trillium-acme: support for automatic HTTPS certificates via ACME using rustls-acme

[joshtriplett]

I'd love to add a trillium-acme crate that enables automatic HTTPS certificates for Trillium, via Let's Encrypt and ACME tls-alpn-01 challenges. Would you be open to the addition of a trillium-acme crate based on rustls-acme?

[joshtriplett]

I'm experimenting with making this work, and running into some difficulties.

rustls-acme has two interfaces:

• A low-level interface built on futures-rustls that provides an Acceptor-style interface. When using this interface, some of the requests will be validation requests, in which case they need to be ignored and not passed along to trillium. However, trillium's Acceptor interface (unlike, for instance, Tide's) requires returning a stream or an error; Tide's includes an Option, so you can return Ok(None) for "no error, but there's no connection to handle here".
• A high-level interface that handles all the details, and just provides a stream of streams. It doesn't seem like trillium has a way to use such an interface without implementing a separate server type from scratch.

I think the easiest solution here would be to modify the Acceptor interface to use Option, and then anything using Acceptor can silently ignore None. That would be a breaking change to trillium_server_common and things directly using Acceptor. Would that be acceptable? Could I send in a PR for that?

[joshtriplett]

#376

[joshtriplett]

Update: ignore this thread and see #377 instead.

[joshtriplett]

Implemented in #377

[joshtriplett]

I've now published a trillium-acme crate.