This change fixes the scenario where you reload the config and it tries to obtain a cert from the ACME server, but no email address is found or terms have not been agreed to in-process. This is unfortunate but it should not stop the server from reloading, so we assume empty email address in this case.
It is unexpected to serve localhost on port 443 or any server on 443 if TLS is disabled, even if the port is blank. Also don't warn about how to force TLS on the HTTP port.
The docs link to this structure and all its methods related to the browse template; keeping them together makes it possible to link to the whole block of code that is relevant.
Before, Caddy couldn't support graceful (zero-downtime) restarts when the reloaded Caddyfile had a host in it that was elligible for a LE certificate because the port was already in use. This commit makes it possible to do zero-downtime reloads and issue certificates for new hosts that need it. Supports only http-01 challenge at this time.
OCSP stapling is improved in that it updates before the expiration time when the validity window has shifted forward. See 30c949085cad82d07562ca3403a22513b8fcd440. Before it only used to update when the status changed.
This commit also sets the user agent for Let's Encrypt requests with a string containing "Caddy".
By separating scheme and port at the parser, we are able to set the port appropriately and also keep the semantics of the scheme being specified by the user later on. The parser also stores an address' original input. Also, the config refactor makes it possible to partially load a config - valuable for determining which ones will need Let's Encrypt integration turned on during a restart.
