I installed php-apache.
I could not see a thing so I checked the files:
pacman -Ql php-apache
php-apache /etc/
php-apache /etc/httpd/
php-apache /etc/httpd/conf/
php-apache /etc/httpd/conf/extra/
php-apache /etc/httpd/conf/extra/php_module.conf
php-apache /usr/
php-apache /usr/lib/
php-apache /usr/lib/httpd/
php-apache /usr/lib/httpd/modules/
php-apache /usr/lib/httpd/modules/libphp.so
I added to `/etc/httpd/conf/httpd.conf`:
Include conf/extra/php_module.conf
LoadModule php_module /usr/lib/httpd/modules/libphp.so
Apache service does not start anymore:
Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe. You need to recompile PHP.