How can I get more free SSL certificates from Let's Encrypt?

We are currently shipping all proServers with the settings for the Let's Encrypt staging servers, as the quota for subdomain certificates for the domain punkt.de has been exhausted.

To use the Let's Encrypt live servers, you must change the CA in /usr/local/etc/dehydrated/config to https://acme-v02.api.letsencrypt.org/directory.

The desired domains are entered into the domains.txt file. All domains for which a single (multi-domain) certificate is to be requested must be listed on a single line, separated only by a space. Wildcard certificates are not currently supported.

$ cat /var/www/letsencrypt/domains.txt

example.org www.example.org
example.com www.example.com wiki.example.com

To apply for an SSL certificate with Let's Encrypt, the DNS record for this domain must already point to proServer.

Next, you'll need to enable a cron job:

$ sudo crontab -u root -e

# Dehydrated Cronjob
PATH=/bin:/usr/bin:/usr/local/bin
@weekly /usr/local/bin/dehydrated -c -g

Now all that's left to do is apply for the certificates and enter the corresponding domains into the web server configuration:

$ sudo dehydrated -c

Done. The newly generated certificates are now located at /usr/local/etc/ssl/certs/<domainname>/

For more information about the tool we used, visit GitHub or letsencrypt.org.