On 03/09/12 02:59, Tim Starling wrote:
I'll go for option 4. You can't delete the
images from the backend
while they are still in Squid, because then they would not be purged
when the image is updated or action=purge is requested. In fact, that
is one of only two reasons for the existence of the backend thumbnail
store on Wikimedia. The thumbnail backend could be replaced by a text
file that stores a list of thumbnail filenames which were sent to
Squid within a window equivalent to the expiry time sent in the
Cache-Control header.
The other reason for the existence of the backend thumbnail store is
to transport images from the thumbnail scalers to the 404 handler. For
that purpose, the image only needs to exist in the backend for a few
seconds. It could be replaced by a better 404 handler, that sends
thumbnails directly by HTTP. Maybe the Swift one does that already.
-- Tim Starling
The second one seems easy to fix. The first one should IMHO be fixed in
squid/varnish by allowing wildcard purges (ie. PURGE
/wikipedia/commons/thumb/5/5c/Tim_starling.jpg/* HTTP/1.0)
A wiki with such setup could then disable the on-disk storage.