When writing Dockerfiles for PHP and MySQL, it's important to focus on security, efficiency, and maintainability. Here are some best practices specific to Dockerfiles for PHP and MySQL environments:

1. Use Official Base Images

• Why: Official Docker images for PHP and MySQL are regularly updated and optimized for performance and security. Always use these as your base.

• Example:
  

   FROM php:7.4-fpm
   FROM mysql:8.0
  

2. Minimize PHP Extensions and Packages

• Why: Install only the necessary PHP extensions and Linux packages to keep your image lightweight and reduce potential security vulnerabilities.

• Example:
  

   RUN apt-get update && apt-get install -y \
       libpng-dev \
       libjpeg-dev \
       libfreetype6-dev \
   && docker-php-ext-configure gd --with-freetype --with-jpeg \
   && docker-php-ext-install gd
  

3. Optimize PHP Configuration

• Why: Customize your PHP configuration to suit your application’s needs. Use environment variables or copy custom php.ini files to configure settings like memory limits, error reporting, and upload sizes.

• Example:
  

   COPY php.ini /usr/local/etc/php/
  

4. Leverage Multi-Stage Builds for PHP

• Why: Use multi-stage builds to separate the build environment (e.g., compiling PHP extensions) from the final runtime environment. This keeps the final image lean and secure.

• Example:
  

   FROM php:7.4-fpm AS builder
   WORKDIR /usr/src/php/ext
   RUN docker-php-ext-install pdo_mysql
  
   FROM php:7.4-fpm
   COPY --from=builder /usr/local/lib/php/extensions/no-debug-non-zts-20190902/pdo_mysql.so /usr/local/lib/php/extensions/no-debug-non-zts-20190902/
   RUN docker-php-ext-enable pdo_mysql
  

5. Configure MySQL for Production

• Why: Use environment variables to configure MySQL in a way that’s optimized for production. Avoid hardcoding credentials and use Docker secrets or environment variables instead.

• Example:
  

   ENV MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
   ENV MYSQL_DATABASE=mydatabase
   ENV MYSQL_USER=myuser
   ENV MYSQL_PASSWORD=${MYSQL_PASSWORD}
  

6. Persist MySQL Data Using Volumes

• Why: To avoid data loss, persist MySQL data outside the container using Docker volumes. This ensures your data is safe even if the container is removed.

• Example:
  

   version: '3.8'
   services:
     db:
       image: mysql:8.0
       volumes:
         - db_data:/var/lib/mysql
       environment:
         MYSQL_ROOT_PASSWORD: example
         MYSQL_DATABASE: exampledb
  
   volumes:
     db_data:
  

7. Use .dockerignore for PHP Projects

• Why: Exclude unnecessary files and directories (e.g., node_modules, .git, tests, etc.) from being copied into the Docker image, reducing the build context and resulting image size.

• Example:
  

   .git
   node_modules
   tests
   .env
  

8. Keep the Image Lean

• Why: Remove unnecessary dependencies and temporary files after installation to minimize the image size.

• Example:
  

   RUN apt-get update && apt-get install -y \
       libzip-dev \
   && docker-php-ext-install zip \
   && apt-get clean \
   && rm -rf /var/lib/apt/lists/*
  

9. Use Supervisord for Managing Multiple Processes

• Why: If your PHP container needs to run multiple services (e.g., PHP-FPM and a cron job), use supervisord to manage them efficiently.

• Example:
  

   RUN apt-get update && apt-get install -y supervisor
   COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
   CMD ["supervisord", "-c", "/etc/supervisor/conf.d/supervisord.conf"]
  

10. Enable OPCache for PHP

• Why: Enabling OPCache improves PHP performance by caching the compiled bytecode of PHP scripts, reducing the need for PHP to recompile the scripts on each request.

• Example:
  

   RUN docker-php-ext-install opcache
   COPY opcache.ini /usr/local/etc/php/conf.d/opcache.ini
  

11. Separate Application Code and Configuration

• Why: Keep your application code and configuration files (like php.ini or my.cnf) separate to allow easy updates and better management.

• Example:
  

   COPY src/ /var/www/html/
   COPY php.ini /usr/local/etc/php/
  

12. Health Checks

• Why: Use Docker's health check functionality to monitor the health of your PHP and MySQL containers, ensuring they are running correctly.

• Example:
  

   HEALTHCHECK --interval=30s --timeout=10s --retries=3 \
     CMD curl -f http://localhost/health || exit 1
  

Conclusion

By following these best practices, you can create Dockerfiles that produce efficient, secure, and maintainable containers for your PHP and MySQL projects. This will result in a smoother development process and more stable production environments.