Harden Docker production build

docker-entrypoint.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+rm -f /tmp/.X99-lock
+Xvfb :99 -screen 0 1024x768x24 &
+xvfb_pid=$!
+
+export DISPLAY=:99
+
+npm start &
+app_pid=$!
+
+term_handler() {
+  kill "$app_pid" 2>/dev/null || true
+  kill "$xvfb_pid" 2>/dev/null || true
+}
+
+trap term_handler INT TERM
+
+while kill -0 "$app_pid" 2>/dev/null; do
+  if ! kill -0 "$xvfb_pid" 2>/dev/null; then
+    echo "Xvfb exited; stopping app." >&2
+    kill "$app_pid" 2>/dev/null || true
+    wait "$app_pid" 2>/dev/null || true
+    exit 1
+  fi
+  sleep 1
+done
+
+wait "$app_pid"
+app_status=$?
+kill "$xvfb_pid" 2>/dev/null || true
+wait "$xvfb_pid" 2>/dev/null || true
+exit "$app_status"