Let’s say you followed instructions in documentation at https://letsencrypt.readthedocs.org/en/latest/using.html#installation and installed Letsencrypt at /etc/letsencrypt.
Then you setup and obtained SSL certificates that are saved to /etc/letsencrypt/live/domainname.com/ directory.
But if you re-ran install again, will it override all settings in /etc/letsencrypt and wipe out the existing saved SSL certificates saved at /etc/letsencrypt/live/ ? and their keys and cert directories ?
If it is wiped out, maybe Letsencrypt client install routine should be smart enough to detect if there’s live existing config and SSL certificates, keys etc in /etc/letsencrypt back them up or take that into account ?