Manual:$wgDebugLogGroups

Debug: $wgDebugLogGroups
Direct wfDebugLog() output for certain groups to files other than $wgDebugLogFile .
Introduced in version:	1.5.0 (r10598)
Removed in version:	Still in use
Allowed values:	(array of log group keys to filenames)
Default value:	[]
Other settings: Alphabetical | By function

Details

Set to an array of log group keys to filenames. If set, wfDebugLog() output for that group will go to that file instead of the regular $wgDebugLogFile . Useful for enabling selective logging in production.

If a group is configured in $wgDebugLogGroups, then all debug messages with the according group key will be logged to that file, also if $wgDebugLogFile is not set! With other words: If a group key is configured in $wgDebugLogGroups, messages will be written, even if an empty value of $wgDebugLogFile generally disables debugging.

Log destinations may be one of the following:

• false to completely remove from the output, including from $wgDebugLogFile.
• string values specifying a filename or URI.
• associative array with keys:
  • destination - desired filename or URI.
  • sample - an integer value, specifying a sampling factor (optional)
  • level - A \Psr\Log\LogLevel constant, indicating the minimum log level (optional, since 1.25)

When $wgMWLoggerDefaultSpi is set to a non-default value, $wgDebugLogGroups will probably be ignored, and the method of configuring log files will be determined by whatever logging system is invoked by $wgMWLoggerDefaultSpi.

Example

This example logs debug messages of group "ConfirmEditExtension" to "debug-ext_confirmedit.log" and those of group "SpamRegex" to "debug-spam.log".

$wgDebugLogGroups = [
	'ConfirmEditExtension'	=> $IP . '/../../home/debug-ext_confirmedit.log',
	'SpamRegex'		=> $IP . '/../../home/debug-spam.log',
];

Example:

$wgDebugLogGroups['redis'] = '/var/log/mediawiki/redis.log';

Advanced example:

 $wgDebugLogGroups['memcached'] = [
     'destination' => '/var/log/mediawiki/memcached.log',
     'sample' => 1000,  // log 1 message out of every 1,000.
     'level' => \Psr\Log\LogLevel::WARNING,
 ];
 $wgDebugLogGroups['redis'] = [
     'destination' => '/var/log/mediawiki/redis.log',
     // Level can also be the literal string value of any Psr\Log\LogLevel constant
     'level' => 'info',
 ];

Multiple log groups in a single file

You might want to setup a temporary configuration like the following to see all authentication related logging to trouble-shoot authentication.

$wgDebugLogGroups['cookie'] =
	$wgDebugLogGroups['session'] =
	$wgDebugLogGroups['SimpleSAMLphp'] =
	$wgDebugLogGroups['PluggableAuth'] = "$IP/cache/PluggableAuth.log";

Some common debug log groups

• exception, error, fatal - errors
• deprecated - deprecation warnings
• objectcache, caches, memcached/SQLBagOStuff - cache
• rdbms - database (including, if $wgDebugDumpSql is set, all DB queries)
• cookie - response cookies
• exec - shell commands
• session - SessionManager
• authentication, login - AuthManager
• ratelimit, throttler - hitting rate limits ($wgRateLimits and other)
• resourceloader, ResourceLoaderImage - ResourceLoader
• http, HttpError - HTTP requests to external services (via the Http/MwHttpRequest classes)
• api - API
• thumbnail, fileupload, fileconcatenate - image-related
• runJobs - Job queue
• parser, ParserCache - Parser
• slow-parse - warnings about pages that take long to parse