Dockerize PHP: FPM, OPcache, and Containers That Scale

PHP deployments traditionally depend on the host OS's PHP version, installed extensions, and php.ini settings. Every server is a snowflake - different OPcache configs, different extension versions, different FPM pool settings. When something breaks in production, you cannot reproduce it locally because your Mac runs PHP 8.3 and the server runs 8.1.

Docker pins every layer: PHP version, extensions (compiled from source if needed), OPcache settings, and FPM pool configuration. The same image runs on your laptop, in CI, and in production.

Two-container architecture with PHP-FPM and Nginx:

• PHP-FPM container: FROM php:8.3-fpm-alpine - installs extensions via docker-php-ext-install and docker-php-ext-configure (pdo_mysql, pdo_pgsql, gd, intl, opcache, redis via PECL). Custom php.ini sets opcache.enable=1, opcache.memory_consumption=256, opcache.max_accelerated_files=20000. FPM pool configured with pm=dynamic, tuned worker counts.
• Nginx container: FROM nginx:1.25-alpine - custom config proxies *.php requests to the FPM container via FastCGI, serves static files directly.

Compose defines both services on a shared network, with Nginx depending on FPM. Health check uses php-fpm-healthcheck script or fcgi ping. Volumes mount uploads directory for persistent storage.

• PHP-FPM + Nginx two-container docker-compose.yml
• Custom php.ini with OPcache tuning for production
• FPM pool configuration with dynamic process management
• Nginx config with FastCGI proxy, gzip, and security headers
• Extension installation script for common extensions (GD, Intl, PDO, Redis)
• Persistent volume setup for uploads and sessions