Since Cowboy 2.14.0 an experimental implementation of HTTP/3 (or QUIC or RFC9000) has been released. That's a pretty good news, and if stable enough, will change a lot on the web ecosystem. Unfortunately, this feature is not documented yet - because unstable - but it's not a good reason to play with it and try to understand how to configure a cowboy server with HTTP/3 and QUIC.
Cowboy does not support natively QUIC and depends on quicer application to work correctly. To be clear, this is a BIG NO-NO for a deployment in production environment. The list of dependencies directly required by quicer is insane, it fetch many python-like modules and recompile OpenSSL from scratch (OpenSSL 3.1.7+quic, from an unmaintained and archived repository, with all security issues that could implies).
Anyway, the COWBOY_QUICER Erlang macro must be set to 1 to compile cowboy with HTTP/3 and QUIC support. Then, the rebar.config file will need few modifications. The configuration for the cowboy dependency must be overridden and the previous macro must be activated. The quicer depency is also required, because this is an experimental feature, cowboy does not include it. To test that, let reuse the buckaroo project created in a previous publication.
