Maintenance mode in NGINX - the quick hack. Turn on/off by placing HTML file in relevant folder

gistfile1.nginxconf

  # Variable used for multiple IF hack
  set $is_maintenance "";
  
  # Check for notice HTML file
  if (-f /var/www/django/kontrafon/templates/maintenance.html) {
    set $is_maintenance M;
  }
  
  # Use this to circumvent maintenance message
  if ($remote_addr != "1.2.3.4") {
    set $is_maintenance "${is_maintenance}IP";
  }
  
  # Only if file is there and remote addr is not us
  if ($is_maintenance = MIP) {
    return 503;
  }
  
  error_page 503 @maintenance;
  location @maintenance {
    root /path/to/templates/;
    rewrite ^(.*)$ /maintenance.html break;
  }