Re: [EXTERNAL]Re: Modifying squashfs usage for `guix pack` for supporting singularity

[Josh Marshall <Josh.Marshall@jax.org>]

Glad to have contributed :)

________________________________________
From: Ludovic Courtès <ludovic.courtes@inria.fr>
Sent: Friday, March 13, 2020 12:38 PM
To: Josh Marshall
Cc: guix-devel@gnu.org
Subject: Re: [EXTERNAL]Re: Modifying squashfs usage for `guix pack` for supporting singularity

Hi Josh,

Josh Marshall <Josh.Marshall@jax.org> skribis:

> While the images seem to work well in most cases, removing ways for bits to change seems to be in the spirit of guix, and so the "-all-time" and "-mkfs-time" options remove one source of change.  Additionally, without the "--no-recovery" an extra file is made which is not useful to the process, and for my manual testing seemed to cause write or permission issues which could cause failures.  Guix already handles the failure cases in mksquashfs which the recovery file is for and so the redundant work is not helpful, can cause problems, slows down the process, and requires more resources.

Oh, I hadn’t understood that there were reproducibility issues with
‘guix pack -f squashfs’, sorry about that!

Commits 24fb0dc0ab34ebb49509a3d5b4d84d8488670807 and
b829864d747b3b24ef37cafe36e889527b060d4d implement what you suggest.

I can confirm that now something like:

  guix pack -f squashfs sed --rounds=2

passes, which was not the case before.

Thanks!

> As for the information given by `guix pack --list-formats`, I'd change to something like the following:
>
> ```
>   tarball       Self-contained tarball, ready to run directly on any Linux machine
>   squashfs      Container suitable for Singularity 2.x and 3.x
>   OCI       OCI compliant tarball ready for 'docker load' and usable by Singularity 3.x
>   sif         Unsupported; container preferred by Singularity 3.x

We cannot change the format name, for compatibility reasons, but I’ll
double-check that what ‘-f docker’ produces is indeed OCI, and if so,
add it to the description.

> For more information, refer to https://guix.gnu.org/manual/en/html_node/Invoking-guix-pack.html

I don’t think we’re going to add references to the manual in --help and
similar: it’s always implicit that documentation is in the manual.
However, perhaps we could add terminal hyperlinks to make it more
discoverable.

Thanks,
Ludo’.
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