Override php-fpm pool config values with another file

Having to customize the php-fpm pool configuration of a new server, I wonder if it is possible / allowed / recommended to have a new pool file, which name goes alphabetically after the original one, which only has values that override the initial configuration.

The original configuration is in /etc/php/7.0/fpm/pool.d named www.conf.

It seems, according to the pages related to the installation, engineers modify directly the original (saving a copy of the initial values). E.g.

[www]
...
user www-data
group www-data
pm.max_children 2

gives after modification

[www]
...
user myapp         ; was www-data
group myapp        ; was www-data
pm.max_children 8  ; was 2

But it seems that could be a task to be repeated after the next upgrade of php-fpm (furthermore the configuration is in a 7.0 path, that's worrying).

Instead of modifying the original file, I would like to keep it unchanged, and add another one, say wwwmyapp.conf that would declare the same pool, and having only the values that have changed

in wwwmyapp.conf

[www]        ; same pool!
user myapp
group myapp
pm.max_children 8

in pool.d, list of files

www.conf
wwwmyapp.conf

since in php-fpm.conf all pool conf files are loaded, the values of wwwmyapp will be read after the ones of www ( in the same www pool ) and should override the first values.

• It seems to work in a few tests and no error reported, but will it work all the time, and for all values?
• Should we overwrite the config file directly instead?

Couldn't find an answer in any doc, even on php.net.

Solution 1:

Could not find an "official" confirmation from another source, but here is some outcome after doing some research:

Analyzing the source code of php7.0-fpm and more specifically fpm-conf.c, it appears that

• the main configuration file php-fpm.conf is read first [ fpm_conf_load_ini_file() ],
• all include directives are read in order, giving a list of files thanks to glob(),
• each of the file is parsed by the same fpm_conf_load_ini_file(),
• an entry in the file overwrites any previously set value,
• any new include will have a recursive call to the includes processing function, and
• the glob() function sorts names, by default (no GLOB_NOSORT option)

Thus we can assume - at least in this version but this is unlikely to change soon considering the present code - that it is safe to arrange the pool.d directory configuration files in alphabetical order ; any previously recorded value being overwritten by an entry with the same name read after.

We have a clean way to handle configuration files for php-fpm, keeping the distribution ones untouched, and adding custom files having name alphabetically greater than the packaged ones, that contain the few options that have to be changed.

Solution 2:

In case u have some file like php-overrides.ini you should copy it to

/etc/php/7.0/fpm/conf.d/99-overrides.ini

99 prefix is due to order of execution