さくらのクラウド「DNS」でDynamicDNS

export SAKURACLOUD_ACCESS_TOKEN=(your access token)
export SAKURACLOUD_ACCESS_TOKEN_SECRET=(your access token secret)

DDNS_ZONE="example.net"
DDNS_DOMAIN="sub.domain"

#!/bin/bash
set -eu

BASEDIR=$(dirname "$0")
cd ${BASEDIR}

. ${BASEDIR}/config.sh

sleep $[ ( $RANDOM % 30 )  + 1 ]s

touch lastaddr.txt
OLDADDR=$(cat lastaddr.txt)
NEWADDR=$(curl -s -f https://httpbin.org/ip | jq -r .origin)
if [ "${OLDADDR}" = "${NEWADDR}" ]; then
    exit 0
fi
if [ "${NEWADDR}" = "null" ]; then
    exit 1
fi
echo "Address changed: ${OLDADDR} -> ${NEWADDR}"
echo ${NEWADDR} > lastaddr.txt

/usr/local/bin/sacloudns rset --zone=${DDNS_ZONE} --ttl=300 --name=${DDNS_DOMAIN} --type=A --data=${NEWADDR}