.. _config_http_filters_on_demand: On-demand VHDS Updates ====================== The on-demand VHDS filter is used to request a :ref:`virtual host ` data if it's not already present in the :ref:`Route Configuration `. The contents of the *Host* or *:authority* header is used to create the on-demand request. For an on-demand request to be created, :ref:`VHDS ` must be enabled and either *Host* or *:authority* header be present. On-demand VHDS cannot be used with SRDS at this point. Configuration ------------- * :ref:`v2 API reference ` * This filter should be configured with the name *envoy.filters.http.on_demand*. * The filter should be placed before *envoy.router* filter in the HttpConnectionManager's filter chain.