cloud-apache-container/scripts/detect-memory.sh

#!/usr/bin/env bash
# detect-memory.sh — Detect container memory and calculate tuning parameters.
# Must be sourced (not executed) so variables are available to the caller.

# --- Memory detection (cgroups v2 → v1 → /proc/meminfo → fallback) ---
CONTAINER_MEMORY_BYTES=""

# cgroups v2
if [ -f /sys/fs/cgroup/memory.max ]; then
  val=$(cat /sys/fs/cgroup/memory.max 2>/dev/null)
  if [ "$val" != "max" ] && [ -n "$val" ]; then
    CONTAINER_MEMORY_BYTES=$val
  fi
fi

# cgroups v1
if [ -z "$CONTAINER_MEMORY_BYTES" ] && [ -f /sys/fs/cgroup/memory/memory.limit_in_bytes ]; then
  val=$(cat /sys/fs/cgroup/memory/memory.limit_in_bytes 2>/dev/null)
  # Values near page-aligned max (like 9223372036854771712) mean "no limit"
  if [ -n "$val" ] && [ "$val" -lt 8589934592000 ] 2>/dev/null; then
    CONTAINER_MEMORY_BYTES=$val
  fi
fi

# /proc/meminfo (host memory — used when no cgroup limit is set)
if [ -z "$CONTAINER_MEMORY_BYTES" ] && [ -f /proc/meminfo ]; then
  mem_kb=$(awk '/^MemTotal:/ {print $2}' /proc/meminfo)
  if [ -n "$mem_kb" ]; then
    CONTAINER_MEMORY_BYTES=$((mem_kb * 1024))
  fi
fi

# Fallback
if [ -z "$CONTAINER_MEMORY_BYTES" ]; then
  CONTAINER_MEMORY_BYTES=$((512 * 1024 * 1024))
fi

CONTAINER_MEMORY_MB=$((CONTAINER_MEMORY_BYTES / 1024 / 1024))

# --- Budget calculation ---
CONTAINER_ROLE=${CONTAINER_ROLE:-combined}  # combined | fpm_only | httpd_only

OS_RESERVE_MB=50
FIXED_PROCESS_MB=50
DEV_OVERHEAD_MB=0
if [ "$environment" = "DEV" ]; then
  DEV_OVERHEAD_MB=125
fi

AVAILABLE_MB=$((CONTAINER_MEMORY_MB - OS_RESERVE_MB - FIXED_PROCESS_MB - DEV_OVERHEAD_MB))
if [ "$AVAILABLE_MB" -lt 60 ]; then
  AVAILABLE_MB=60
fi

case "$CONTAINER_ROLE" in
  fpm_only)
    PHP_BUDGET_MB=$AVAILABLE_MB
    APACHE_BUDGET_MB=0
    ;;
  httpd_only)
    PHP_BUDGET_MB=0
    APACHE_BUDGET_MB=$AVAILABLE_MB
    ;;
  *)
    PHP_BUDGET_MB=$((AVAILABLE_MB * 80 / 100))
    APACHE_BUDGET_MB=$((AVAILABLE_MB * 20 / 100))
    ;;
esac

# --- PHP-FPM parameters (skipped for httpd_only) ---
if [ "$CONTAINER_ROLE" != "httpd_only" ]; then
  # PHP_WORKER_ESTIMATE_MB sizes the divisor for pm.max_children. The
  # previous default of 60 was optimistic for modern Woo/Elementor stacks:
  # the alphaone 2026-06-01 incident measured ~193 MB resident per worker
  # against the 60 MB assumption, and 15 calculated children put peak
  # demand (15 * 193 = 2.9 GB) over the 1-2 GiB container cap. 128 lands
  # closer to plugin-heavy WP reality while remaining conservative for
  # leaner sites. Customers can still override via the FPM_MAX_CHILDREN
  # env var on the container if a different shape is justified.
  PHP_WORKER_ESTIMATE_MB=${PHP_WORKER_ESTIMATE_MB:-128}

  calc_max_children=$((PHP_BUDGET_MB / PHP_WORKER_ESTIMATE_MB))
  # Floor at 2, cap at 50
  if [ "$calc_max_children" -lt 2 ]; then
    calc_max_children=2
  fi
  if [ "$calc_max_children" -gt 50 ]; then
    calc_max_children=50
  fi

  PHP_FPM_PM=${FPM_PM:-ondemand}
  PHP_FPM_MAX_CHILDREN=${FPM_MAX_CHILDREN:-$calc_max_children}
  PHP_FPM_PROCESS_IDLE_TIMEOUT=${FPM_PROCESS_IDLE_TIMEOUT:-5s}
  PHP_FPM_MAX_REQUESTS=${FPM_MAX_REQUESTS:-200}

  # Dynamic mode fallbacks (used if user overrides FPM_PM=dynamic)
  PHP_FPM_START_SERVERS=${FPM_START_SERVERS:-2}
  PHP_FPM_MIN_SPARE=${FPM_MIN_SPARE_SERVERS:-1}
  PHP_FPM_MAX_SPARE=${FPM_MAX_SPARE_SERVERS:-3}
fi

# --- Apache MPM parameters (skipped for fpm_only) ---
if [ "$CONTAINER_ROLE" != "fpm_only" ]; then
  # ServerLimit: roughly 1 process per ~25 workers, floor 2, cap 16
  calc_server_limit=$((APACHE_BUDGET_MB / 30))
  if [ "$calc_server_limit" -lt 2 ]; then
    calc_server_limit=2
  fi
  if [ "$calc_server_limit" -gt 16 ]; then
    calc_server_limit=16
  fi

  # MaxRequestWorkers: ServerLimit * ThreadsPerChild (25)
  calc_max_request_workers=$((calc_server_limit * 25))
  if [ "$calc_max_request_workers" -gt 400 ]; then
    calc_max_request_workers=400
  fi

  # StartServers: 1 for ≤1GB, 2 for larger
  calc_start_servers=1
  if [ "$CONTAINER_MEMORY_MB" -gt 1024 ]; then
    calc_start_servers=2
  fi

  APACHE_START_SERVERS=${APACHE_START_SERVERS:-$calc_start_servers}
  APACHE_SERVER_LIMIT=${APACHE_SERVER_LIMIT:-$calc_server_limit}
  APACHE_MAX_REQUEST_WORKERS=${APACHE_MAX_REQUEST_WORKERS:-$calc_max_request_workers}
  APACHE_MIN_SPARE_THREADS=${APACHE_MIN_SPARE_THREADS:-5}
  APACHE_MAX_SPARE_THREADS=${APACHE_MAX_SPARE_THREADS:-15}
  APACHE_MAX_CONNECTIONS_PER_CHILD=${APACHE_MAX_CONNECTIONS_PER_CHILD:-3000}
fi

# --- Export all variables ---
export CONTAINER_ROLE CONTAINER_MEMORY_MB
if [ "$CONTAINER_ROLE" != "httpd_only" ]; then
  export PHP_FPM_PM PHP_FPM_MAX_CHILDREN PHP_FPM_PROCESS_IDLE_TIMEOUT PHP_FPM_MAX_REQUESTS
  export PHP_FPM_START_SERVERS PHP_FPM_MIN_SPARE PHP_FPM_MAX_SPARE
fi
if [ "$CONTAINER_ROLE" != "fpm_only" ]; then
  export APACHE_START_SERVERS APACHE_SERVER_LIMIT APACHE_MAX_REQUEST_WORKERS
  export APACHE_MIN_SPARE_THREADS APACHE_MAX_SPARE_THREADS APACHE_MAX_CONNECTIONS_PER_CHILD
fi