Unexpected mkdocs build failure: not using project's installed mkdocs extensions.

[davidorme]

Details

• Read the Docs project URL: https://readthedocs.org/projects/safedata-validator
• Build URL (if applicable): https://readthedocs.org/projects/safedata-validator/builds/23590836/
• Read the Docs username (if applicable): https://readthedocs.org/profiles/DavidOrme/

Expected Result

I'm making sure a release branch builds MkDocs pages correctly on RTD. Recent releases on the same project built without problem. See for example, this build from last week, which succeeded:

https://readthedocs.org/projects/safedata-validator/builds/23516950/

Actual Result

The new code doesn't have any changes to the RTD configuration or build process, but it fails. The package is installed using poetry and the pyproject.toml file includes all of the packages required to build the documentation in the docs group. I use poetry install --with docs to install the package requirements.

Looking at the logs, both builds successfully install via poetry. The earlier successful build then gets to the build step: python -m pip install --upgrade --no-cache-dir mkdocs and immediately finds all the required packages that have been installed by poetry. The failing build gets to the same step and does not find those installs, so installs the RTD standard mkdocs suite of packages and not the extra requirements included in poetry. So it fails when mkdocs tries to use those extensions.

I can't see what is causing this - I don't think I've changed anything that impacts this!

[collindutter]

Also facing this issue, our builds using poetry are suddenly failing. Have also made no changes to RTD or Poetry configuration. In our case the error is:

ERROR   -  Config value 'theme': Unrecognised theme name: 'material'. The available installed themes are: mkdocs, readthedocs
ERROR   -  Config value 'markdown_extensions': Failed to load extension 'pymdownx.highlight'.
ModuleNotFoundError: No module named 'pymdownx'
ERROR   -  Config value 'plugins': The "glightbox" plugin is not installed

Aborted with 3 configuration errors!

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Edit: Appears to be related to #11150 and #11152. Updating poetry install to VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install resolved it.

[davidorme]

Thanks for that edit @collindutter, I hadn't seen #11152 and can confirm that using VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH poetry install resolves the issue for me.