Hypercorn is based on the excellent hyper-h2 library.
The recommendations in this documentation for the SSL/TLS ciphers and
version are from RFC 7540. As
required in the RFC ECDHE+AESGCM is the minimal cipher set HTTP/2
and TLSv2 the minimal TLS version servers should support. By default
Hypercorn will use this as the cipher set.
The ALPN Protocols should be set to include h2 and http/1.1 as
Hypercorn supports both. It is feasible to omit one to only serve the
other. If these aren’t set most clients will assume Hypercorn is a
HTTP/1.1 only server. By default Hypercorn will set h2 and http/1.1 as
the ALPN protocols.
Most clients, including all the web browsers only support HTTP/2 over
TLS. Hypercorn, however, supports the h2c HTTP/1.1 to HTTP/2 upgrade
process. This allows a client to send a HTTP/1.1 request with a
Upgrade: h2c header that results in the connection being upgraded
to HTTP/2. To test this try
$ curl --http2 http://url:port/path
Note that in the absence of either the upgrade header or an ALPN
protocol Hypercorn will assume and treat the connection as HTTP/1.1.
Hypercorn supports pipeling, flow control, and server push, it doesn’t
(as yet) support prioritisation.