Support for auto_tls

[werdnum]

I was wondering what it would take to get the automatic TLS integration working properly.

I don't know too much about Caddy, but in the absence of any other mechanism for cross-server shared state, I was thinking about stuffing the tailscale Server object in a global map under the tailscale package, keyed by tsnet.Server.CertDomains(), and then calling s.LocalClient.CertPair().

It isn't the prettiest design, but I'm welcome to other suggestions if you know of a better way to share state between the cert manager and the listener.

If you're OK with that design, I could probably whip something up over the next few days.

[mholt]

Just to clarify, what isn't working properly?

[werdnum]

I'm referring to the shortcomings mentioned here: https://github.com/tailscale/caddy-tailscale#https-support (i.e., that the native TLS integration doesn't work and you need to use tailscale+tls instead (and set auto_tls off).

In particular, I'm hoping to have a single server run as a bidirectional HTTP proxy (serve a local service over tailscale+tls and also provide a gateway for that service to contact other services on the tailnet)