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

[Ludovic Courtès]

Hi Josh,

Josh Marshall <address@hidden> 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’.