Correctly install xdebug on cPanel

There is a lot of conflicting and incomplete information about this around so let me write how to correctly install xdebug on a cPanel system.

First we need to actually install the xdebug php extension. This will of course not work with yum because cPanel replaces the distro php with it's own source-compiled one. So we'll need to install it through cPanel. Go to WHM -> Software -> Module Installers -> PHP Pecl -> Manage. In the search box type "xdebug", for me it currently shows version 2.2.3. Click install. It looks that it actually configures php.ini correctly and if you verify it with phpinfo(), then it actually works.

But in reality it doesn't work properly. You'll get the following messages in the error_log:

PHP Warning:  Xdebug MUST be loaded as a Zend extension in Unknown on line 0

This is annoying and fills up the logs fast. So go to WHM -> Service Configuration -> PHP Configuration Editor -> Advanced Mode. Look for "extension", you'll find that the value is "xdebug.so", delete it.

The above will take care of the warning in the error_log, but xdebug will stop working. For it to work again look for "zend_extension", you'll see "xdebug.so" as a value there, so everything looks fine. But the trick is, that you need to use the full path here. You can find it on the install screen, for me it is /usr/local/lib/php/extensions/no-debug-non-zts-20100525/xdebug.so. Save the configuration and voila, xdebug works and there is no warning in the error_log.

PS: If you know how to do these from the command line, I'd appreciate it.