Dynamics DNS script for Route53

route53_dyndns.sh

#!/bin/sh

IP="$(curl -s https://checkip.amazonaws.com/)"
ZONEID="AWSZ0N3IDH3R3"
DOMAIN="subdomain.example.com"

DNS="$(mktemp)"

cat > "${DNS}" <<EOF
{
  "Comment": "DDNS update",
  "Changes": [
    {
      "Action": "UPSERT",
      "ResourceRecordSet": {
        "ResourceRecords": [
          {"Value": "${IP}"}
        ],
        "Name": "${DOMAIN}",
        "Type": "A",
        "TTL": 300
      }
    }
  ]
}
EOF

DNSIP="$(dig +short ${DOMAIN})"
ROUTE53IP="$(aws route53 list-resource-record-sets --hosted-zone-id ${ZONEID} --query "ResourceRecordSets[?Name == '${DOMAIN}.']" | jq -r '.[0].ResourceRecords[0].Value')"
echo Current IP: $IP
echo DNS IP: $DNSIP
echo Route 53 IP: $ROUTE53IP

if [ "$IP" = "$ROUTE53IP" ];
then
    echo IPs match, nothing to do
else
    echo IPs differ, need to update DNS

    aws route53 change-resource-record-sets --hosted-zone-id "/hostedzone/${ZONEID}" --change-batch "file://${DNS}"
fi

rm "${DNS}"