implement Jinja filter to calculate the parent domain of a domain

gvaweb/webtasks/tasks.py

@@ -27,6 +27,13 @@ INSTALL_CMD = '/usr/bin/install'
 JINJAENV = Environment(loader=PackageLoader('webtasks', 'templates'))
 
 
+def _jinja_parentdomain(domain):
+    return '.'.join(domain.split('.')[1:])
+
+
+JINJAENV.filters['parentdomain'] = _jinja_parentdomain
+
+
 def _build_vhost_config_path(sitename):
     return os.path.join(settings.GVAWEB_NGINX_SITES_AVAILABLE, sitename)