This is great, and I'm sure many 3rd party installs will be glad of it
too (to reduce their thumb storage requirements).
A couple of times lately I've had the "429 Use thumbnail steps listed on
https://w.wiki/GHai"; message, and because I'm a bit slow on the uptake I
went looking for the steps to follow to get thumbnails. Has anyone else
been confused by this? If it's just me, ignore this, but perhaps we
could update the message to say "Use the values of $wgThumbnailSteps
listed on…" instead.
On 24/1/26 02:27, Amir Sarabadani via Wikitech-l wrote:
Thumbnails shown on-wiki are already quantized to a set of standard
sizes (if a non-standard size is requested, the next-larger standard
size is used, and scaled to the requested size by the browser). We
have recently extended the set of standard sizes, and are now moving
to only allow standard sizes to be used. Regular editing and viewing
will not be impacted by this change at all.
* What isn't changing?
Thumbnails served on wiki (via the "thumb" argument to File:, and via
the Media API) will continue to behave as they do now - if you request
a non-standard size, the next-larger standard size will be provided,
and scaled in-browser if appropriate.
* What is changing?
Requests for non-standard thumbnail sizes using other methods (e.g.
constructing an upload.wikimedia.org <http://upload.wikimedia.org> URL
with a non-standard thumbnail size) will be blocked by our CDN. These
are already being rate-limited for requests that we assess are not
coming from a web-browser.
During this quarter, we will be broadening the scope of the existing
rate-limiting and making it increasingly strict, with the aim being to
refuse such requests entirely by the end of March 2026.
* Why are WMF doing this?
Historically, we have generated thumbnails of whatever size was
requested; this has been a drain on our thumbnailing infrastructure
and cost us in network bandwidth and storage volume. With the
increasing prevalence of highly aggressive scrapers, this has become
an intolerable burden on our network, infrastructure, and staff, who
have spent a lot of time over the holiday period working hard to keep
the wikis available for people to read in the face of automated abuse.
* What do I need to do?
Most likely, nothing: we have already tracked down some of the more
widely-deployed sources of nonstandard thumbnail requests (e.g. Popups
extension) and fixed them. If you own or operate something that
requests thumbnails by constructing a thumbnail URI directly, then now
is the time to either use the Media API instead or to make sure you
only request standard thumbnail sizes.
* What are the standard thumbnail sizes?
They are: 20px, 40px, 60px, 120px, 250px, 330px, 500px, 960px, 1280px,
1920px, 3840px
They are defined in config as $wgThumbnailSteps -
https://gerrit.wikimedia.org/r/plugins/gitiles/operations/mediawiki-config/+/refs/heads/master/wmf-config/CommonSettings.php
And also documented on MetaWiki -
https://www.mediawiki.org/wiki/Common_thumbnail_sizes
To help fix the existing instances, please see
https://phabricator.wikimedia.org/T414805 for search-links, and
examples of how to fix them.
Best
--
*Amir Sarabadani (he/him)*
Staff Database Architect
Wikimedia Foundation <https://wikimediafoundation.org/>
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