Dynamically update an AWS Route53 sub-domain IP address to your home router IP

update_aws_ipv4.sh

[change-resource-record-set.json]
{
  "Comment": "Updating IP address",
  "Changes": [
    {
      "Action": "UPSERT",
      "ResourceRecordSet": {
        "Name": "domain.example.com",
        "Type": "A",
        "TTL": 60,
        "ResourceRecords": [
          {
            "Value": "127.0.0.1"
          }
        ]
      }
    }
  ]
}





[update_ipv4.sh]
#!/bin/bash -eux

# retrieve the local public ip, and domian IP
export domain="domain.example.com"
export home_ipv4="$(curl -s http://whatismyip.akamai.com)";
export site_ipv4="$(dig +short $domain)";

# check if they match
if [ "$home_ipv4" == "$site_ipv4" ]
then
    # log the match, exit
    logger "$domain IP already matches"
    exit 0;
fi

# log the mismatch
logger "updating IP address for $domain to $home_ipv4"

# retrieve hostedZoneId
hostedZoneId=$(aws route53 list-hosted-zones \
  --query 'HostedZones[?Config.PrivateZone==`false`].Id' \
  --output text \
  | cut -d'/' -f3 );
echo "$hostedZoneId";

# retrieve the JSON file, change value as needed, save results
changeBatch=$({
jq '.Changes[].ResourceRecordSet.ResourceRecords[0].Value=env.home_ipv4'
} < change-resource-record-set.json);
echo "$changeBatch";


# update the record
# https://docs.aws.amazon.com/cli/latest/reference/route53/change-resource-record-sets.html
recordChangeResult=$(aws route53 change-resource-record-sets \
  --hosted-zone-id "$hostedZoneId" \
  --change-batch "$changeBatch");
echo "$recordChangeResult";

exit 0;




# update crontab, to run the script every 5 min
crontab -e
*/5 * * * * ~/update_ipv4.sh

# check the syslog to verify the script is running
grep -F "domain.example.com" /var/log/syslog