Build: expose location of virtualenv

[davidism]

I'm using the PDM dependency management tool, moving away from requirements.txt files. If PDM does not detect an active virtualenv, or is not told about the location of a virtualenv, it will create one and install packages there.

Read the Docs does not activate or expose the path to the virtualenv it creates. It seems that which python does report the virtualenv python despite that, so a hack is used to get the path and tell PDM about it. pdm-project/pdm#1365 (comment)

VIRTUAL_ENV=$(dirname $(dirname $(which python))) ~/.local/bin/pdm sync -dG docs

It would be helpful if Read the Docs made the virtualenv easier to find. You could set VIRTUAL_ENV, or maybe RTD_VIRTUAL_ENV if you don't want to affect other tools by default. Alternatively, activate it.

• Read the Docs project URL: https://readthedocs.org/projects/flask-sqlalchemy/
• Build URL (if applicable): https://readthedocs.org/projects/flask-sqlalchemy/builds/18192947/
• Read the Docs username (if applicable): https://readthedocs.org/profiles/davidism/

[humitos]

Hi @davidism! I don't have experience working with PDM, so maybe what I'm going to suggest makes no sense 😄

However, for Poetry users that have a similar situation where the "feature of auto-creation of the virtualenv interferes with Read the Docs default build workflow" we documented a workaround for that at https://docs.readthedocs.io/en/latest/build-customization.html#install-dependencies-with-poetry. I saw that PDM does support something similar https://pdm.fming.dev/latest/usage/venv/#disable-virtualenv-mode

That solution/workaround does work for your case?

[davidism]

In PDM, disabling virtualenv support means enable the old __pypackages__ PEP, which won't solve the issue either. There is no way to completely disable venv support as far as I know. Maybe @frostming can say more, but I'm guessing that would have been suggested in the linked PDM issue if it were possible.

[davidism]

@davidfischer @ericholscher This is the virtualenv feature I was talking about yesterday.

[ericholscher]

Gotcha, I was going to suggest something like VIRTUAL_ENV=$(dirname $(dirname $(which python))) as a workaround, since we do run via the Python executable. I agree that adding an ENV for this would be useful, but that's not the worst workaround for now.

[davidism]

I'm planning to switch Flask, Click, etc. to PDM soon. It would be nice to be able to directly reference the virtualenv location. What's the status of work on this?

[ericholscher]

@davidism I will add this to our upcoming sprint so we can take a look at it. I think it's reasonable to add it to the environment, and won't be complex, but mostly just need to do the PR 👍

[humitos]

I went ahead and implemented this feature in #9971. Hopefully, we can review it this week and deploy it the next one.

Considering flask-sqlalchemy and 1107 version as example, the value of this variable will be: /home/docs/checkouts/readthedocs.org/user_builds/flask-sqlalchemy/envs/1107. @davidism let me know if that would be accurate for your use case.

[davidism]

@frostming does this look correct?

[frostming]

LGTM

[davidism]

Will you close this once it's deployed? Or is it ready for me to test?

[ericholscher]

@davidism It should go out in our deploy next week on Tuesday. This issue will likely get closed once the issue is merged, but Tuesday is the day :)

[humitos]

@davidism @frostming This is already deployed. You should be able to make usage of the variable READTHEDOCS_VIRTUALENV_PATH now from your build commands. Let me know if this works as you expected 👍🏼

[davidism]

Looks like it worked: https://readthedocs.org/projects/flask-sqlalchemy/builds/19424647/ thanks!