upload.wikimedia.org
upload.wikimedia.org is the hostname used for access to original and scaled-down media files for the Wikimedia projects.
MediaWiki
The MediaWiki software is configured at WMF to read-write user generated media files to Swift backends (see wmf-config/filebackend)). Each wiki has its own Swift bucket, and these are exposed through an Nginx proxy at upload.wikimedia.org. For example, files from English Wikipedia (en.wikipedia.org) are served from upload.wikimedia.org/wikipedia/en/*.
Users mainly upload files through the UploadWizard feature on commons.wikimedia.org. For read-access, the Special:Filepath shortcut redirects to the appropiate path on upload.wikimedia.org.
On private wikis, media files are not served from "upload.wikimedia.org", but instead served through the img_auth.php MediaWiki entry point from the private wiki's own domain name (which enforces authentication and access control).
Thumbor
Media storage
