@mnordhoff
As suggested by user gery at PIP error with certbot-auto , I made the following changes to certbot-auto:
pip_version = StrictVersion(check_output([python, '-m', 'pip', '--version'])
by
pip_version = StrictVersion(check_output(['pip', '--version'])
and
command = [python, '-m', 'pip', 'install', '--no-index', '--no-deps', '-U']
by
command = ['pip', 'install', '--no-index', '--no-deps', '-U']
Then I ran the following:
$ /opt/letsencrypt/certbot-auto certonly --config /etc/letsencrypt/cli.ini -w /var/www/avvau.com/public_html -d avvau.com -d www.avvau.com
It gave the following response:
/opt/eff.org/certbot/venv/local/lib/python2.7/site-packages/cryptography/hazmat/primitives/constant_time.py:26: CryptographyDeprecationWarning: Support for your Python version is deprecated. The next version of cryptography will remove support. Please upgrade to a 2.7.x release that supports hmac.compare_digest as soon as possible.
utils.PersistentlyDeprecated2018,
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for avvau.com
http-01 challenge for www.avvau.com
Using the webroot path /var/www/avvau.com/public_html for all unmatched domains.
Waiting for verification...
Cleaning up challenges
IMPORTANT NOTES:
- Congratulations! Your certificate and chain have been saved at:
/etc/letsencrypt/live/avvau.com-0001/fullchain.pem
Your key file has been saved at:
/etc/letsencrypt/live/avvau.com-0001/privkey.pem
Your cert will expire on 2019-07-12. To obtain a new or tweaked
version of this certificate in the future, simply run certbot-auto
again. To non-interactively renew *all* of your certificates, run
"certbot-auto renew"
So, it worked. Thanks for your help!