dyndns script for digitalocean, with ipv6 support

do-dyndns.sh

#!/bin/bash
# Original script by https://salvatorelab.com/2020/10/how-to-point-a-domain-to-your-dynamic-home-ip-address/
# IPv6 additions by rickyh.me

# To obtain RECORD_IDs:
# curl GET -H "Content-Type: application/json" \
#    -H "Authorization: Bearer TOKEN" \
#    https://api.digitalocean.com/v2/domains/yourdomain.info/records | json_pp 

#################### CHANGE THE FOLLOWING VARIABLES ####################
TOKEN="YOUR_API_TOKEN_HERE"
DOMAIN="YOUR_DOMAIN.EXAMPLE"
IPV4_RECORD_ID=""
IPV6_RECORD_ID=""
LOG_FILE="/var/log/do-dyndns.log"
########################################################################

CURRENT_IPV4="$(dig +short myip.opendns.com @resolver4.opendns.com)"
CURRENT_IPV6="$(dig -6 -t aaaa +short myip.opendns.com @resolver1.opendns.com)"

LAST_IPV4="$(tail -1 $LOG_FILE | awk -F, '{print $2}')"

if [ "$CURRENT_IPV4" = "$LAST_IPV4" ]; then
    echo "IP has not changed ($CURRENT_IPV4)"
    echo $CURRENT_IPV6
else
    echo "IP has changed: $CURRENT_IPV4"
    echo $CURRENT_IPV6
    echo "$(date),$CURRENT_IPV4" >> "$LOG_FILE"
    curl -X PUT -H "Content-Type: application/json" -H "Authorization: Bearer $TOKEN" -d '{"data":"'"$CURRENT_IPV4"'"}' "https://api.digitalocean.com/v2/domains/$DOMAIN/records/$IPV4_RECORD_ID"
    curl -X PUT -H "Content-Type: application/json" -H "Authorization: Bearer $TOKEN" -d '{"data":"'"$CURRENT_IPV6"'"}' "https://api.digitalocean.com/v2/domains/$DOMAIN/records/$IPV6_RECORD_ID"