tmpdir for Debian/Ubuntu and the way forward

[arif-ali]

Following on from #4074 it makes sense to get a sense of why Debian/Ubuntu should be different to other distros and that we have the tmpdir to be /tmp

This has been discussed in 2 issues in the past both from 2020, and well before I got involved with project (I got involved in Apr 2022)

• Determine if Ubuntu/Debian should default to /var/tmp or back to /tmp #1997
• sos now enforces /var/tmp as tmpdir unless --tmp-dir option is used #2178

Ultimately it seems at the time the cleaning of sos from the directory was not happening, and /var/tmp cleaning wasn't there, hence effectively leaving them there, and the drive could fill up if more sosreports were created.

Now, it seems like now, (5 years later), 2 commits have caused issues due to the fact the /etc/sos/sos.conf doesn't get shipped with tmp-dir = /tmp due to the fact I added as default for Debian/Ubuntu. Furthermore while testing anoter PR later, we found that the policy was not being enforced at all, and everything was being defaulted to /var/tmp, and hence the issue raised in #4074.

These 2 changes were made to lift all the debian patches so that we are as close to upstream as possible.

So moving to now, the file /usr/lib/tmpfiles.d/tmp.conf does have a 30d cleanup of /var/tmp similar to other distros in the most recent distros

Looking through the previous issues, it was found that the following was in /usr/lib/tmpfiles.d/tmp.conf for old distros, so didn't make sense to have sos go into /var/tmp, as that would never had cleaned up. This is an example of the 2 current Ubuntu LTS releases i.e. jammy and noble

<snip>
# Clear tmp directories separately, to make them easier to override
D /tmp 1777 root root -
#q /var/tmp 1777 root root 30d

Looking at the most recent distro (plucky) I see the following

<snip>
# Clear tmp directories separately, to make them easier to override
q /tmp 1777 root root 10d
q /var/tmp 1777 root root 30d

This means that the next LTS which is due in April 2026 will have this there, and hence we can potentially streamline this. This gives us enough time between intermediate releases to enable this change and bring this in an intermediate release.

Looking at the Debian releases, the current stable release is the same as jammy and noble, and it doesn't cleanup /var/tmp at all, as the file is identical. The release due soon (and in hard freeze now), does update it to the second output above, and does clean after 30 days.

So, moving forward I think it makes sense that we update upstream to default to /var/tmp, plucky and above to follow suite; and then once the hard-freeze is over, I can back-port that to Debian trixie

On another note, Even though there were discussions of cleaning up tmpfiles in one of the issues above, this was never implemented by Debian/Ubuntu, and I think it should of. Well, at least it now would make sense to enable that for both Debian/Ubuntu once we go to /var/tmp. Looking at the spec file, this is already being implemented by Fedora/RH.

Hopefully that's a good summary of where we are, and open this up for discussion

[martinpitt]

Thanks for the analysis! Indeed makes sense to unify this across distributions, so that documentation, UIs, blog posts, and tools wrapping sosreport all work without special cases.

[arif-ali]

We have a way forward, we will ship the sos.conf as previously for jammy, noble and plucky with tmp-dir set to /tmp. questing and above will default to /var/tmp and no config file being shipped

@martinpitt you should see an update soon once the package is approved into plucky and goes into proposed, I am sorry that this caused an issue for cockpit

[martinpitt]

Thanks @arif-ali ! Don't be sorry, that's fine -- I'm glad that it led to discussing that and cleaning it up for the long term, really appreciated! 🤗