Currently, routes defined via RDS can have a RedirectAction that specify the host and path a matching Route will be redirected to. This works for the cases where one knows what the destination path is up front but not so much for the cases where prefix/suffix rewriting is needed. Nginx does this by allowing one to specify a matching regex on the original path and being able to reference capture groups in the destination:

rewrite ^/foo/(bar)/(.*)$ https://$server_name/$1/$2 permanent;

Ideally, envoy would able to support that kind of referencing but, in lieu of that, being able to at least refer to the original path in a RedirectAction.PathRedirect would help get us most of the way there. The same goes for protocol rewriting.

Context: https://envoyproxy.slack.com/archives/C78M4KW76/p1510966916000159