Letsencrypt add domain to existing certificate
You can replace the certificate by just running the certbot again with ./certbot-auto certonly
You will be prompted with this message if you try to generate a certificate for a domain that you have already covered by an existing certificate:
-------------------------------------------------------------------------------
You have an existing certificate that contains a portion of the domains you
requested (ref: /etc/letsencrypt/renewal/<domain>.conf)
It contains these names: <domain>
You requested these names for the new certificate: <domain>,
<the domain you want to add to the cert>.
Do you want to expand and replace this existing certificate with the new
certificate?
-------------------------------------------------------------------------------
Just chose Expand and replace it.
Apache on Ubuntu, using the Apache plugin:
sudo certbot certonly --cert-name example.com -d m.example.com,www.m.example.com
The above command is vividly explained in the Certbot user guide on changing a certificate's domain names. Note that the command for changing a certificate's domain names applies to adding new domain names as well.
Edit
If running the above command gives you the error message
Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA.
follow these instructions from the Let's Encrypt Community
This is how i registered my domain:
sudo letsencrypt --apache -d mydomain.com
Then it was possible to use the same command with additional domains and follow the instructions:
sudo letsencrypt --apache -d mydomain.com,x.mydomain.com,y.mydomain.com
You need to specify all of the names, including those already registered.
I used the following command originally to register some certificates:
/opt/certbot/certbot-auto certonly --webroot --agree-tos -w /srv/www/letsencrypt/ \
--email [email protected] \
--expand -d example.com,www.example.com
... and just now I successfully used the following command to expand my registration to include a new subdomain as a SAN:
/opt/certbot/certbot-auto certonly --webroot --agree-tos -w /srv/www/letsencrypt/ \
--expand -d example.com,www.example.com,click.example.com
From the documentation:
--expand "If an existing cert covers some subset of the requested names, always expand and replace it with the additional names."
Don't forget to restart the server to load the new certificates if you are running nginx.