Bug#920692: Packages must not install files or directories into /var/cache

[Josh Triplett <josh@joshtriplett.org>]

On Tue, Jan 29, 2019 at 01:20:31PM +0000, Ian Jackson wrote:
> Ian Jackson writes ("Re: Bug#920692: Packages must not install files or directories into /var/cache"):
> > Josh Triplett writes ("Bug#920692: Packages must not install files or directories into /var/cache"):
> > > It's well-established in Debian (but not documented in Policy) that
> > > packages must not install files or directories under /var/cache.
> > 
> > I think `install' is a bit less clear than it should be.  I think it's
> > clearer when you say `ship'.
> 
> Also: do we really need to say this in policy ?  Those three packages
> are almost certainly violating the FHS rule, which is imported by
> reference,

I carefully read the FHS, and while it mentions that software must
recover from deletion of files in /var/cache, it doesn't suggest
anything about not shipping files in /var/cache. While it's possible to
reason your way to "this is probably not a good idea" (don't ship files
that the sysadmin is allowed to delete, as that would lead tools like
debsums to flag them as missing from the package), as far as I can tell,
there's nothing in Policy *or* the FHS that proscribes this.

> and probably just filing bugs will fix it.

I have filed bugs already on the packages that didn't already have them.
In one such bug, the response asked where this was documented.

> It only *needs*
> to state things which are not otherwise clear,

I don't believe this is "otherwise clear" from existing policy.

> though it is of course
> useful for it to mention *common* bugs.  3x in Debian doesn't seem
> common to me.

Policy changes should not in general make packages instantly buggy; if
this were more common it wouldn't yet be appropriate to propose this
policy change. :)

It's worth documenting things that some packages have gotten wrong when
the reason why they're wrong isn't obvious and isn't currently
documented anywhere.