AWS EC2 Dynamic DNS

0-aws-dynamic-dns.md

AWS EC2 Dynamic DNS

Use the provided script to update your Route 53 domain name to point to the EC2 instance IP address that changes dynamically on reboot.

# configure crontab
sudo -i
chmod ug=rx,o= /root/update-dns.sh
systemctl enable cron.service
crontab -e

# crontab file
@reboot /root/update-dns.sh

1-ec2-update-dns.sh

#!/bin/bash

HOSTED_ZONE_ID=""
NAME="example.com."
TYPE="A"
TTL=60


IP=$(curl http://checkip.amazonaws.com/)

if [[ ! $IP =~ ^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}$ ]]; then
  echo "Failed to obtain IP address"
  exit 1
fi

echo "Updating A-record to point to: $IP"

cat > /tmp/route53_changes.json << EOF
{
  "Comment":"Updated From DDNS Shell Script",
  "Changes": [
    {
      "Action": "UPSERT",
      "ResourceRecordSet": {
        "ResourceRecords": [{ "Value":"$IP" }],
        "Name": "$NAME",
        "Type": "$TYPE",
        "TTL": $TTL
      }
    }
  ]
}
EOF

aws route53 change-resource-record-sets \
  --hosted-zone-id $HOSTED_ZONE_ID \
  --change-batch file:///tmp/route53_changes.json >> /dev/null

echo "Done"

2-ec2-update-dns-policy.json

{
	"Version": "2012-10-17",
	"Statement": [
		{
			"Effect": "Allow",
			"Action": "ec2:DescribeTags",
			"Resource": "*"
		},
		{
			"Effect": "Allow",
			"Action": "route53:ChangeResourceRecordSets",
			"Resource": "arn:aws:route53:::hostedzone/Z310AKR6T33BBU"
		},
		{
			"Effect": "Allow",
			"Action": "route53:ChangeResourceRecordSets",
			"Resource": "arn:aws:route53:::hostedzone/Z0466444CI3IIHSFDP5"
		}
	]
}