update the dynamic dns endpoint address in wireguard when the remote ip has changed

update_WG_DDNS_endpoint

#!/bin/bash
# update_WG_DDNS_endpoint
# update the dynamic dns endpoint address in wireguard when the remote ip has changed

set -e

WG_IFACE="wg0"
WG_PEER="your peer"
WG_ENDPOINT="ddns.test.name:port"
PUBLICIP="/tmp/publicIP"

[ -f "$PUBLICIP" ] || touch "$PUBLICIP"

# get current DDNS IP address
CURRENT_IP=$(host -4 -t A ddns.test.name | awk '{print $5}' 2>/dev/null)
echo "Current ednpoint IP is" $CURRENT_IP

# validate IP address
if [[ ! $CURRENT_IP =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
    exit 1
fi

PREVIOUS_IP=$(tail -n 1 "$PUBLICIP")

# update endpoint
if [ "$CURRENT_IP" != "$PREVIOUS_IP" ]; then
    echo "Updating endpoint IP to $CURRENT_IP"
    echo $CURRENT_IP >"$PUBLICIP"
    # update wireguard endpoint
    sudo wg set $WG_IFACE peer $WG_PEER endpoint $WG_ENDPOINT
else
    echo "IP address has not changed"
fi

echo "##### All Done! #####"