added custom entrypoint

entrypoint.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# Generate the config.js file
+cat <<EOF > /usr/share/nginx/html/config.js
+window._env_ = {
+  REACT_APP_API_HOSTNAME: "${REACT_APP_API_HOSTNAME}"
+  REACT_APP_KC_HOSTNAME: "${REACT_APP_KC_HOSTNAME}"
+};
+EOF
+
+# Start Nginx
+nginx -g "daemon off;"