bug#52919: Hidden "disk-image-rw" files aren't deleted after use, filling $tmpdir

[Mathieu Othacehe]

Hello Leo,

> This is new. I think the issue was introduced with recent work on (gnu
> system image), perhaps from this commit:
>
> https://git.savannah.gnu.org/cgit/guix.git/commit/?id=da924796744bbb7b035a986fe5d28d8d613ff6af

Before that commit "guix system vm" was always producing volatile
images, regardless of the "--volatile" argument. The new behaviour is to
only produce volatile images if "--volatile" is passed.

This means that by default, "disk-image-rw" are created in /tmp so that
QEMU can operate on RW images. The side effect is that those big images
can fill /tmp pretty quickly as you noticed.

We could use the ~/.cache/guix directory instead to store those
images. We could also make "--volatile" the default and introduce a
"--persistent" argument instead. That would restore the previous "guix
system vm" behaviour.

WDYT?

Thanks,

Mathieu