dehydrated (formerly letsencrypt.sh) is a nice and simple client for obtaining free SSL certificates from Let's Encrypt. This repository contains a wrapper script which automatically pulls the host names from configured SSL websites in OS X Server, requests the appropriate certificates, and calls a hook that imports them into Keychain and sets the OS X Server to use them.
This script has been developed and tested on
- OS X 10.11.4 through 10.13.3
- Server.app 5.1 through 5.5
Older versions might work too, but have not been tested.
In Server.app, go to the Websites section and create a new web site for each domain name you intend to use. If you want multiple domains to point to the same web site, you can add these under Additional Domains. Set the port number to 443 and choose the self-signed certificate that has been created by OS X Server.
Now execute run.sh from this repository with sudo rights.