Hi Siggi
I think the pool is configured in here: /etc/php5/fpm/pool.d/$yourdomain.com.conf. The problem is that this file is rewritten when the customer changes mentioned setting. Check here: /etc/imscp/php-fpm/working. The file there is adjusted and then copied to the php5/fpm path. So if you adjust the template file, it will be reused. But the template could be recreated during imscp panel updates.
For Apache2 there is /etc/apache2/imscp where you can put custom config stuff for each domain. Edits here will only work with mod_php. Probably such an include could make sense for php-fpm as well?
Simple solution
1. Edit the /etc/php5/fpm/php-fpm.conf and at bottom, add the following:
2. Create the /etc/php5/fpm/imscp_custom.conf file
Then from now, to add or override PHP configuration parameter for a specific pool, just add in the /etc/php5/fpm/imscp_custom.conf file something like
It's just an idea. I'll test it. This allow you to create only one file for custom PHP snippets.
Re;
The solution above only works for parameters which are not yet defined in the pool configuration file. Already defined parameters are not overridden.
To resume if in the /etc/php5/fpm/pool.d/domain1.tld.conf file you already have:
Adding the following in the /etc/php5/fpm/imscp_custom.conf file
Will not work (i.e. usage of phpinfo() function will be still disallowed).
Re;
The solution above only works for parameters which are not yet defined in the pool configuration file. Already defined parameters are not overridden.
Any chance to do that?
I'll implement that.
We can override any of the values as long they are defined first with php_value insteand of php_admin_value. I'll so provide custom file with predefined values but custom file, once installed will not be overriden 
Could this be possible like what we have for Apache? A imscp directory with one include file per domain/pool?
Another question comes to mind: what sense has php_admin_value? If it's there to not be overwritten, assigning it as php_value also means it can be overwritten by customer php's? That would mean a security threat then...
I will check PHP docs
Hello ;
Any parameter set with php_admin_value cannot be overridden using the ini_set() function while any parameter set with php_value can This is so difficult provide default restricted values ( set with php_admin_value ) in pool configuration files because we cannot overridden them in local pool configuration file. As I see, we must provide local local pool configuration file for each pool which come with restricted parameters ( set with php_admin_value). After, if the admin decide to change them, it's not our problem. Once installed, the local pool configuration file must not be overridden by the i-mscp installer.
