https://certbot.eff.org/#ubuntuxenial-other
Install
On Ubuntu systems, the Certbot team maintains a PPA. Once you add it to your list of repositories all you'll need to do is apt-get the following packages.
$ sudo apt-get update $ sudo apt-get install software-properties-common $ sudo add-apt-repository ppa:certbot/certbot $ sudo apt-get update $ sudo apt-get install certbot
Get Started
Certbot supports a number of different “plugins” that can be used to obtain and/or install certificates.
Since your server architecture doesn't yet support automatic installation you'll have to use the certonly command to obtain your certificate.
$ sudo certbot certonly