Python: maintaining requirements.nix and requirements.txt?

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I’ve been experimenting with using nix to manage the development environment for a python-based web app. I initially generated a requirements.nix with pypi2nix but needed fairly significant manual updates to get everything sorted.

I’m pretty happy with how this works, but I’m leery of the potential for mistakes/divergence introduced by having separate authoritative definitions for packages installed in my personal dev environment and the production environment.

Does anyone have or know of good tooling/patterns for maintaining a single authoritative source?

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I hope that pypi2nix will be able to cache results of single packages at some point. At the moment when a failure, one has to start from the beginning, which takes too much time on complex projects.

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For what it’s worth, I have had good results to date using GitHub - datakurre/setup.nix: Nixpkgs based build tools for declarative Python packages [maintainer=@datakurre] (which adds some useful helper functions on top of pip2nix (this one GitHub - johbo/pip2nix: Freeze pip-installable packages into Nix expressions [maintainer=@datakurre] )

I’ve not worked with GitHub - nix-community/pypi2nix: Abandoned! Generate Nix expressions for Python packages so cannot speak to it

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Thanks for pointing out setup.nix. I’m not sure it will quite solve my immediate concern, but I can think of some other ways to put it to use.

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Consider this comment obsolete. There are now good documented options in nixpkgs manual.

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FWIW, I’m now happily managing the project mentioned here with mach-nix with most dependencies still specified in requirements.txt.

I never did share the requirements.nix version with the other developer on the project, but the mach-nix version has been stable enough for us to share even though he has minimal Nix knowledge.

I haven’t had time to evaluate whether moving to dream2nix is ripe yet.