Add shared httpd + PHP-FPM-only container architecture

Separate Apache and PHP-FPM into distinct container roles to reduce
per-customer memory overhead on shared servers. Adds three new images:
- Dockerfile.fpm: PHP-FPM only (no Apache), listens on TCP port 9000
- Dockerfile.shared-httpd: Apache only (no PHP), with SSL and proxy_fcgi
- Existing Dockerfile unchanged for standalone mode

Key changes:
- detect-memory.sh: CONTAINER_ROLE env var (combined/fpm_only/httpd_only)
  controls the memory budget split
- create-php-config.sh: FPM_LISTEN env var for TCP port vs Unix socket,
  added /fpm-ping and /fpm-status health endpoints
- New entrypoints for each container role
- tune-mpm.sh for hot-adjusting Apache MPM settings
- shared-vhost-template.tpl with proxy_fcgi and SSL on port 443
- CI/CD builds all three image types in parallel

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/detect-memory.sh

@@ -38,6 +38,8 @@ fi
 CONTAINER_MEMORY_MB=$((CONTAINER_MEMORY_BYTES / 1024 / 1024))
 
 # --- Budget calculation ---
+CONTAINER_ROLE=${CONTAINER_ROLE:-combined}  # combined | fpm_only | httpd_only
+
 OS_RESERVE_MB=50
 FIXED_PROCESS_MB=50
 DEV_OVERHEAD_MB=0
@@ -50,63 +52,83 @@ if [ "$AVAILABLE_MB" -lt 60 ]; then
   AVAILABLE_MB=60
 fi
 
-PHP_BUDGET_MB=$((AVAILABLE_MB * 80 / 100))
-APACHE_BUDGET_MB=$((AVAILABLE_MB * 20 / 100))
+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 ---
-PHP_WORKER_ESTIMATE_MB=${PHP_WORKER_ESTIMATE_MB:-60}
+# --- PHP-FPM parameters (skipped for httpd_only) ---
+if [ "$CONTAINER_ROLE" != "httpd_only" ]; then
+  PHP_WORKER_ESTIMATE_MB=${PHP_WORKER_ESTIMATE_MB:-60}
 
-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 [ "$calc_max_children" -gt 50 ]; then
-  calc_max_children=50
+  calc_max_children=$((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:-10s}
+  PHP_FPM_MAX_REQUESTS=${FPM_MAX_REQUESTS:-500}
+
+  # Dynamic mode fallbacks (used if user overrides FPM_PM=dynamic)
+  PHP_FPM_START_SERVERS=${FPM_START_SERVERS:-2}
+  PHP_FPM_MIN_SPARE=${FPM_MIN_SPARE_SERVERS:-1}
+  PHP_FPM_MAX_SPARE=${FPM_MAX_SPARE_SERVERS:-3}
 fi
 
-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:-10s}
-PHP_FPM_MAX_REQUESTS=${FPM_MAX_REQUESTS:-500}
+# --- Apache MPM parameters (skipped for fpm_only) ---
+if [ "$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
 
-# 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=${FPM_MAX_SPARE_SERVERS:-3}
+  # MaxRequestWorkers: ServerLimit * ThreadsPerChild (25)
+  calc_max_request_workers=$((calc_server_limit * 25))
+  if [ "$calc_max_request_workers" -gt 400 ]; then
+    calc_max_request_workers=400
+  fi
 
-# --- Apache MPM parameters ---
-# 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
+  # 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
-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}
 
 # --- Export all variables ---
-export CONTAINER_MEMORY_MB
-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
-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
+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