Updating Route 53 automatically when Auto Scaling brings up new instance - amazon-web-services

Question

I am using Amazon EC2 Auto Scaling in my environment, whenever Auto Scaling triggers a new instance, I need to change the IP manually in Route 53. I want to automate this process.
Tried using Lifecycle Hooks but didn't see any update for Route 53.

Answer 1

You can use this User Data script to update the Route 53 record when an instance is launched.
It gathers required information from Instance Metadata.
#!
INSTANCE_ID=$(curl http://169.254.169.254/latest/meta-data/instance-id)
PRIVATE_IP=$(curl http://169.254.169.254/latest/meta-data/local-ipv4)
DOMAIN_NAME=$(aws route53 get-hosted-zone --id "${HOSTED_ZONE_ID}" --query 'HostedZone.Name' --output text | sed 's/.$//')
hostnamectl set-hostname hostname."${DOMAIN_NAME}"
aws route53 change-resource-record-sets --hosted-zone-id "${HOSTED_ZONE_ID}" --change-batch '{"Changes": [{"Action": "UPSERT","ResourceRecordSet": {"Name": "'"$(hostname)"'","Type": "A","TTL": 60,"ResourceRecords": [{"Value": "'"${PRIVATE_IP}"'"}]}}]}'
You would need to insert a value for the ${HOSTED_ZONE_ID} to identify the record to update.
EDIT:
If You have multiple instances provisioned by ASG, You can develop a script to name new host.
I.e:
Use ASG to apply "role" TAG to every instance provisioned by ASG i.e role=webserver
In userdata script list all instances with TAG role=webserver
Check returned instances for TAG "node"
If none, then this instance is node1 -> hostname webserver-node1.${DOMAIN_NAME}
If some, parse TAG "node" to check which instance was replaced by ASG. I.e in result you can have node=node1, node=node3, node=node4. node2 is missing, so this instance is node2 -> hostname webserver-node2.${DOMAIN_NAME}
At the end of userdata you have to add "node" TAG to this instance, so next one is not named as existing one.

Answer 2

# !/bin/bash
INSTANCE_ID=$(curl http://169.254.169.254/latest/meta-data/instance-id)
PRIVATE_IP=$(curl http://169.254.169.254/latest/meta-data/local-ipv4)
DOMAIN_NAME=$(aws route53 get-hosted-zone --id "<Hosted Zone ID >" --query 'HostedZone.Name' --output text | sed 's/.$//')
hostnamectl set-hostname hostname."${DOMAIN_NAME}"
CN=`echo $PRIVATE_IP | cut -d . -f 3`
echo $CN
a=5
if [ $CN == $a ]
then
aws route53 change-resource-record-sets --hosted-zone-id "<Hosted Zone ID >" --change-batch '{"Changes": [{"Action": "UPSERT","ResourceRecordSet": {"Name": "'"Dns Name"'","Type": "A","TTL": 60,"ResourceRecords": [{"Value": "'"${PRIVATE_IP}"'"}]}}]}'
else
aws route53 change-resource-record-sets --hosted-zone-id "<Hosted Zone ID >" --change-batch '{"Changes": [{"Action": "UPSERT","ResourceRecordSet": {"Name": "'"< Dns Name>"'","Type": "A","TTL": 60,"ResourceRecords": [{"Value": "'"${PRIVATE_IP}"'"}]}}]}'
fi