Can't connect to database

[dovecot at ptld.com]

>> mysql(localhost): Connect failed to database (postfix): Can't connect
>> to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

> Maybe MySQL is not running, or perhaps something is blocking connecting to it? Check dmesg and (if on redhat based system)
> /var/log/audit/audit.log


Environment? Chroot, docker, selinux can prevent sockets from being reachable.
Another area to check... when the socket has rwx for others, if one of the parent directories is blocking access for others then programs will be denied access.