What does and how exactly ENABLE_TUNING_FPM works

[FluffyDiscord]

I didn't find anything in the docs, except that it somehow automatically adjust fpm settings. Can someone explain what it checks, and how it figured out the settings that it adjusts?

[shinsenter]

@FluffyDiscord
I think you can check the code here.

php/src/php/common/rootfs/etc/hooks/bootstrap/00-php-config

Lines 22 to 59 in d87eddf

	if has-cmd php-fpm && is-true "$ENABLE_TUNING_FPM"; then
	debug-echo -i "Tune PHP-FPM performance."
	config_file="$(php-envvars fpm_conf)"
	mkdir -p "$(dirname "$config_file")"
	touch "$config_file"
	sed -i '/^; Tuning PM/,$d' "$config_file" 2>/dev/null || true
	# gather system info
	cpu_cores=$(grep -c ^processor /proc/cpuinfo)
	ram_mb=$(free -m | awk '/^Mem:/{print $2}')
	# read scaling from env or fallback to defaults
	scale_children="${PHPFPM_SCALE_CHILDREN:-5}"
	scale_start="${PHPFPM_SCALE_START:-2}"
	scale_min_spare="${PHPFPM_SCALE_MIN_SPARE:-1}"
	scale_max_spare="${PHPFPM_SCALE_MAX_SPARE:-3}"
	max_requests="${PHPFPM_MAX_REQUESTS:-500}"
	# calculate values
	pm="dynamic"
	pm_max_children=$((cpu_cores * scale_children))
	pm_start_servers=$((cpu_cores * scale_start))
	pm_min_spare_servers=$((cpu_cores * scale_min_spare))
	pm_max_spare_servers=$((cpu_cores * scale_max_spare))
	cat <<EOF >> "$config_file"
	; Tuning PM
	[$(is-true "$ALLOW_RUNTIME_PHP_ENVVARS" && echo '${PHP_POOL_NAME}' || echo "${PHP_POOL_NAME}")]
	pm = $pm
	pm.max_children = $pm_max_children
	pm.start_servers = $pm_start_servers
	pm.min_spare_servers = $pm_min_spare_servers
	pm.max_spare_servers = $pm_max_spare_servers
	pm.max_requests = $max_requests
	; Generated at $(date "+%Y-%m-%d %H:%M:%S")
	EOF

Basically, when you set ENABLE_TUNING_FPM=1, this script runs and writes PHP-FPM config to /usr/local/etc/php-fpm.d/zz-docker-shinsenter-php.conf, and PHP-FPM will load it when the container starts.