Proposal Details

Expose a Protocols or DisableHTTP1 option on http.Server that allows serving HTTP/2 without falling back to HTTP/1.1.

Currently, enabling HTTP/2 (including h2c) with net/http always implies enabling HTTP/1.1, since the HTTP/2 implementation is layered on top of the HTTP/1.1 server. There’s no way to refuse HTTP/1.1 connections while still accepting HTTP/2.

• Operators who wish to deprecate or disable HTTP/1.1 for security/operational reasons (see http1mustdie.com)
• Other modern servers (nginx, Envoy, etc.) allow administrators to explicitly disable HTTP/1.1 while continuing to serve HTTP/2
• As the ecosystem moves away from HTTP/1.1, lack of configurability in Go prevents projects like Caddy from allowing blocking of HTTP/1.1