synology: Add acme.sh + Resilio Sync script

This commit adds a script that I use to copy over Let's Encrypt
certificates to Resilio Sync on a Synology NAS.

synology/README.md

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+# Synology NAS Scripts
+
+This directory contains scripts that I use on my Synology NAS.

synology/acme.sh-rslsync.sh

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+#!/bin/bash
+# Injabie3 - 2024-04-24
+# Let's Encrypt for Resilio Sync
+#
+# Description:
+# A script to renew the Let's Encrypt certificate and then subsequently copy it
+# into a directory to use with Resilio Sync on a Synology NAS.
+#
+# Pre-requisites:
+# acmesh-official/acme.sh is used to manage the certificate. Detailed instructions
+# can be found at https://github.com/acmesh-official/acme.sh/wiki/Synology-NAS-Guide
+# tl;dr: This script assumes that acme.sh is located at `/usr/local/share/acme.sh`.
+#
+# Usage:
+# 1. Add the contents of this script to your Task Scheduler in DSM.
+# 2. Stop the Resilio Sync service.
+# 3. Ensure your sync.conf file has the following keys set in the webui section:
+#    "force_https": true,
+#    "ssl_certificate": "/volume1/@appstore/resiliosync/var/cert/cert.pem",
+#    "ssl_private_key": "/volume1/@appstore/resiliosync/var//cert/privkey.pem"
+#
+#    On DSM 7 and Resilio Sync 2.7.3, if Resilio Sync is installed on Volume 1, then
+#    this file is located at: `/volume1/@appstore/resiliosync/var/`.
+# 4. Restart the Resilio Sync service.
+
+#################
+# Configuration #
+#################
+export fqdnForNas=nas.example.com
+export acmeShRoot=/usr/local/share/acme.sh
+export synologyCertDir=/usr/syno/etc/certificate/system/default
+export rslsyncCertDir=/volume1/@appstore/resiliosync/var/cert
+
+# Here's the actual script
+${acmeShRoot}/acme.sh --renew -d "${fqdnForNas}" --home ${acmeShRoot}
+cp ${synologyCertDir}/cert.pem ${rslsyncCertDir}/cert.pem
+cp ${synologyCertDir}/privkey.pem ${rslsyncCertDir}/privkey.pem
+chown rslsync:resiliosync ${rslsyncCertDir}/cert.pem
+chown rslsync:resiliosync ${rslsyncCertDir}/privkey.pem
+chmod 600 ${rslsyncCertDir}/cert.pem
+chmod 600 ${rslsyncCertDir}/privkey.pem