Re: Modifying squashfs usage for `guix pack` for supporting singularity

[Ludovic Courtès]

Hi Josh,

Apologies for the delay!  (In general, it’s probably safer to report
bugs to address@hidden because they’re tracked and are less likely to
fall through the cracks.)

Josh Marshall <address@hidden> skribis:

> I ran into some trouble today when trying to package an image for singularity 
> on CentOS7.  nxck suggested I go into the cdoe and try adding the "-noappend" 
> option to mksquashfs in 'guix/guix/scripts/pack.scm'.  While looking at it, 
> it seems that it performs a multistep process to modify the squashfs image, 
> which kind of goes against the design of the utility.  A SO page ( 
> https://unix.stackexchange.com/a/459372 ) suggested the full hierarchy be 
> created and then added in a single invocation.  Does anyone have any opinions 
> on such a change or useful insights?

[...]

> It also appears the `-mkfs-time 0`, `-all-time 0`, and `-UTC` arguments have 
> been missing.

Could you explain what error you got and what makes you think these
options were missing?

IME, the images produced by ‘guix pack -f squashfs’ work fine with
Singularity 2.x and 3.x.

> Docker and Singularity havebeen moving towards support of the Open Containers 
> Initative, which prompts the discussion of if the docker and sinfularity 
> (squashfs) pack options should be depricated in favor of this standard: 
> https://github.com/opencontainers/image-spec

In fact, ‘guix pack -f docker’ produces an OCI image, IIUC.

Singularity 3.x introduced the Singularity Image Format (SIF), which is
yet another format.  AIUI, SIF is the recommended format for Singularity
3.x, isn’t it?

Thanks,
Ludo’.