Letsencrypt on Synology DSM 7

README.md

The goal is to configure Synology NAS to use letsencrypt certificate without exposing it to the internet.
To achieve this we use certbot with DNS-01 challenge to Cloudflare.

1. Run install.sh to install pip and certbot. You may need to run this again after DSM upgrades.

2. Setup cloudflare secret.

# mkdir /volume1/system/.secrets
# touch /volume1/system/.secrets/cloudflare.ini
# chmod 700 /volume1/system/.secrets
# chmod 600 /volume1/system/.secrets/cloudflare.ini

Add the Cloudflare API key in this file: https://certbot-dns-cloudflare.readthedocs.io/en/stable/#credentials

3. Generate certificate.

# certbot certonly --dns-cloudflare \
   --dns-cloudflare-credentials /volume1/system/.secrets/cloudflare.ini \
   -d nas.mydomain.com --preferred-challenges dns-01

4. Save import_certs.sh and run it.
   It's a good idea to backup /usr/syno/etc/certificate first.

5. Setup a scheduled task within DSM to run renew.sh, you could also use cron.

import_certs.sh

#!/bin/sh

CERT=nas.mydomain.com
REVERSE_PROXY=/usr/syno/etc/certificate/ReverseProxy
DEFAULT_DIR=
DEFAULT_DIR_NAME=$(cat /usr/syno/etc/certificate/_archive/DEFAULT)
if [ "DEFAULT_DIR_NAME" != "" ]; then
	DEFAULT_DIR="/usr/syno/etc/certificate/_archive/${DEFAULT_DIR_NAME}"
fi

# Copy certs from letsencrypt to install directory
cp /etc/letsencrypt/live/$CERT/{privkey,fullchain,cert}.pem /usr/syno/etc/certificate/system/default/

# Ensure correct permissions
chown root:root /usr/syno/etc/certificate/system/default/{privkey,fullchain,cert}.pem

# Replace certs for default Application Portal (if found)
if [ -d "$DEFAULT_DIR" ]; then
    cp /usr/syno/etc/certificate/system/default/{privkey,fullchain,cert}.pem "$DEFAULT_DIR/"
    chown root:root "$DEFAULT_DIR/"{privkey,fullchain,cert}.pem
else
	echo "Did not find Application Portal dir: $DEFAULT_DIR_NAME"
fi

# Replace certs for all reverse proxy servers (if exists)
if [ -d "$REVERSE_PROXY" ]; then
	for proxy in $(ls "$REVERSE_PROXY"); do
		cp /usr/syno/etc/certificate/system/default/{privkey,fullchain,cert}.pem "$REVERSE_PROXY/$proxy"
		chown root:root "$REVERSE_PROXY/$proxy/"{privkey,fullchain,cert}.pem
	done
else
	echo "No reverse proxy directory found"
fi

echo "Certs moved."

# Restart synology services
echo -n "Restarting..."
/usr/syno/bin/synosystemctl restart nginx
/usr/syno/bin/synosystemctl restart avahi
echo " done"

install.sh

#!/bin/bash
python3 -m ensurepip
python3 -m pip install --upgrade pip
python3 -m pip -V
pip install certbot-dns-cloudflare

renew.sh

#!/bin/sh
/bin/certbot renew --post-hook "/volume1/system/script/letsencrypt/import_certs.sh"