Hi all, I am working on a custom ResourceLoader module whose style contents are compiled from Sass stylesheets. These Sass stylesheets take as input user-defined theme variables that affect the output. I am looking for a way to invalidate ResourceLoader URLs that include such style modules, when these variables change as a result of an user action—primarily so that the user can see their own changes. ResourceLoader will cache such style URLs for 5 minutes on the CDN and in the user’s browser cache, so by default the user would have to wait until their cached copy of styles expire before they would receive the updated version. Accordingly, I have tried to explore if following the document steps to empty one’s browser cache[1] after making changes would cause the browser to fetch the updated resource from the backend. Unfortunately, both Chrome and Firefox appear to send a “Cache-Control: no-cache” request header for the style URL if the page is hard refreshed, which seems to cause most CDNs (including WMF’s) to act as the source of truth and serve the asset from cache if it is already there, without triggering a backend fetch or conditional revalidation. In the case of a simple refresh, Chromium and derivatives will not trigger a conditional revalidation of resources including on a page since 2017,[2] so they just continue to use the asset that was already in the browser’s cache. Thus, the standard instructions for emptying one’s cache do not seem to be sufficient to allow the user to see the effect of their styling changes. Given the above, the only option I see that would allow the user to see the updated styles after modifying input variables would be to append a version hash to the style URL included in the page HTML—something which ResourceLoader does not currently do. Do you know of a better approach to this problem? Are there any examples in MediaWiki core or extensions that accomplish something similar? I have consulted the code for ResourceLoaderSiteStylesModule, but it does not seem to have any specific invalidation behaviour, nor does it use a version hash in style URLs in the page HTML, so it seems that any updates to it take 5 minutes to propagate. Thanks in advance! — [1] https://en.wikipedia.org/wiki/Wikipedia:Bypass_your_cache [2] https://bugs.chromium.org/p/chromium/issues/detail?id=505048 Cheers, Máté Szabó SOFTWARE ENGINEER +36 30 947 5903 Fandom Poland sp. z o.o. z siedzibą w Poznaniu, ul. Abp. A. Baraniaka 6 Sąd Rejonowy Poznań – Nowe Miasto i Wilda w Poznaniu, VIII Wydział Gospodarczy Krajowego Rejestru Sądowego, KRS 0000254365 NIP: 5252358778 Kapitał zakładowy: 50.000,00 złotych _______________________________________________ Wikitech-l mailing list Wikitech-l(a)lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikitech-l