Early Hints support

An alternative to PUSHing resources is to send Link headers to the client before the response is even ready. This uses the HTTP feature called Early Hints and is described in RFC 8297.

You can configure this by using an ApacheConfigFilter, and the apache directives H2EarlyHints and H2PushResource:

   <filter>
        <filter-name>H2EarlyHintsFilter</filter-name>
        <filter-class>ch:nevis:navajo:apglue:httpd_2_4_x:servlet:ApacheConfigFilter</filter-class>
        <init-param>
            <param-name>ServerConfig</param-name>
            <param-value>
            H2EarlyHints on
            </param-value>
        </init-param>
        <init-param>
            <param-name>LocationConfig</param-name>
            <param-value>
            H2PushResource /path/as/seen/by/the/frontend/style.css
            </param-value>
        </init-param>
    </filter>

The configured H2PushResource path has to be the same as the one called by the frontend.

For more information about Early Hints, see the apache reference guide.