For each customer, inside CageFS, file alt_php.ini is located in /etc/cl.php.d/alt-phpXX (XX - version of PHP, like 52 or 53). The file contains PHP extension settings and extension directives selected by customer. This file exists for each customer, for each PHP version.
Note, that this is 'local' to CageFS, and different users will have different files. The file is not visible in /etc/cl.php.d outside CageFS. If you would like to view that file, use:
# cagefsctl -e USERNAME
to enter into CageFS for that user. Then type: exit; to exit from CageFS
This file has to be updated using cagefsctl --rebuild-alt-php-ini after updating alt-php RPMs
Admin can change individual settings for PHP extensions by changing that extension's ini file, like editing /opt/alt/php54/etc/php.d.all/eaccelerator.ini and then running:
to propagate the change.