[Pkg-zsh-devel] Bug#844076: Bug#844076: zsh: FTBFS (failing tests)

[Santiago Vila]

[ Sorry for the late reply. I'll try to answer your questions the best I
  can, but the interesting thing is at the end: zsh does not FTBFS anymore ]

On Sat, 12 Nov 2016, Axel Beckert wrote:

> Hrm. A few questions, hopefully leading into the right direction:
> 
> * Can you show me the output of "mount" of such an overlayfs mount
>   point?

This is the output of "mount -l | grep schroot | grep overlay" on
a machine which is currently building packages with the feature enabled:

stretch-eatmydata on /run/schroot/mount/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66 type overlay (rw,relatime,lowerdir=/var/lib/schroot/union/underlay/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66,upperdir=/var/lib/schroot/union/overlay/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66/upper,workdir=/var/lib/schroot/union/overlay/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66/work)

This is, however, something that the end user (me in this case) does not
have to worry about. The way to enable overlayfs when using sbuild
is to add a line saying "union-type=overlay" to the file which
defines the chroot.

As an example, here is my /etc/schroot/chroot.d/stretch-eatmydata file:

[stretch-eatmydata]
type=directory
description=Debian stretch
directory=/chroot/stretch
groups=sbuild
root-groups=sbuild
preserve-environment=true
union-type=overlay
command-prefix=eatmydata

I can then "schroot -c stretch-eatmydata" or tell sbuild to use
"stretch-eatmydata" as the name of the chroot to be used.

[ The end result is that sbuild does not bother to uninstall
  the build-dependencies after the build. Official autobuilders
  do something similar with LVM but I never had the time to do it
  that way ].

> * Does overlayfs support atimes? If not, this the likelyhood that this
>   is a duplicate of #764650 is very high. If it supports atimes only
>   optionally, can you enable them in your build and see if the issue
>   vanishes?

I have no idea, sorry. Also, I would not even know how to enable it
in case it was optional. As I said before, this is something which
schroot handles for me automatically.

> * Can you verify that this failure is deterministic, i.e. do 10 builds
>   and see if all of them fail in the same way? (zsh unfortunately has
>   a history of occassional non-deterministic and hard to debug test
>   suite failures or hangs, see e.g. https://bugs.debian.org/760061)

This is where things get interesting :-)

The failure happened always when I first detected it (so yes, it was
deterministic). Today I tried again (a lot of times as well) and it
always built ok.

Then I tried "diff" on the build logs and found the variables required
to reproduce it: Using Linux 4.7 AND sbuild with overlayfs.

If you still want to reproduce this, I think it would still be
possible by getting linux-image-4.7 from snapshot.debian.org, but that
would be an exercise of "software archeologism".

Let's just say that overlayfs was not good enough in Linux 4.7.

I think this bug should be closed and maybe reassigned to linux as well
with an "affects src:zsh".

Thanks a lot.