I'm using Google Cloud ESP endpoint, and I want the ESP proxy to forward the clients IPs to the backend service for analytics purposes. From the Google docs I found that I should use --add_request_header to add headers to the request, and from the envoy docs (ESP is based on envoy proxy) they say the remote client IP is in the variable x-envoy-external-address, so I want to know how combine all things together and pass the clients IPs to the backend service in the args section upon ESP startup?

Another thing, how to force HTTPS traffic only by the ESP? and will that redirect HTTP requests (clients) automatically to HTTPS?