Make Monolog the default debug processing layer and deprecate wfDebug* and LegacyLogger
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	• bd808
	Jan 17 2017, 9:22 PM

Description

Problem

The PSR3 logging interface has been introduced in MediaWiki to support structured logging, but no coordinated effort has been made to deprecate the use of wfDebug(), wfDebugLog(), wfLogDBError(), and wfErrorLog(). Several bugs are open in the MediaWiki-Debug-Logger project about the lack of parity between debug log usability on the Wikimedia Foundation production cluster and a typical development environment or external deployment of MediaWiki that are directly related to @bd808 taking the structured logging project to a point where it is useful for the WMF but not pushing that usability further for other MediaWiki deployments.

Who would benefit

MediaWiki site operators who want better insight into their operational issues
MediaWiki developers who don't want to think about choosing between two largely compatible but very different debug logging layers

Proposed solution

Replace all usage of wfDebug* in MediaWiki core with direct PSR3 usage.
Add Monolog as a core dependency and the default debug logging solution.
Make configuring Monolog easier by making helpers in the MediaWiki\Logger\Monolog namespace.
Remove MediaWiki\Logger\LegacyLogger from core. (It could be made a library if there are people who really love it and want to keep maintaining a homegrown debug log formatting and routing layer.)
Deprecate wfDebug(), wfDebugLog(), wfLogDBError(), and wfErrorLog().

Related Objects

Mentioned In: T142313: Add global information to debug logger context
T258755: Add rule against use unsafe use of Exception::getTraceAsString()
T193472: Log suppressed errors with level=DEBUG
T196906: Sensible default parameters for Monolog logging
T167942: Database::upsert() for Postgres triggers an (ignored) error, by design
T157756: Provide a way to use log events as metrics in MediaWiki core
Mentioned Here: T88649: Convert MediaWiki logging to direct use of PSR-3
T92585: MediaWiki logging/debugging documentation is out of date
T108650: $wgMWLoggerDefaultSpi requires special usage, needs to be fixed or documented
T114532: MWDebug toolbar log is empty when Monolog is enabled
T128224: It is difficult to determine in which log bucket a logging call will end up
T142313: Add global information to debug logger context

Event Timeline

• bd808 created this task.Jan 17 2017, 9:22 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptJan 17 2017, 9:22 PM

It would be worth explaining how people will benefit, so that developers unfamiliar with structured logging can tell whether this is important for them.

In T155552#2947209, @Tgr wrote:

It would be worth explaining how people will benefit, so that developers unfamiliar with structured logging can tell whether this is important for them.

The structured logging RfC outlines some of the perceived benefits generally:

Consistent mechanism to indicate log message severity (debug, info, warning, error)
Ability to add structured contextual data to log messages
Machine readable log output to enable de-duplication, alerting, reporting

From the point of view of the code base, deprecating the wfDebug* methods and replacing MediaWiki\Logger\LegacyLogger with Monolog reduces the lines of code and number of debug logging abstractions in core.

Jdforrester-WMF moved this task from To Be Triaged to Backend on the Developer-Wishlist (2017) board.Jan 18 2017, 4:07 PM

Addshore awarded a token.Jan 27 2017, 2:00 PM

cicalese subscribed.Jan 31 2017, 3:43 PM

Aklapper added a project: MediaWiki-Debug-Logger.Jan 31 2017, 8:48 PM

This proposal is selected for the Developer-Wishlist voting round and will be added to a MediaWiki page very soon. To the subscribers, or proposer of this task: please help modify the task description: add a brief summary (10-12 lines) of the problem that this proposal raises, topics discussed in the comments, and a proposed solution (if there is any yet). Remember to add a header with a title "Description," to your content. Please do so before February 5th, 12:00 pm UTC.

Tgr mentioned this in T157756: Provide a way to use log events as metrics in MediaWiki core.Feb 10 2017, 12:41 AM

Krinkle mentioned this in T167942: Database::upsert() for Postgres triggers an (ignored) error, by design.Jul 29 2017, 4:31 AM

Seb35 mentioned this in T196906: Sensible default parameters for Monolog logging.Jun 11 2018, 2:22 PM

Tgr mentioned this in T193472: Log suppressed errors with level=DEBUG.Dec 9 2018, 6:24 PM

Tgr mentioned this in T258755: Add rule against use unsafe use of Exception::getTraceAsString().Sep 17 2021, 5:47 AM

Tgr mentioned this in T142313: Add global information to debug logger context.Oct 10 2024, 2:37 PM