This is a tiny, auditable script that you can throw on your server to issue and
renew Let's Encrypt certificates. Since it has to be run on your server and
have access to your private Let's Encrypt account key, I tried to make it as
tiny as possible (currently less than 200 lines). The only prerequisites are
python and openssl.

Well, that and a web server - but then you only need this with a web server.
This package adds a simple directory layout and timer service that runs
acme_tiny on installed CSRs as the acme user for privilege separation.