[mysql] 记测试环境mariadb启动失败

背景

需要配置VM的硬件信息，故重启了VM，结果开机后mariadb启动失败：

# systemctl restart mariadb
Authorization not available. Check if polkit service is running or see debug message for more @R_162_4045@ion.
Job for mariadb.service Failed because the control process exited with error code. See "systemctl status mariadb.service" and "journalctl -xe" for details.

分析

按提示查看服务status

执行systemctl status mariadb.service查看：

● mariadb.service - MariaDB database server
   Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2021-12-08 09:38:23 CST; 2min 23s ago
  Process: 14882 ExecStartPost=/usr/libexec/mariadb-wait-ready $MAINPID (code=exited, status=0/SUCCESS)
  Process: 14846 ExecStartPre=/usr/libexec/mariadb-prepare-db-dir %n (code=exited, status=0/SUCCESS)
 Main PID: 14881 (MysqLd_safe)
   CGroup: /system.slice/mariadb.service
           ├─14881 /bin/sh /usr/bin/MysqLd_safe --basedir=/usr
           └─15070 /usr/libexec/MysqLd --basedir=/usr --datadir=/var/lib/MysqL --plugin-dir=/usr/lib64/MysqL/plugin --log-error=/var/log/mariadb/mariadb.log --pid-file=/var/log/mariadb/mariadb.pid --sock...

Dec 08 09:38:21 vm systemd[1]: Starting MariaDB database server...
Dec 08 09:38:21 vm mariadb-prepare-db-dir[14846]: Failed to get D-Bus connection: Permission denied
Dec 08 09:38:21 vm mariadb-prepare-db-dir[14846]: Failed to get D-Bus connection: Permission denied
Dec 08 09:38:21 vm mariadb-prepare-db-dir[14846]: Database MariaDB is probably initialized in /var/lib/MysqL already, nothing is done.
Dec 08 09:38:21 vm mariadb-prepare-db-dir[14846]: If this is not the case, make sure the /var/lib/MysqL is empty before running mariadb-prepare-db-dir.
Dec 08 09:38:21 vm MysqLd_safe[14881]: 211208 09:38:21 MysqLd_safe Logging to '/var/log/mariadb/mariadb.log'.
Dec 08 09:38:21 vm MysqLd_safe[14881]: 211208 09:38:21 MysqLd_safe Starting MysqLd daemon with databases from /var/lib/MysqL
Dec 08 09:38:23 vm systemd[1]: Started MariaDB database server.

查看log文件

大致是因为某个权限问题，但上面看不出来，只能再查看log文件vi /var/log/mariadb/mariadb.log，发现关键信息：

...
211208  8:36:26 [ERROR] MysqLd: Can't create/write to file '/var/run/mariadb/mariadb.pid' (Errcode: 13)
211208  8:36:26 [ERROR] Can't start server: can't create PID file: Permission denied
211208 08:36:26 MysqLd_safe MysqLd from pid file /var/run/mariadb/mariadb.pid ended
...

检查权限

以上说明文件/var/run/mariadb/mariadb.pid无法被创建和写入，经过一些检查，发现其他用户无权限对/var/run目录进行：

# cd /var
# ll
...
drwx------. 12 root root  256 Dec  8 09:43 run
...

一般来说，我们一般不会使用root去启动MysqL相关的服务，在部署的时候会独立创建一些MysqL的用户和用户组，用MysqL这个用户专职启动MysqL服务；

解决方法

#chmod -R 755 /var/run
# cd /var
#ll
...
drwxr-xr-x. 12 root root  256 Dec  8 09:43 run
...