Re: Replicable environment with Python packages missing from Guix

[Simon Tournier]

Hi,

On Thu, 05 Oct 2023 at 15:00, Lasse Schlör <lasse.schloer@uni-tuebingen.de> 
wrote:

> Currently, no PsychoPy package exists for Guix, and so I attempted to
> write my own Guix packages for PsychoPy and those of its dependencies
> that don't exist as Guix packages either.

Well, sadly Guix cannot fix the world. :-) Here, PsychoPy is poorly
packaged in PyPI, thus there is no easy way to write Guix recipe for it.

--8<---------------cut here---------------start------------->8---
$ guix import pypi PsychoPy -r

Starting download of /tmp/guix-file.6lTxL2
>From 
>https://files.pythonhosted.org/packages/16/17/a73ebae6cfcbd6f4cf094fba59b17f1ca1b03b6a8c0afdaa11468bc3fe62/psychopy-2023.2.3.tar.gz...
 …3.2.3.tar.gz  34.3MiB               550KiB/s 01:04 ▕██████████████████▏ 100.0%
guix import: warning: Cannot guess requirements from source archive: no 
requires.txt file found.
(define-public python-psychopy
  (package
    (name "python-psychopy")
    (version "2023.2.3")
    (source (origin
              (method url-fetch)
              (uri (pypi-uri "psychopy" version))
              (sha256
               (base32
                "0mf3gas4892108c7y0n8sl7phkl6w2z4lgymb4n0d6h9p6g58mpq"))))
    (build-system pyproject-build-system)
    (home-page "")
    (synopsis
     "PsychoPy provides easy, precise, flexible experiments in behavioural 
sciences")
    (description
     "@code{PsychoPy} provides easy, precise, flexible experiments in 
behavioural
sciences")
    (license #f)))
--8<---------------cut here---------------end--------------->8---

All, and I do not see that packages in any of extra scientific channels:

    https://hpc.guix.info/channels/

but I can have overlooked.

> As a workaround, I have instead written a manifest file that provides
> a fixed version of Python, Pip, and some of PsychoPy's dependencies. I
> can use this to start a container with `guix time-machine […] -- shell
> --container --share=path/to/persistent/.local=/home/username/.local
> […]`, which has a persistent `~/.local` directory, into which the
> correct version of PsychoPy can be installed via `python3 -m pip
> install -r path/to/requirements.txt`. Making `~/.local` persistent
> allows to start new instances of this container without having to
> re-install PsychoPy every time.

If I understand correctly, here the only thing you will be able to
reproduce from one machine to another is ’python3’.  But you have no
guarantee that you will be able to reproduce ~/.local elsewhere.  Well,
based on my poor knowledge of ’pip’and PyPI.

However, that’s already good.  Because it means that if your
computations work in an isolated environment created with “guix shell
--container” then it means there is no leak to system-wide libraries.
And, to my knowledge, this kind of packages are easier to package. ;-)


> Of course, this doesn't feel as elegant as the purely functional Guix
> way of doing things. I am sure others before me have had similar
> situations. Thus, my question is: Is there a known/preferred/elegant
> way of creating replicable Guix environments with fixed versions of
> Python packages when these packages do not exist as Guix packages?

The only way to have replicable Guix environment is to fully control all
the chain, and thus, it means to have a Guix recipe for the packages.

However, as you are pointing, when packages are missing, I accept the
trade-off to work with language-specific package manager knowing that I
loose some guarantees for reproducing.  Trade-off. :-)



Cheers,
simon