Extension:CentralAuth

CentralAuth allows merging several existing separate account systems into one global account system.

Installation
See the setup section below for prerequisites to using CentralAuth. Then follow these instructions when you are ready to activate CentralAuth:


 * 1) Download the latest snapshot and extract it to your directory.


 * 1) Pick a database and create the CentralAuth database tables. You can use an existing database or create a new one; the extension by default uses a database named  (see  below).  Use this database then run.
 * 2) * If you use you'll need to create a global  table (to block new usernames that look similar to existing usernames in any wiki).  One way to do this is dump the  table from the local wiki's database and import it into the new.
 * 3) Add  to  for each of your wikis, or in another PHP file that is included in  on each of your wikis.
 * 4) The extension should be now active.

Here are sample shell and SQL commands to create the centralauth database, copy the spoofuser table to it, and migrate existing user data to it. Replace $wgDBname and $wgDBuser with the values for your own wiki installation.

Create the new database (Remember this step is optional, you can instead use one of your existing databases, in which case skip to the create tables step):

The following assumes your present working directory is your MediaWiki installation (not your CentralAuth directory). Create the central auth tables (using is preferred.

If AntiSpoof is installed, create the table via (Alternatively, you can copy an existing AntiSpoof table if you want to keep previous entries):

Run the user migration scripts

Upgrading
CentralAuth is designed for large wiki farms who run database updates manually in order to enable zero-downtime upgrades. For that reason, the CentralAuth database will not be updated with the usual upgrade process. Third-party users are expected to follow CentralAuth development and apply database migrations manually instead.

Setup
First, you'll need to configure your wiki family using, or CentralAuth can't be used for your wiki family. This includes setting and assigning it to , and  (minimum is  ,  and  ). Follow the examples carefully. Make sure that you put the configuration code after the line in. If you are creating a new wiki family, bear in mind that it may be easier if the databases for the wikis in each group have the same suffix (e.g. hypothetical databases,  ,  , etc., pertaining to wikis belonging to the same group, all have the suffix "  ").

After installing the extension, you have to gather some data in the CentralAuth database. In order to retroactively set up global accounts, you will have to run the and  scripts. The first one stores information about your wikis in the CentralAuth database, while the second one uses automatic migration heuristics to generate global accounts. A user can merge their accounts manually via Special:MergeAccount. Dry runs can be used for testing purposes.

To enable global groups, you will have to make an entry into the table in your CentralAuth database, with  and (for access to the group management interface). A sample query that is recommended to use is:. Then, run to promote local stewards to global steward status.

There are various settings you may wish to modify (e.g. whether to provide single sign-on across a whole domain) listed in. In particular, you will want to override the default value of if your CentralAuth database is named something other than. Make sure you put such settings after the line in , e.g.:

"SUL2" behavior
In July 2013 WMF changed its approach to logging users into multiple wikis. When configured for this new approach, after successful login and account creation CentralAuth redirects to on a "central login wiki", which sets cookies on that wiki and then redirects back to the logged-into wiki. It omits the "login/account creation success" page, instead redirecting back to the "returnto" page that the user was originally on. It places 1x1 pixel images in the footer of that page, in place of the icons formerly used on the "login/account creation success" page.

The settings for this are, roughly,

is the id (usually the database-name) of the wiki to which CentralAuth will redirect on login and create account.

Cache issues
For best results, it is recommended to use memcached. If you have only a single server, accelerator caches like APCu can also work, but do not use them if you have multiple servers. If you have no cache set up (i.e. ) for , or are using  , then you need to make sure all your wikis use the same caching table.

By default, each wiki in your wiki farm will use the table in its own database (with its own db prefix) when  is set to  or.

To make this work with CentralAuth, we need to tell the wikis to use a central cache table.

If you want to make a central caching table in the database (and assuming one of your existing wikis has a database name of  ), run code like the following to copy the table to your other database:

Then add the following config to all wikis to tell them to use the central table instead of their own table:

Use
Allows for a single-user login (SUL) system using MediaWiki's AuthPlugin system. User creation and login is done globally using one central user table across all wikis. Note that local user accounts are automatically created on account creation/login however.

This extension also implements global user groups, to which global accounts can belong to.

User rights
CentralAuth defines several new user rights:

Single-user login (SUL)
A user with an account on more than one wiki may use Special:MergeAccount to create their global user account, which can then be used on any wiki. Users with the permission (given to stewards by default) can undo a merging of a global account, where the passwords are all reset back to the pre-merge setting. User accounts can now also be renamed globally.

Locking and hiding global users
A global account can be locked or hidden by a user with the and  permissions, respectively, given to the local group 'stewards' by default. A locked global account will be immediately logged out of any session on any wiki it is currently logged in to. A hidden global account's username is not visible in any logs except the global account log.

Wiki sets
A wiki set is a group of wikis specified by a user with the right. Sets can be opt-in (wikis are not in it by default) or opt-out (wikis are in it unless opted out).

Global user groups
Once you have enabled global user groups as described in the installation section, a migrated steward can use the Special:GlobalGroupPermissions interface to configure global user groups, and their rights. A global user group is active on all wikis (the users in it have its rights on all the wikis) by default, unless the group has been specified to only be active on a specific wiki set (the users in the group only have the rights if they are on a wiki in the set). Global group permissions are not listed at Special:ListUsers, but instead Special:GlobalUsers. They are assigned by a user with the permission (by default the global group  ), and give the specified rights to the user even if the local rights defined by  do not do so.

Licensing and downloads
The extension is available under the GNU General Public License 2.0 or later, and can be downloaded from Git, or accessed via the.

The software is provided as-is. Updates will be made according to the needs of Wikimedia wikis; or where critical vulnerabilities are discovered.

API
See.