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Automating the Cleanup of Unused Elastic IPs (EIPs) Across AWS Regions with AWS Lambda

Elastic IPs (EIPs) in AWS provide a static IPv4 address that you can associate with your AWS resources, such as EC2 instances or NAT gateways. Over time, unused EIPs can accumulate and lead to unnecessary costs. In this tutorial, we'll explore how to automate the cleanup of unused EIPs across all AWS regions using AWS Lambda and Python with Boto3.

Prerequisites

Before getting started, ensure you have the following:

• An AWS account with sufficient permissions to create Lambda functions and manage IAM roles.
• Basic knowledge of Python programming.
• Basic familiarity with AWS services such as Lambda and EC2.

Step 1: Create a Lambda Function

1. Navigate to the AWS Management Console and open the AWS Lambda service.
2. Click on "Create function" and choose "Author from scratch".
3. Enter a name for your function, select the appropriate runtime (Python 3.x), and choose an existing IAM role with permissions to describe and release Elastic IPs.
4. Click on "Create function" to create the Lambda function.

Step 2: Write the Lambda Function Code

Now, let's write the Python code for our Lambda function. Replace the default function code with the following:

import boto3

def lambda_handler(event, context):
    client = boto3.client('ec2')
    regions = [region['RegionName'] for region in client.describe_regions()['Regions']]

    for region in regions:
        ec2_client_region = boto3.client('ec2', region_name=region)
        addresses = ec2_client_region.describe_addresses()['Addresses']
        
        for eip in addresses:
            if ('AssociationId' not in eip) and ('NetworkInterfaceId' not in eip):
                ec2_client_region.release_address(AllocationId=eip['AllocationId'])
    
    return {
        'statusCode': 200,
        'body': 'Unused Elastic IPs deleted successfully across all regions!'
    }

This code iterates through all AWS regions, describes the Elastic IPs in each region, and releases any unused Elastic IPs.

Step 3: Configure Triggers and Permissions

1. Configure a trigger for your Lambda function, such as a CloudWatch Events trigger to schedule the function execution.
2. Ensure that the IAM role associated with your Lambda function has permissions to describe and release Elastic IPs across all regions. You can create a custom IAM policy with the necessary permissions and attach it to the IAM role.

Step 4: Test the Lambda Function

Once your Lambda function is configured and deployed, you can test it by manually invoking the function. Monitor the CloudWatch Logs for your Lambda function to ensure it executes successfully and deletes unused Elastic IPs across all regions.

Conclusion

In this tutorial, we've demonstrated how to automate the cleanup of unused Elastic IPs across all AWS regions using AWS Lambda and Python with Boto3. By regularly running this Lambda function, you can ensure that your AWS account remains free of unnecessary resources and reduce costs associated with unused Elastic IPs.

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