test.wikipedia.org
test.wikipedia.org is a special wiki that bypasses Varnish caching and runs from a single Apache server.
Purpose
Testwiki is intended primarily for:
- Short-term testing of code right before you push it to the rest of the wikis.
- Debugging issues in production.
- Long-term testing of configuration options or extensions that aren't enabled by default.
Details
Varnish redirects traffic intended for test.wikipedia.org or with a X-Wikimedia-Debug header set to one dedicated Apache server (mw1017, as of July 2013) and disables Varnish caching. As Trying tin's code on testwiki in How to deploy code explains, to test your changes on testwiki you get them on tin, then run sync-common on mw1017. Note that any changes you make this way will be overwritten by the next scap or sync. So, long-term changes should go into a block wrapped in an if ( $wgDBname === 'testwiki' ) (to prevent them from accidentally being synchronized to all servers!). Short-term changes (anything not committed to the git repo) should either be committed and rolled out, or reverted as soon as possible.
testwiki is configured to $wgShowExceptionDetails and to log wgDebugLog() output.
It has additional special configuration in InitialiseSettings.php.
Prior to around 2013 testwiki ran the MediaWiki code in /home/wikipedia/common mounted over NFS from fenari. Now it runs the same code as other Group 0 wikis, except when someone syncs to it as described above.