It collects the ELB's private IPs from EC2 network interfaces within a specified VPC. It fetches the existing Route53 records to check for differences. If the IPs have changed, it updates the Route53 A record.

record_private_ips_alb.py

import boto3
import sys

# AWS Configuration
vpc_id = 'your-vpc-id'
elb_network_description = 'Your ELB network interface description (generated like "ELB your-elb-name")'
route53_internal_hosted_zone_id = 'Your Route53 Internal hosted zone ID'
route53_internal_record_name = 'your-route53-record.internal.'  # Ending with dot

aws_access_key = 'Your IAM Key'
aws_secret_key = 'Your IAM Secret'
aws_region = 'us-west-1'

# Initialize EC2 client
ec2_client = boto3.client(
    'ec2',
    region_name=aws_region,
    aws_access_key_id=aws_access_key,
    aws_secret_access_key=aws_secret_key
)

# Get ELB network interfaces
response = ec2_client.describe_network_interfaces(
    Filters=[
        {'Name': 'description', 'Values': [elb_network_description]},
        {'Name': 'vpc-id', 'Values': [vpc_id]}
    ]
)

# Collect ELB IPs
elb_ips = sorted([interface['PrivateIpAddress'] for interface in response['NetworkInterfaces']])

# Initialize Route53 client
route53_client = boto3.client(
    'route53',
    region_name='us-east-1',  # Route53 operates globally, but us-east-1 is typically used
    aws_access_key_id=aws_access_key,
    aws_secret_access_key=aws_secret_key
)

# Get existing Route53 record IPs
records = route53_client.list_resource_record_sets(
    HostedZoneId=route53_internal_hosted_zone_id,
    StartRecordName=route53_internal_record_name
)

route53_elb_ips = sorted([record['Value'] for record in records['ResourceRecordSets'][0]['ResourceRecords']])

# Check if update is needed
if elb_ips == route53_elb_ips:
    print('Same IPs detected - no update needed')
    sys.exit()

# Prepare new records
route53_resource_records = [{'Value': ip} for ip in elb_ips]

# Update Route53 records
route53_client.change_resource_record_sets(
    HostedZoneId=route53_internal_hosted_zone_id,
    ChangeBatch={
        'Comment': 'ELB Private IPs update',
        'Changes': [
            {
                'Action': 'UPSERT',
                'ResourceRecordSet': {
                    'Name': route53_internal_record_name,
                    'TTL': 60,
                    'Type': 'A',
                    'ResourceRecords': route53_resource_records
                }
            }
        ]
    }
)

print('Route53 record updated successfully.')