Currently Varnish attempts to prevent cachebusting on upload.* URLs by stripping query parameters and double slashes. However, that's not enough for thumbnails, where multiple URLs can point to the same thumbnail, by virtue of having a no-op part of the thumbnail URI (the repeated filename).
This could be easily prevented by normalizing thumbnail request URIs further in Varnish.
| Status | Subtype | Assigned | Task | ||
|---|---|---|---|---|---|
| Declined | None | T269946 Enable webp thumbnails on all images for non-Commons wikis | |||
| Open | None | T211661 Automatically clean up unused thumbnails in Swift | |||
| Resolved | • Gilles | T216339 Normalize thumbnail request URLs in Varnish to avoid cachebusting |
Change 491215 had a related patch set uploaded (by Gilles; owner: Gilles):
[mediawiki/vagrant@master] Normalize thumbnail request URLs in Varnish
Change 491215 merged by jenkins-bot:
[mediawiki/vagrant@master] Normalize thumbnail request URLs in Varnish
Change 495243 had a related patch set uploaded (by Gilles; owner: Gilles):
[mediawiki/vagrant@master] Normalize abbreviated case + remove redundant ext
Change 495643 had a related patch set uploaded (by Gilles; owner: Gilles):
[operations/puppet@production] Normalize thumbnail URLs to avoid cachebusting
Change 495243 merged by jenkins-bot:
[mediawiki/vagrant@master] Normalize abbreviated case + remove redundant ext
Change 495643 had a related patch set uploaded (by Ema; owner: Gilles):
[operations/puppet@production] Normalize thumbnail URLs to avoid cachebusting
Change 495643 merged by Ema:
[operations/puppet@production] Normalize thumbnail URLs to avoid cachebusting
This has caused a spike of thumbor thumbnailing requests, by virtue of making some objects hotter through deduplication, making them pass the webp hotness threshold.
Things seem to have stabilised for now, but the level of thumbnails generated is still higher than usual and will remain at a higher level for some time. Maybe even permanently, as a result of the hotness criteria being met more often.