I propose to backport mod_proxy_http2 to 2.4.x as an experimental module with the same restrictions as mod_http2.
Purpose: mod_proxy_http2 allows proxy HTTP/2 connections, using its own h2: and h2c: proxy schemes for the configuration. It expects the backend to talk HTTP/2 and will not fallback to HTTP/1.1. When called inside a HTTP/1.1 connection, it will open/reuse an existing HTTP/2 backend connection for this one request. When called inside a HTTP/2 connection, new requests can be transferred to an already ongoing backend HTTP/2 connection for the same master. So, in an ideal case, all concurrent streams inside one frontend connection are managed to the backend over a single connection as well. Status: The module functions in standard HTTP/2 test scenarios and seems stable under basic load. Performance is good for small requests but flow control handling is not good for large responses and performance degrades. Collecting feedback from early testers will be valuable - as was for mod_http2.
