The idea of the library is to simplify certificates configuration in Erlang
programs. Typically an Erlang program which needs certificates (for HTTPS/
MQTT/XMPP/etc) provides a bunch of options such as certfile, chainfile,
privkey, etc. The situation becomes even more complicated when a server
supports so called virtual domains because a program is typically required to
match a virtual domain with its certificate. If a user has plenty of virtual
domains it's quickly becoming a nightmare for them to configure all this. The
complexity also leads to errors: a single configuration mistake and a program
generates obscure log messages, unreadable Erlang tracebacks or, even worse,
just silently ignores the errors. Fortunately, the large part of certificates
configuration can be automated, reducing a user configuration to something as
simple as:

certfiles:

  - /etc/letsencrypt/live/*/*.pem

The purpose of this library is to do this dirty job under the hood.