Making the web more secure with free SSL certificates, Let's Encrypt is a great way to make your Ghost site run on HTTPS
We strongly recommend that all sites use SSL, and plan to make it a mandatory configuration for Ghost in the near future.
All Ghost(Pro) sites come with automatic SSL enabled by default and require no setup of any kind, so if you use our hosted platform to run Ghost: Configure a custom domain for your sites and you're all set!
ghost setup ssl
This will prompt you for a couple of details, including your email address - which is required for Let's Encrypt notifications about renewing your certificate. Your email address is not shared or used for any other purpose when entered here.
This is a normal part of the larger ghost setup CLI command.
Note: You can, of course, only setup SSL if you have a properly configured domain name. Let's Encrypt will not be able to provision a certificate for any Ghost install which is running locally, or on an IP address.
For more detailed, full install and setup guides for Ghost, make sure you check out the specific install documentation for your platform of choice.