Configure Let's Encrypt service with Pound server

On this tutorial I will show you how to configure your Pound proxy server so it can take advantage of the awesome SSL service provided by Let's Encrypt.

Let's Encrypt is an open-source certificate authority that issues SSL certificates for free making use of the ACME protocol, making possible to obtain trusted certificates for your websites and operate under HTTPS:// with no browser warnings and securing your content of course.

The services also provides a command line tool called Certbot, that can be easily installed on any Linux OS and it will help creating the necessary steps in order to create the certificates for an specific domain/website.

In order to install Certbot on your server, follow the next steps: (make sure you have "git" installed on your system)

$sudo apt-get install git (if not previously installed)
$cd /opt
$sudo git clone https://github.com/certbot/certbot

Running the above commands will download the Certbot latest release from their git repo in the /opt folder. Then we need to stop any service that might be using port 80 on our server, since the installation type we will be performing on this tutorial is the "standalone" type described on the Cerbot documentation, there are other ways to install the certificates, it is up to your preference.
Since this tutorial is about Pound, we are assuming the daemon is already installed so we need to stop it:

$sudo service pound stop

once the service is stopped, run:

$cd /opt/certbot
$sudo ./letsencrypt-auto --text --email YOUR@EMAIL -d YOUR_DOMAIN --agree-tos --standalone certonly

by default, running the command above will generate the necessary key files (*.pem) in the following folder:

/etc/letsencrypt/live/YOUR_DOMAIN/

now, we need to create a private key file that Pound can understand, to do so run the following:

$sudo cat /etc/letsencrypt/live/YOUR_DOMAIN/privkey.pem /etc/letsencrypt/live/YOUR_DOMAIN/fullchain.pem > /etc/ssl/YOUR_DOMAIN.pem

doing so, will concatenate the privkey.pem file and the fullchain.pem file generated by Cerbot into a single file that will be stored into your ssl certificates folder, this is very important!

In order to enable your certificate we need to edit the Pound configuration file and add the entry for it:

$sudo nano /etc/pound/pound.cfg

on the HTTPS section add:

Cert    "/etc/ssl/YOUR_DOMAIN.pem"

And thats pretty much it, you can start Pound back again:

$sudo service pound start

and your domain will be secured by Let's Encrypt! Keep in mind that these certificates have an expiration period of 90 days, so you might have to manually renew using Cerbot each certificate, in order to avoid this process, you can automate it by adding a cron task that will auto renew your certificates for you. To do so, run the following commands:

$sudo nano /etc/cron.monthly/letsencrypt

and add the following:

#!/usr/bin/env bash
cd /opt/certbot
./certbot-auto renew \
--noninteractive \
--pre-hook "service pound stop" \
--post-hook "service pound start"

Here is a nice sh script you can use to register multiple domains with pound:

https://github.com/ffonaissak/letsencrypt-pound/blob/master/letsencrypt-pound.sh

Here's a complete tutorial including certificate auto renew:

https://serversforhackers.com/video/letsencrypt-for-free-easy-ssl-certificates

Enjoy!