Php fpm on apache

Make sure to have following flags in make.conf:

USE="fpm threads"
APACHE2_MODULES="proxy_fcgi"
APACHE2_MPMS="event"

Emerge apache / php to activate flags. In case of using redis

emerge -v1 dev-php/pecl-redis

Set user and group to apache for php-fpm in /etc/php/fpm-php7.4/fpm.d/www.conf

user = apache
group = apache

Add and start php-fpm

rc-update add php-fpm default
/etc/init.d/php-fpm start

Disable standard PHP module in apache by editing /etc/conf.d/apache2 and removing '-D PHP'

Activate php-fpm in apache via the fcgi proxy:

        ProxyPassMatch ^/(.*\.php(/.*)?)$ fcgi://127.0.0.1:9000/var/www/localhost/htdocs/$1
        DirectoryIndex index.php

Make sure to use the same path in the fcgi url to reference the path on your server (documentroot). Also put the ProxyPassMatch directive after other ProxyPass directives or otherwise the reverse proxies will no longer work for *.php links as they would be intercepted by this one.

Restart apache

To verify the apache mpm, run

apache2ctl -M | grep mpm

In this case it should return: mpm_event_module (static)

To verify the php fcgi, create a .php file containing:

<?php
        phpinfo();
?>

The output should contain: Server API FPM/FastCGI