gistfile1.txt

server {
  location / {

    if (-f $document_root/system/maintenance.html) {
      return 503;
    }

    try_files $uri $uri/index.html @proxy;
  }

  error_page 503          @503;
  location @503 {
    # Serve static assets if found when in maintenance mode.
    if (-f $request_filename) {
      break;
    }

    # Serve the maintenance page if we're in maintenance mode.
    if (-f $document_root/system/maintenance.html) {
      rewrite ^(.*)$ /system/maintenance.html break;
    }

    # This is a normal 503 so serve that page.
    rewrite ^(.*)$ /503.html break;
  }
}

$document_root is empty if there's no root in the server { } level.

• kblessinggr from #nginx/freenode