PEP 796: Relative Virtual Environments

[rickeylev]

Basic requirements (all PEP Types)

• Read and followed PEP 1 & PEP 12
• File created from the latest PEP template
• PEP has next available number, & set in filename (pep-NNNN.rst), PR title (PEP 123: <Title of PEP>) and PEP header
• Title clearly, accurately and concisely describes the content in 79 characters or less
• Core dev/PEP editor listed as Author or Sponsor, and formally confirmed their approval
• Author, Status (Draft), Type and Created headers filled out correctly
• PEP-Delegate, Topic, Requires and Replaces headers completed if appropriate
• Required sections included
  • Abstract (first section)
  • Copyright (last section; exact wording from template required)
• Code is well-formatted (PEP 7/PEP 8) and is in code blocks, with the right lexer names if non-Python
• PEP builds with no warnings, pre-commit checks pass and content displays as intended in the rendered HTML
• Authors/sponsor added to .github/CODEOWNERS for the PEP

Standards Track requirements

• PEP topic discussed in a suitable venue with general agreement that a PEP is appropriate
• Suggested sections included (unless not applicable)
  • Motivation
  • Rationale
  • Specification
  • Backwards Compatibility
  • Security Implications
  • How to Teach This
  • Reference Implementation
  • Rejected Ideas
  • Open Issues
• Python-Version set to valid (pre-beta) future Python version, if relevant
• Any project stated in the PEP as supporting/endorsing/benefiting from the PEP formally confirmed such
• Right before or after initial merging, PEP discussion thread created and linked to in Discussions-To and Post-History

Work towards python/cpython#136051

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📚 Documentation preview 📚: https://pep-previews--4476.org.readthedocs.build/

[hugovk]

Hello, before we go any further with this PR, has the idea been discussed on Discourse?

And after that we'll need a sponsor before assigning the PEP number, do you have one yet? Let's unassign 796 for now.

Please see:

• https://peps.python.org/pep-0001/#start-with-an-idea-for-python
• https://peps.python.org/pep-0001/#submitting-a-pep

[rickeylev]

Thanks @hugovk and @StanFromIreland for the early review. I used a draft PR to see the CI results to further clean it up -- my apologies for wasting some of your time, but thank you regardless.

discussed on Discourse?

Yes: https://discuss.python.org/t/making-venvs-relocatable-friendly/96177

The criteria of "discussed enough with enough support" is vague, but what gave me enough confidence to begin a PEP and start a (draft) PR at this point was:

• The thread didn't go totally off the rails (i.e. voracious disapproval)
• Positive statements from @ncoghlan in https://discuss.python.org/t/making-venvs-relocatable-friendly/96177/21 and gh-135773: have pyvenv.cfg without home key anchor a venv and deduce home cpython#135831 (comment)

Sponsor needed to assign number

Thanks for clarifying that part! Yes, finding a sponsor is my next big step.

[hugovk]

I used a draft PR to see the CI results to further clean it up

Tip: you can enable GitHub Actions at https://github.com/rickeylev/peps/actions and run the CI on your fork.

Yes, finding a sponsor is my next big step.

Good luck!

[AA-Turner]

@paveldikov thank you for the comment, please could you re-post it on Discourse? The peps repo / PR discussion is mainly for editorial discussion, rather than substantive comment on the proposal itself.

A

[rickeylev]

Thanks for the reviews! I'm out from under $dayJob and vacation backlogs a bit now and addressed comments.

[StanFromIreland]

Some little notes

[ncoghlan]

Belatedly removed the DO-NOT-MERGE label (that was added pending the Discourse discussion and sponsorship of the PEP)

[AA-Turner]

The PEP is currently missing a Security Implications section, which I think should be added given that arbitrary directory traversal is permitted -- at the very least explaining why this is fine.

Several editorial notes, I think the Motivation & Rationale sections should be strengthened to focus on the benefits from relative environments, there is currently (I believe) a lot of assumed context.

The PEP also discusses at some length a broader proposal for reloacatable venvs. Is it worth considering making that the proposal here? I don't know the specifics, so it might be that the changes needed for 'relocatable' are too large to tackle in one go.

A

[rickeylev]

Applied suggestions and addressed a few comments; didn't have time to address everything, though.

[rickeylev]

Ok, all pending comments addressed (I think. The Github UI frequently tricks me 😂 )

PTAL

re: security section: added. At least, insofar as I understand your concern correctly.

re: motivation and rationale strengthening: Thanks! Yeah, honestly, a big issue I've had writing this that "Motivation" and "Rationale" are, to me at least, practically synonyms. I did my best to better separate "Why do this change at all?" (motivation) and "Implementation decision and why that decision" (rationale).

re: proposing relocatable venv in this pep: I added a section about why this pep limits its scope to just the core interpreter.

[ncoghlan]

A few editorial comments inline, but I think this is essentially ready for publication.

[ncoghlan]

Suggested change

	directory references (``./``) are resolved syntactically (i.e. not resolving
	directory references (``./``) are resolved lexically (i.e. not resolving

(I don't mind if this isn't accepted, I've just always referred to this style of resolution as lexical rather than as syntactic: python/cpython#124825

[ncoghlan]

This isn't an open issue, but rather than intentional omission. Perhaps just include a variant of this paragraph in the rationale subsection about not fully specifying portable virtual environments?

[hugovk]

Lint fix:

Alyssa's suggestion below is better.

[hugovk]

It might be useful to say where you will teach this. What docs will you update?

[hugovk]

Suggested change

	`rickeylev/feat.relative.pyvenv.home<https://github.com/python/cpython/compare/main...rickeylev:cpython:feat.relative.pyvenv.home>`__.
	`rickeylev/feat.relative.pyvenv.home
	<https://github.com/python/cpython/compare/main...rickeylev:cpython:feat.relative.pyvenv.home>`__.

Please could you also wrap some of the other long lines to 79 chars?

https://peps.python.org/pep-0012/#general

[ncoghlan]

I think these are the two items the PEP linter is picking up.

[ncoghlan]

@rickeylev I went ahead and applied the straightforward markup & grammar fixes in ae5a67f, so the remaining comments are the ones that aren't as simple to address.

@AA-Turner This will need a re-review from you at some point for the "Changes requested" flag.

[hugovk]

I think @AA-Turner is very busy right now and unavailable for re-review.

@ncoghlan The 3.15 feature freeze is two months away, so if you think this is ready, please resolve the remaining comments and merge this.

Then @rickeylev can open the Discourse discussion.

[ncoghlan]

@rickeylev I'm currently down as the Sponsor for this, but if you would like, I can promote myself to co-author, resolve the remaining comments (which are the ones I considered to go beyond editorial and more into design territory) and handle getting this discussed and ready for submission to the SC before 3.16.