and got various compilation areas. I've a fairly clean Debian 9 (Stretch) install. Working my way through the missing libs, and installing: libffi-dev, gcc got me to the point where running the pip command above worked cleanly, and apparently I've successfully cargo-culted my cryptography to v1.4 Now when I run "certbot certificates" I get a meaningful output:
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Found the following certs:
Certificate Name: rfi.net
Domains: rfi.net,pub.rfi.net,www.rfi.net
Expiry Date: 2017-11-29 08:45:00+00:00 (VALID: 89 days)
...
So I think this looks good. Many thanks for the tip!