PHP Integration

Nginx does not execute PHP natively. It hands PHP requests to PHP-FPM (FastCGI Process Manager) via a FastCGI socket. This module covers the complete connection from Nginx location block to PHP-FPM worker process.

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How It Works

Nginx receives .php request
  └── fastcgi_pass → PHP-FPM pool (via UNIX socket or TCP)
       └── PHP-FPM worker forks/spawns
            └── Executes the PHP script
                 └── Returns response to Nginx
                      └── Nginx sends to client

Using a UNIX socket instead of TCP is faster because it avoids the TCP stack entirely — prefer it unless PHP-FPM is on a different host.

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What You Will Learn

• How to install PHP-FPM and connect it to Nginx
• What fastcgi_params and fastcgi.conf do
• How to configure PHP-FPM pools (pm modes, worker counts)
• How to tune php.ini for production
• How to run PHP 8.1, 8.2, and 8.4 simultaneously for different sites
• How to enable and verify OPcache

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Topics in This Module

• PHP-FPM Installation — Install, enable, and verify PHP-FPM on Debian and RHEL
• Connecting Nginx to PHP-FPM — fastcgi_pass, socket vs TCP, fastcgi_params snippet
• PHP-FPM Pool Configuration — pm modes (static/dynamic/ondemand), worker limits, socket path
• php.ini Tuning — Memory, execution time, upload limits, error logging
• OPcache Configuration — Enable, memory sizing, JIT, preload
• Multiple PHP Versions — Run PHP 8.1 + 8.4 simultaneously, per-site version assignment

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Best Practices

• Always use a UNIX socket for PHP-FPM (/run/php/phpX.X-fpm.sock) on single-server setups
• Set pm = dynamic for variable-load production sites
• Enable OPcache — it is the single largest PHP performance improvement
• Set opcache.revalidate_freq = 0 in production (never check disk for changes)
• Use separate PHP-FPM pools per site for isolation and resource control

Success Checkpoint

By the end of this module you should be able to install PHP-FPM, write a working fastcgi_pass location block, configure a pool, and verify PHP is executing correctly.