You are probably reading wikitech right now

What/Where

Wikitech runs on the eqiad host 'silver'. The mediawiki install is updated automatically as part of standard WMF deployment. Nevertheless, it differs from a vanilla wiki in several ways:

Silver runs Ubuntu Trusty, but wikitech is hosted with standard Apache and php5, /not/ hhvm.
Images are hosted in a non-standard location: /srv/org/wikimedia/controller/wikis/images/
Auth on wikitech uses ldap accounts
A successful login on wikitech requires a token from Openstack Keystone in the labs cluster (currently Keystone runs on virt1000)
Wikitech runs the latest version of OpenStackManager for control of Labs.
Wikitech runs a very out-of-date version of SemanticMediaWiki

There are some MediaWiki config settings that are entirely exclusive to wikitech. These are set in a special .php config file: /srv/mediawiki/wmf-config/wikitech.php

Troubleshooting

In addition to normal ways to break (that any server or mw install is subject to), wikitech has a few additional failure cases due to relying on ldap and keystone. If login is failing, turn on the ldap+auth log by uncommenting some lines in /srv/mediawiki/wmf-config/wikitech.php:

 #$wgPasswordReminderResendTime = 0;
 #$wgPasswordAttemptThrottle = false;
 #$wgShowExceptionDetails = true;
 $wgLDAPDebug = 5;
 $wgDebugLogGroups["ldap"] = "/tmp/ldap-s-1-debug.log";

With that change, /tmp/ldap-s-1-debug.log will fill up with useful info, and you should be able to determine if ldap is breaking, or Keystone, or something else. wikitech.php will revert to its standard commented-out state during the next deploy cycle.

When you connect to silver, don't forget that it's a public box so can be reached at silver.wikimedia.org, not silver.eqiad.wmnet (but still via a bastion).