Redirects don't work if the url includes /projects/foo

[ltalirz]

Details

It seems that in exact redirects the $rest keyword is treated "verbatim" rather than as the placeholder it is intended to be.

The documentation on exact redirects explains

So, I tried setting up the following redirect on the aiida-core RTD project:

Expected Result

All requests of the form
https://aiida-core.readthedocs.io/projects/abc
should be redirected to
https://aiida.readthedocs.io/projects/abc

Actual Result

Only the "verbatim" request
https://aiida-core.readthedocs.io/projects/$rest
is redirected to
https://aiida.readthedocs.io/projects/

[humitos]

Hi! Thanks for your report. The /projects/ part of the URL has a special meaning in Read the Docs and it's used to define subprojects of a project. In your example, abc is a subproject of aiida-core. Read the Docs tries to find the abc subproject and fails. That's why it's returning 404.

The code that produces this is at

readthedocs.org/readthedocs/proxito/views/decorators.py

Lines 42 to 46 in 2d64328

	log.warning(
	'The slug is not subproject of project. subproject_slug=%s project_slug=%s',
	subproject_slug, kwargs['project'].slug
	)
	raise Http404('Invalid subproject slug')

That decorator is executed immediately when the page is tried to be served and the redirects code is not hit at all because the decorator fails:

readthedocs.org/readthedocs/proxito/views/serve.py

Lines 72 to 79 in 2d64328

	final_project, lang_slug, version_slug, filename = _get_project_data_from_request( # noqa
	request,
	project_slug=project_slug,
	subproject_slug=subproject_slug,
	lang_slug=lang_slug,
	version_slug=version_slug,
	filename=filename,
	)

I'm afraid that this is a current limitation about how redirects with /projects/ in the URL works.

Only the "verbatim" request
https://aiida-core.readthedocs.io/projects/$rest

This redirect works because $rest is interpreted as '' (empty).

1. RTD tries to access /projects/ page in a project with versions and it fails,

WARNING Invalid URL for project with versions. url=projects/, project=aiida-core [readthedocs.proxito.views.serve:122]

2. The 404 handler is triggered and found a redirect

Redirecting: from=https://aiida-core.readthedocs.io/projects/ to=https://aiida.readthedocs.org/projects http_status=302 [readthedocs.proxito.views.mixins:233]

(note that $rest does not appear in the from= URL)

[ltalirz]

Thanks a lot @humitos for the detailed analysis!

I see - I was trying to use the redirect in order to work around #7487 (i.e. to fix the broken links in the search results on aiida-core, which wrongly include the /project prefix).

This particular use case will go away once #7487 is fixed, but there is another use case that will remain: if a subproject moves away from a parent project, it would be very useful to be able to still redirect requests to a different documentation site - thanks for accepting this as a feature request.