explanations see # http://dev.mysql.com/doc/mysql/en/server-system-variables.html # This will be passed to all mysql clients # It has been reported that passwords should be enclosed with ticks/quotes # escpecially if they contain "#" chars... # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [client] port = 3306 socket = /var/run/mysqld/mysqld.sock # Here is entries for some specific programs # The following values assume you have at least 32M ram # This was formally known as [safe_mysqld]. Both versions are currently parsed. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # # * Basic Settings # user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp lc-messages-dir = /usr/share/mysql skip-external-locking # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. bind-address = 127.0.0.1 # # * Fine Tuning # #key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 # This replaces the startup script and checks MyISAM tables if needed # the first time they are touched #myisam-recover = BACKUP #max_cOnnections= 100 #table_cache = 64 #thread_cOncurrency= 10 # # * Query Cache Configuration # query_cache_limit = 1M query_cache_size = 16M # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. # As of 5.1 you can enable the log at runtime! #general_log_file = /var/log/mysql/mysql.log #general_log = 1 # # Error log - should be very few entries. # log_error = /var/log/mysql/error.log # # Here you can see queries with especially long duration #log_slow_queries = /var/log/mysql/mysql-slow.log #long_query_time = 2 #log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. # note: if you are setting up a replication slave, see README.Debian about # other settings you may need to change. #server-id = 1 #log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = include_database_name # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] #key_buffer = 16M # # * IMPORTANT: Additional settings that can override those from this file! # The files must end with '.cnf', otherwise they'll be ignored. # !includedir /etc/mysql/conf.d/ 

另外， PHP 和 MySQL 以及 nginx 的错误日志都有排查过，没有发现任何报错……

求教各位大神，感谢！