Manual:How to debug/fr

Cette page donne une introduction de base au logiciel débogage de MediaWiki.

Une des premières choses que vous remarquerez est que "echo" ne fonctionne généralement pas ; Cela fait partie de la conception générale.

Erreurs PHP
Pour voir les erreurs PHP, ajoutez ceci au bas de :

Ou mettez-le dans :

Ou déclarer dans .htaccess:

Cela entraînera l'affichage des erreurs PHP sur la page. Cela pourrait aider les attaquants pour trouver un chemin dans votre serveur, alors désactivez-le à nouveau lorsque vous avez trouvé le problème.

Notez que des erreurs fatales PHP peuvent se produire avant que les lignes ci-dessus ne se soient exécutées, ou peuvent empêcher leur affichage. Les erreurs fatales de PHP sont généralement enregistrées dans le journal des erreurs d'Apache - vérifiez le paramètre  dans   (ou utilisez  )

Il existe plusieurs options de configuration pour faciliter le débogage. Celles qui suivent sont toutes par défaut. Activez-les en les mettant à  dans votre :
 * Activer plus de détails (comme une trace de pile) à afficher sur la page "Erreur fatale".
 * Affiche une barre d'outils sur la page avec le profilage, les messages de journal et plus encore.
 * Ajoute la partie "log messages" de wgDebugToolbar comme une liste brute à la page.
 * MediaWiki lancera des avis pour certaines conditions d'erreur possible et pour les fonctions obsolètes.

Turning display_startup_errors on
Some providers turn  off, which hides the errors even if you raise the   level. Turning it on within the program is too late! Instead you'll have to create a wrapper file around your file. In the case of MediaWiki you can just add this on top of mediawiki/index.php:

In other environments:

SQL errors
To display SQL errors in error messages instead of "(SQL query hidden)", add the following to :

You can also enable backtrace on SQL error by setting :

Zend
If you are using the Zend PHP interpreter, you can debug your code with XDebug. MediaWiki-Vagrant has built in settings for this. If you're not using MediaWiki-Vagrant, but your setup is similar, you can reuse those values. In some cases (e.g. due to a firewall), you may have to use the IDE on the same machine as the web server. In this case, you can simply set:

If you use this configuration, you may run into an issue if HHVM is also listening on the machine. Both XDebug and HHVM use port 9000 by default. However, you can change this for XDebug (and many clients). For the XDebug side, use:

Remember if you change it for XDebug, you must also change it for your IDE.

See the XDebug documentation for more information.

To debug a command-line script (e.g. PHPUnit, or a maintenance script) on MediaWiki-Vagrant, use:

Adjust the script, parameters, and remote host (it should be the IP of the computer where your IP is, 10.0.2.2 should work for MediaWiki-Vagrant) as needed. You may not need the sudo, depending on the script

HHVM
If you are using the HHVM PHP runtime, you can debug your code with the built in CLI debugger and debug server. This debugger is vaguely similar to GDB.

In order for the cli debugger to attach to web requests the hhvm.debug.enable_debugger parameter needs to be enabled. This is enabled by default on the mediawiki-vagrant development environment.

With this enabled the process is:

$ hhvm -m debug --debug-host localhost --debug-port 8089 localhost> machine list machine list 1    vagrant's default sandbox at /vagrant/www/ 2    __builtin's default sandbox at / localhost> machine attach 2 machine attach 2 Attaching to __builtin's default sandbox at / and pre-loading, please wait... localhost> break MediaWiki::run break MediaWiki::run Breakpoint 1 set upon entering MediaWiki::run localhost> continue continue

The machine attach 2 is required. It may not always be machine 2, but it will always be the one identified as "__builtin's default sandbox at /". This is only true on configurations that pass a  over fastcgi to hhvm (such as  and wmf production), alternate configurations may vary.

At this point the next web request that enters MediaWiki::run (all of them) will break and put you on a command prompt:

Breakpoint 1 reached at MediaWiki::run on line 450 of /vagrant/mediawiki/includes/MediaWiki.php 449           try { 450*                  $this->checkMaxLag; 451                   try { localhost>

The HHVM CLI debugger has an excellent help system, for example try help break for details on the syntax of choosing break points.

Logging
For much greater detail, you need to profile and log errors.

The instructions below are only valid for the default configuration. If you change, for example enable the   role on a  box, these settings will probably be ignored.

Setting up a debug log file
To save errors and debugging information to a log, add  to the   file. Change the value to a text file where you want to save the debug trace output.

The MediaWiki software must have permissions from your operating system to create and write to this file, for example in a default Ubuntu install it runs as user & group :. Here's a sample setting:

This file will contain much debug information from MediaWiki core and extensions. Some subsystems write to custom logs, see to capture their output.

Database transaction lifecycle debugging can be enabled for some databases with.

Creating a custom log file
To create a custom log file that only holds your specific debug statements, use the  function. This function takes two arguments, the text string to log and the path to the log file:

Creating custom log groups
If you're debugging several different components, it may be useful to direct certain log groups to write to a separate file.

To set up custom log groups, use the following to LocalSettings.php:

To log to one of these groups, call  like this:

Structured logging
Structured logging allows you to include fields in your log records. See for more information.

Statistics
Advanced client-side logging can be performed with Extension:EventLogging, which requires a complex setup and careful inspection of privacy issues.

Simple counting of certain kind of events is possible (since MediaWiki 1.25) using StatsD. StatsD offers meters, gauges, counters, and timing metrics.

Usage example:

The metrics can be sent to a StatsD server, which may be specified via the  configuration variable. (If not set, the metrics are discarded.) You can work with StatsD locally (without needing a Graphite server) by starting a StatsD server and configuring it with the "backends/console" backend, which will output metrics to the console.

As of MediaWiki 1.25,  is a shortcut for the   method on the main   instance.

Send debug data to an HTML comment in the output
This may occasionally be useful when supporting a non-technical end-user. It's more secure than exposing the debug log file to the web, since the output only contains private data for the current user. But it's not ideal for development use since data is lost on fatal errors and redirects. Use on production sites is not recommended. Debug comments reveal information in page views which could potentially expose security risks.



Working live with MediaWiki objects
is an interactive script to evaluate and interact with MediaWiki objects and functions in a fully initialized environment.

$ php maintenance/eval.php > print wfMessage("Recentchanges")->plain; Recent changes

The portable virtual machine integrates the interactive PHP shell   (when using the default HHVM) or   (when using Zend).

Callable updates
Code embedded in the DeferredUpdates::addCallableUpdate function, such as $rc->save in RecentChange.php, is not executed during the web request, so no error message will be displayed if it fails. For debugging, it may be helpful to temporarily remove the code from within the function so that it is executed live.

Client side debugging
Wikipedia offers a rich set of tools for debugging client side JavaScript. In addition to the MediaWiki tools, other techniques are available to assist with diagnosing client interactions.

Tools:


 * ResourceLoader offers a means to ensure JavaScript is easily viewable by client-side tools.
 * ResourceLoader also provides a safety oriented way to log to the client console. Beyond the native JavaScript logging function, it provides a check to ensure that a console is available and that logging does not produce its own error. ResourceLoader/Features also describes this feature.
 * Browser tools may provide native functionality to debug client side script.
 * Network tracers, like Wireshark can provide insight into the script that is being provided by a page.

Voir aussi

 * Manual:Profiling
 * ResourceLoader: ResourceLoader/Developing with ResourceLoader
 * All configuration variables related to debugging/logging: Manual:Configuration settings#Debug/logging
 * Useful debugging tip:  (dies with the given message and prints the callstack)
 * Manual:Errors and Symptoms
 * wikitech:Debugging - debugging on Wikimedia's production cluster
 * wikitech:Debugging - debugging on Wikimedia's production cluster