Configuration database

From MediaWiki.org

[edit] Problems to solve

• .php config files are fragile
  • easy to break by mistake
  • no edit history unless you explicit do external version control
• Editing config files is difficult/inconvenient for many sites
  • requires shell access
  • can't easily expose limited settings to admins on the wiki, making serious bottlenecks for site config issues on a big wiki farm
• Handling config for multi-wiki farms right now is very difficult
  • SiteConfig/InitaliseSettings stuff is weirdly Wikimedia-specific and just plain ugly
  • querying settings from a sister site (even simply translating dbname <-> URL and getting descriptive names) is very difficult, unreliable (various settings may be in CommonSettings and not show up in the config arrays)
  • extensions are difficult to configure since the array is read in before the extensions and their defaults are loaded

[edit] Requirements

• Should work cleanly for one-off installs
• Should handle Wikimedia-style farms:
  • global configuration
  • configurations shared among project groups
  • configurations specific to a wiki
  • need to be able to fetch config info from other wikis cleanly
  • Varying user permissions; not all settings should be editable by everyone
• Metadata...
  • For each config (core or ext) provide:
    • type
    • validation rules
    • friendly name
    • more detailed description, examples
    • Default
• Needs high-level read/write support, so we can abstract backends more easily (CDB,SQL,etc)

Possibly use HtmlForm or similar framework for defining UI paging? Similar to prefs rewrite?

• We can adapt some of the form field types in Configure (that's where I got the idea for HTMLForm) for the new configuration (there are some specialist types like group permissions arrays).

[edit] Data types

• bool
• int
• string
  • email
  • URL
  • local path
  • message key
  • other
• wiki reference
• array of strings
• array of items
•  ?

[edit] Internal interface

Common case: local lookups:

• wfConf('serverUrl') (shortcut)
• WikiConfig::forLocal()->get('serverUrl')

Other-local-site info lookups:

• WikiConfig::forWiki('dewiki')->get('serverUrl')
• WikiConfig::forSite('de.wikipedia.org')->get('serverUrl') ?

interface WikiConfig {
 
	/**
	 * Get a configuration value, like 'wgEnableSomething'
	 * @param $key String A configuration key
	 * @return mixed
	 */
	public function get( $key );
 
	/**
	 * Set a configuration variable
	 * @param $key String A configuration key
	 * @param $value mixed The value to set
	 * @return mixed Previously set value
	 */
	public function set( $key, $value );
 
	/**
	 * Is a particular extension installed? Helpful
	 * for other extensions that might potentially change
	 * behavior if other extensions are installed
	 * @param $name String Extension name
	 * @return boolean
	 */
	public function extensionInstalled( $name );
 
}

[edit] User interface

There's a lot that can be adapted or copied from Configure.

[edit] Bugs that could be solved / New features

• bug 12518 - Cross-wiki userrights reflects groups on local wiki, not target wiki
• Maybe add a iw_wiki col in the interwiki table that references the wiki ID:
  • bug 11 - Red interwiki links -- check for page existence across wikis
  • bug 9890 - Reasonably efficient interwiki transclusion
    • (these sorts of things benefit from being able to look up things like remote namespaces cleanly, so we can pull data from a db directly instead of doing some nasty api hack)
  • Drop $wgLocalInterwiki and check if iw_wiki == wfWikiId().
• Maybe run internal HTTP requests (transwiki imports, fetching remote file description page, interwiki transclusion) internally?
• Drop $wgLocalDatabases and replace this with a query in the database.

[edit] See also

• module registry idea notes
• Extension:Configure experience and lessons
• Zend_Config