WireGuard - experimental branch - PR 3 of 3

Adds service definition from [IOTstack tutorial: Quick and Dirty WireGuard](https://gist.github.com/Paraphraser/f46014b8a27e3f878f07657d6db4490e) gist, with two differences. Instead of hard-coding the following environment variables:

```
- SERVERURL=your.dynamic.dns.name
- SERVERPORT=51820
```

this PR follows the convention of using the `Unset` key:

```
- SERVERURL=Unset
- SERVERPORT=Unset
```

Adds same `duck.sh` proposed in PR 1 of 3 in this PR group.

No changes to documentation. I'm assuming there will be appropriate consolidation and rewriting of documentation as `experimental` approaches mainstream.

Author: Paraphraser

.internal/templates/services/wireguard/template.yml

@@ -1,23 +1,24 @@
 wireguard:
-  image: linuxserver/wireguard
   container_name: wireguard
-  cap_add:
-    - NET_ADMIN
-    - SYS_MODULE
+  image: ghcr.io/linuxserver/wireguard
+  restart: unless-stopped
   environment:
-    - PUID=1000
-    - PGID=1000
-    - TZ=Etc/UTC
-    - SERVERURL=Unset
-    - SERVERPORT=Unset
-    - PEERS=1
-    - PEERDNS=auto
-    - INTERNAL_SUBNET=100.64.0.0/24
-  volumes:
-    - ./services/wireguard/config:/config
-    - /lib/modules:/lib/modules
+  - PUID=1000
+  - PGID=1000
+  - TZ=Etc/UTC
+  - SERVERURL=Unset
+  - SERVERPORT=Unset
+  - PEERS=laptop,phone,tablet
+  - PEERDNS=auto
+# - INTERNAL_SUBNET=100.64.0.0/24
+  - ALLOWEDIPS=0.0.0.0/0
   ports:
-    - "51820:51820/udp"
+  - "51820:51820/udp"
+  volumes:
+  - ./volumes/wireguard:/config
+  - /lib/modules:/lib/modules:ro
+  cap_add:
+  - NET_ADMIN
+  - SYS_MODULE
   sysctls:
-    - net.ipv4.conf.all.src_valid_mark=1
-  restart: unless-stopped
+  - net.ipv4.conf.all.src_valid_mark=1

scripts/host_installers/duck.sh

@@ -1,10 +1,27 @@
-#!/bin/bash
-# Your comma-separated domains list
-DOMAINS="YOUR_DOMAINS"
+#!/usr/bin/env bash
+
+# Your DuckDNS domain (or comma-separated list of DuckDNS domains if you
+# have multiple domains associated with the same IP address).
+DOMAINS="YOURS.duckdns.org"
+
 # Your DuckDNS Token
 DUCKDNS_TOKEN="YOUR_DUCKDNS_TOKEN"
 
-# A random delay to avoid every client contacting the duckdns server at the same moment
-sleep $((RANDOM % 60))
+# is this script running in the foreground or background?
+if [ "$(tty)" = "not a tty" ] ; then
+
+   # background! Assume launched by cron. Add a random delay to avoid
+   # every client contacting DuckDNS at exactly the same moment.
+   sleep $((RANDOM % 60))
+
+fi
+
+# mark the event in case this is being logged.
+echo "$(date "+%a, %d %b %Y %H:%M:%S %z") - updating DuckDNS"
+
 # Request duckdns to update your domain name with your public IP address
-curl --silent --max-time 10 --output /dev/null "https://www.duckdns.org/update?domains=${DOMAINS}&token=${DUCKDNS_TOKEN}&ip="
+curl --max-time 10 \
+   "https://www.duckdns.org/update?domains=${DOMAINS}&token=${DUCKDNS_TOKEN}&ip="
+
+# curl does not append newline so fix that
+echo ""