PHP-FPM

PHP Versions

Centmin Mod compiles PHP from source and supports the following versions (configurable via Menu 5):

PHP Extensions

Centmin Mod includes the following PECL and built-in extensions:

How to Install PHP Extensions in Centmin Mod

Beyond the built-in extensions listed above, you can install PHP extensions in Centmin Mod using several methods: (1) install PECL extensions directly, (2) compile from source using phpize, or (3) rebuild PHP via menu option 5 with PHP_EXTRAOPTS. Some extensions also have dedicated addon scripts (e.g., addons/php72-mcrypt.sh for mcrypt, addons/ioncube.sh for IonCube).

Method 1: PECL Extensions

Install PECL extensions directly, then create a .ini file in /etc/centminmod/php.d/ to load it:

pecl install extension-name
echo "extension=extension-name.so" > /etc/centminmod/php.d/extension-name.ini
service php-fpm restart

Method 2: Compile from Source (phpize)

For extensions not in PECL, compile from source using phpize:

cd /path/to/extension-source
phpize
./configure
make
make install
echo "extension=extension-name.so" > /etc/centminmod/php.d/extension-name.ini
service php-fpm restart

Method 3: PHP Configure Flags (Menu 5 Rebuild)

To add built-in PHP extensions that require compile-time flags, set PHP_EXTRAOPTS in /etc/centminmod/custom_config.inc before running centmin.sh menu option 5 to rebuild PHP:

# Add custom PHP configure flags in /etc/centminmod/custom_config.inc
PHP_EXTRAOPTS='--enable-extension-name'

# Then rebuild PHP via menu option 5
centmin

Verify loaded PHP extensions with:

php -m

cd /svr-setup
pecl download apcu
tar xzf apcu-*.tgz
cd apcu-*/
phpize
./configure --with-php-config=/usr/local/bin/php-config
make -j$(nproc)
make install

extension=apcu.so
apc.enabled=1
apc.shm_size=32M
apc.ttl=7200
apc.enable_cli=0

fpmrestart
php --ri apcu

php.ini Customization

PHP configuration files are located at:

• /usr/local/lib/php.ini — Main php.ini
• /etc/centminmod/php.d/ — Additional .ini files (scan directory)
• /usr/local/etc/php-fpm.conf — PHP-FPM main config
• /usr/local/etc/php-fpm.d/www.conf — Default PHP-FPM pool configuration (main/default pool)
• /usr/local/nginx/conf/phpfpmd/ — Optional additional PHP-FPM pool configuration files (numbered pools, not enabled by default)

Where Is the PHP-FPM Pool Configuration File?

In Centmin Mod, the default PHP-FPM pool configuration file is at /usr/local/etc/php-fpm.d/www.conf — this is NOT the standard OS path /etc/php-fpm.d/www.conf. All vhosts share a single default [www] pool (listening on port 9000) via the php.conf include. Optional numbered pools (pool2–pool5) are available at /usr/local/nginx/conf/phpfpmd/ but are disabled by default.

PHP-FPM Pool Configuration

By default, all Nginx vhosts share a single PHP-FPM pool — the [www] pool defined in /usr/local/etc/php-fpm.d/www.conf, listening on 127.0.0.1:9000. Each vhost includes /usr/local/nginx/conf/php.conf which routes PHP requests to this shared default pool. Key tuning directives include pm.max_children (maximum worker processes, default 30), the process manager mode (pm = ondemand by default), and pm.min_spare_servers/pm.max_spare_servers for dynamic mode.

• Default pool config: /usr/local/etc/php-fpm.d/www.conf — shared by all vhosts via php.conf include
• Optional additional pools: /usr/local/nginx/conf/phpfpmd/ contains template files for numbered pools (phpfpm_pool2.conf on port 9002, phpfpm_pool3.conf on port 9003, etc.) and Unix domain socket variants
• Enabling additional pools: Uncomment include=/usr/local/nginx/conf/phpfpmd/*.conf in /usr/local/etc/php-fpm.conf, then change the vhost’s include php.conf to include php-pool2.conf (etc.)

To tune the default PHP-FPM pool settings (pm.max_children, pm.start_servers, etc.), edit /usr/local/etc/php-fpm.d/www.conf and restart PHP-FPM with service php-fpm restart.

PHP-FPM Process Manager Modes and pm.max_children

Centmin Mod's default PHP-FPM process manager mode is ondemand (set as pm = ondemand in /usr/local/etc/php-fpm.d/www.conf). Three process manager modes are available — ondemand (default), dynamic, and static. All three modes use the pm.max_children directive to set the maximum number of PHP-FPM worker processes (default: pm.max_children = 30). The key difference is how each mode manages workers relative to pm.max_children:

• pm = ondemand — Default mode. Spawns workers on demand up to pm.max_children, best for low-memory VPS.
• pm = dynamic — Scales workers between pm.min_spare_servers and pm.max_children based on demand, general-purpose.
• pm = static — Fixed pm.max_children workers always running, best for high-traffic dedicated servers.

The pm.max_children setting controls the maximum number of PHP-FPM worker processes. Calculate it as: (Available RAM − RAM for MySQL/Nginx/OS) ÷ average worker memory. Centmin Mod defaults to pm.max_children = 30. See the PHP-FPM Optimization & Tuning section for detailed sizing guidance.

Per Nginx Vhost PHP.ini Settings

By default, all Nginx vhosts share the same PHP-FPM pool and PHP settings. To configure per-site PHP settings (such as different upload_max_filesize or memory_limit values for each domain), you can enable separate PHP-FPM pools and use php_admin_value directives in each pool configuration.

Step 1: Enable Additional PHP-FPM Pools

Uncomment the pool include line in /usr/local/etc/php-fpm.conf:

# In /usr/local/etc/php-fpm.conf, uncomment this line:
include=/usr/local/nginx/conf/phpfpmd/*.conf

Step 2: Use a Pre-Existing Pool Configuration

Centmin Mod provides pre-existing pool template configs at /usr/local/nginx/conf/phpfpmd/. For example, phpfpm_pool5.conf listens on port 9005. Add php_admin_value directives to the pool config for per-site PHP settings:

[pool5]
listen = 127.0.0.1:9005
; ... existing pool settings ...

; Per-site PHP settings
php_admin_value[upload_max_filesize] = 50M
php_admin_value[post_max_size] = 55M
php_admin_value[memory_limit] = 256M
php_admin_value[max_execution_time] = 120

Step 3: Create a Custom Nginx Vhost Include

Create a custom Nginx vhost include file phpcustom-yourdomain.conf that references the pool port (e.g., 127.0.0.1:9005 instead of the default 127.0.0.1:9000):

# Custom PHP include pointing to pool5 on port 9005
fastcgi_pass 127.0.0.1:9005;

Then update your Nginx vhost config for that domain to include phpcustom-yourdomain.conf instead of the default php.conf. Restart both PHP-FPM and Nginx:

fpmrestart
ngrestart

For more details, see the forum discussion.

PHP-FPM Security

Centmin Mod applies security hardening to PHP-FPM by default:

• PHP-FPM runs as the nginx user with limited permissions
• expose_php = Off to hide PHP version headers
• disable_functions restricts dangerous functions
• Separate PHP-FPM pools can isolate users/sites

open_basedir Restrictions

The open_basedir directive restricts which directories PHP scripts can access. It can be set per-vhost in the Nginx configuration:

PHP Upgrade / Downgrade (Menu 5)

Use centmin.sh menu option 5 to upgrade or downgrade PHP on existing Centmin Mod installs. Supported PHP versions: PHP 7.4, 8.0, 8.1, 8.2, 8.3 on 132.00stable/140.00beta01; PHP 7.4, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5 on 141.00beta01. This recompiles PHP from source with all extensions.

PHP Profile-Guided Optimization (PGO) compiles are supported for PHP 7.4+ with GCC to improve PHP-FPM performance by 5-15%.

PHP-FPM Status Page

The PHP-FPM status page is available at /phpstatus and is restricted by IP whitelist in /usr/local/nginx/conf/phpstatus.conf. By default, only 127.0.0.1 is allowed.

To view from within SSH, use lynx or curl. To view from a browser, add your IP to the phpstatus.conf allow list.

Status Fields Explained

Security Backports for EOL PHP Versions

Centmin Mod actively backports CVE security patches to end-of-life PHP versions via inc/php_patch.inc. These patches are applied automatically during PHP (re)installs and upgrades via Menu 5, reducing exposure even on versions that no longer receive upstream security releases.