Hey all,
I'm writing to let you know of a cool new facility for debugging MediaWiki code on the Wikimedia production cluster -- the X-Wikimedia-Debug https://wikitech.wikimedia.org/wiki/X-Wikimedia-Debug HTTP header.
By setting this header on requests to Wikimedia wikis, you can:
- Bypass the cache. - Force Varnish to pass your request to a specific backend server. - Profile request and log profiling data to XHGui. - Turn on all log channels and send log messages to a special view in Kibana / Logstash. - Force MediaWiki to process the request in read-only mode.
And the best part: there are browser extensions for Chrome and Firefox that provide a friendly user-interface for these features:
http://i.imgur.com/XzWUk0h.gifv
http://i.imgur.com/lJ7l6Vl.gifv Cool? Cool.
Read the docs on Wikitech https://wikitech.wikimedia.org/wiki/X-Wikimedia-Debug for more information.