Bug#966621: Make /tmp/ a tmpfs and cleanup /var/tmp/ on a timer by default [was: Re: systemd: tmpfiles.d not cleaning /var/tmp by default]

[Michael Biebl]

We have two separate issues here:

a/ /tmp-on-tmpfs
b/ time based clean-up of /tmp and /var/tmp

I think it makes sense to discuss/handle those separately.

Regarding a/:
tmp.mount as shipped by systemd uses the following mount options:
"mode=1777,strictatime,nosuid,nodev,size=50%"

In the past there were concerns that those 50% of available RAM wasn't a 
one-size-fits-all solution, especially for (LXC) containers and VMs

One also needs to keep in mind that debian-installer still offers a 
partitioning setup with /tmp on a separate partition. This will be 
created via an entry in /etc/fstab. Such a /tmp entry in /etc/fstab will 
override tmp.mount.

If we go with a/, then I think d-i should be updated to no longer create 
/tmp as a separate partition.


Regarding b/:
The current setup as used in Debian is to only clean /tmp on boot (which 
is pointless with /tmp-on-tmpfs) and never clean up /var/tmp

The tmpfiles rule tmp.conf as shipped by systemd upstream contains:

q /tmp 1777 root root 10d
q /var/tmp 1777 root root 30d

Files that are older then 10 days or 30 days are automatically cleaned 
up. The age of the files are determined as such:

"The age of a file system entry is determined from its last modification 
timestamp (mtime), its last access timestamp (atime), and (except for 
directories) its last status change timestamp (ctime). By default, any 
of these three (or two) values will prevent cleanup if it is more recent 
than the current time minus the age field."

I'm not sure if we have software on long running servers which place 
files in /tmp and /var/tmp and expect files to not be deleted during 
runtime, even if not accessed for a long time. This is certainly an 
issue to be aware of and keep an eye on.


Michael
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature.asc
Type: application/pgp-signature
Size: 840 bytes
Desc: OpenPGP digital signature
URL: <http://alioth-lists.debian.net/pipermail/pkg-systemd-maintainers/attachments/20240506/e1345146/attachment.sig>