Add support for overriding PHP-FPM process manager settings

[Morik]

Hi,

I am currently using this image and would like to customize PHP-FPM process manager settings such as:

• pm
• pm.max_children
• pm.start_servers
• pm.min_spare_servers
• pm.max_spare_servers
• pm.max_requests

Is there already a supported way to override these settings that I may have overlooked?

I checked the documentation but couldn't find an obvious mechanism to configure these values through environment variables or other image-specific configuration options.

If this is not currently supported, would you be open to adding support for overriding common PHP-FPM process manager settings via environment variables?

For example:

environment:
  PHP_FPM_PM: dynamic
  PHP_FPM_PM_MAX_CHILDREN: 50
  PHP_FPM_PM_START_SERVERS: 5
  PHP_FPM_PM_MIN_SPARE_SERVERS: 5
  PHP_FPM_PM_MAX_SPARE_SERVERS: 10
  PHP_FPM_PM_MAX_REQUESTS: 500

This would make it easier to tune PHP-FPM for different workloads without maintaining custom FPM configuration files.

Thanks!