[systemd-devel] systemd - cleaning of /var/run/

[Hajo Locke]

Hello List,

we use Ubuntu16 and systemd. I have following problem.
We use "mount --bind" to bind folder /var/run/mysqld to different custom 
folders. We use this to bind the mysql-socketfile into a ssh-chroot.

example:

mkdir mysqld
mount --bind /var/run/mysqld/ mysqld/
ls mysqld/
mysqld.pid  mysqld.sock  mysqld.sock.lock


When restarting mysql, then folder /var/run/mysqld is deleted and 
recreated. Result is that every mounted folder is loosing his content, 
because "mount --bind" does not find its source any more.

Is there a way to prevent systemd from removing /var/run/mysqld ? If 
possible this folder should be reused every time, just we know it from 
former init-deamons.
Otherwise i have to edit mysql.service file and insert a second 
ExecStartPost to run a script which corrects the bindings. This would 
fix the problem, but there would also be a short time where mysql-socket 
dependent commands can fail. Iam not happy with this workaround.
Do you have a suggestion?

Thanks,
Hajo