Meza/Ensuring users get the latest file

= The problem = after you "Upload a new version of this file" for an image .. pages that use scaled versions of the image do not automatically get new the new image without some manual per-page coercing by the users .. how can you guarantee that users will always see the "current version" of an image after it has been updated?

= The solution = tools and solutions listed so far include;
 * 1) https://httpd.apache.org/docs/current/mod/mod_expires.html
 * 2) https://wikitech.wikimedia.org/wiki/Tool:Stashbot
 * 3) Tuning MW when using "img_auth.php"
 * 4) Resolve Bug: https://phabricator.wikimedia.org/T19577
 * 5) configure a for images, and use the headers module to add headers http://httpd.apache.org/docs/current/mod/mod_headers.html#header
 * 6) https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control has other caching possibilities

Which of these options and how to configure them is still a topic of discussion. If you have any specific solution that works for you.. please contribute to this page.