PHP Runtime Tuning on Zerops

Keywords

PHP_INI, PHP_FPM, php.ini, fpm, upload_max_filesize, post_max_size, memory_limit, max_execution_time, max_children, ondemand, dynamic, php tuning, upload limit, file upload

TL;DR

Override php.ini via PHP_INI_* env vars, FPM via PHP_FPM_*. Both require restart (not reload). Zerops defaults: upload/post = 1024M, FPM dynamic 20/2/1/3. Upload bottleneck is L7 balancer (50MB subdomain), not PHP.

PHP Configuration (PHP_INI_*)

Override any php.ini directive via PHP_INI_{directive} env vars in run.envVariables or via zerops_env API.

Requires restart to take effect. Reload writes config files (/etc/php*/conf.d/overwrite.ini) but FPM master does not re-read INI on reload.

Zerops Platform Defaults

Zerops overrides several stock PHP values for production use:

Directive	Zerops default	Stock PHP	Why
upload_max_filesize	1024M	2M	Generous upload limit (L7 balancer is the real gate)
post_max_size	1024M	8M	Matches upload limit
display_errors	off	on	Production: errors to logs, not browser
error_reporting	22527	32767	E_ALL & ~E_DEPRECATED & ~E_STRICT
log_errors	1	0	Errors go to log files
output_buffering	4096	0	Buffered output for performance
date.timezone	UTC	(empty)	Consistent timezone
sendmail_path	/usr/sbin/sendmail -t -i	(empty)	System sendmail wired

Example

zerops:
  - setup: app
    run:
      base: php-nginx@8.4
      envVariables:
        PHP_INI_upload_max_filesize: 10M
        PHP_INI_post_max_size: 12M
        PHP_INI_memory_limit: 256M
        PHP_INI_max_execution_time: 60
        PHP_INI_max_input_vars: 5000

PHP-FPM (PHP_FPM_*)

Configure FPM process management via PHP_FPM_* env vars. Requires restart — same as PHP_INI.

Config files are written to /etc/php*/php-fpm.d/www.conf by zerops-zenv at container startup.

Dynamic Mode (default)

Pre-forks a pool of workers. Good for consistent traffic.

Variable	Default
PHP_FPM_PM	dynamic
PHP_FPM_PM_MAX_CHILDREN	20
PHP_FPM_PM_START_SERVERS	2
PHP_FPM_PM_MIN_SPARE_SERVERS	1
PHP_FPM_PM_MAX_SPARE_SERVERS	3
PHP_FPM_PM_MAX_SPAWN_RATE	32
PHP_FPM_PM_MAX_REQUESTS	500

High-traffic example:

envVariables:
  PHP_FPM_PM_MAX_CHILDREN: 50
  PHP_FPM_PM_START_SERVERS: 10
  PHP_FPM_PM_MIN_SPARE_SERVERS: 5
  PHP_FPM_PM_MAX_SPARE_SERVERS: 15
  PHP_FPM_PM_MAX_REQUESTS: 1000

Ondemand Mode

Spawns workers only when requests arrive. Saves memory for low-traffic sites.

envVariables:
  PHP_FPM_PM: ondemand
  PHP_FPM_PM_MAX_CHILDREN: 20
  PHP_FPM_PM_PROCESS_IDLE_TIMEOUT: 60s
  PHP_FPM_PM_MAX_REQUESTS: 500

Available parameters for ondemand:

• PHP_FPM_PM_MAX_CHILDREN -- maximum child processes
• PHP_FPM_PM_PROCESS_IDLE_TIMEOUT -- idle timeout before termination (default: 60s)
• PHP_FPM_PM_MAX_REQUESTS -- requests per process before recycling (default: 500)

Upload Limits (3-layer chain)

File uploads pass through three layers -- ALL must allow the size:

1. L7 Balancer: client_max_body_size = 512m (custom domain) / 50MB fixed (subdomain)
2. PHP: upload_max_filesize = 1024M (Zerops default)
3. PHP: post_max_size = 1024M (Zerops default)

Zerops pre-configures generous PHP limits, so the L7 balancer is typically the bottleneck:

• Subdomain (zerops.app): hard 50MB cap, cannot be changed
• Custom domain: 512m default, configurable via custom Nginx template

Gotchas

• Reload does NOT apply changes -- PHP_INI_* and PHP_FPM_* both require restart. Zerops reload rewrites config files via zerops-zenv but does not signal FPM to re-read them.
• Upload fails at 50MB on subdomain -- this is the L7 balancer limit, not PHP. Use a custom domain for larger uploads.
• post_max_size must be >= upload_max_filesize -- PHP silently drops the POST body if it exceeds post_max_size, even if the file itself is under upload_max_filesize.