An AWS Elastic IP (EIP) address is a static, public, and unique IPv4 address. Allocated exclusively to your AWS account, the EIP remains under your control until you decide to release it. It can be allocated to your Amazon Elastic Compute Cloud (Amazon EC2) instance or other AWS resources such as load balancers.

EIP addresses are designed for dynamic cloud computing because they can be re-mapped to another instance to mask any disruptions. These EIPs are also used for applications that must make external requests to services that require a consistent address for allow listed inbound connections. As your application usage varies, these EIPs might see sporadic use over weeks or even months, leading to potential accumulation of unused EIPs that may inadvertently inflate your AWS expenditure.

In this post, we show you how to analyze EIP usage history using AWS CloudTrail and Amazon Athena to have a better insight of your EIP usage pattern in your AWS account. You can use this solution regularly as part of your cost-optimization efforts to safely remove unused EIPs to reduce your costs.

Solution overview

This solution uses activity logs from CloudTrail and the power of Athena to conduct a comprehensive analysis of historical EIP attachment activity within your AWS account. CloudTrail, a critical AWS service, meticulously logs API activity within an AWS account.

Athena is an interactive query service that simplifies data analysis in Amazon Simple Storage Service (Amazon S3) using standard SQL. It is a serverless service, eliminating the need for infrastructure management and costing you only for the queries you run.

By extracting detailed information from CloudTrail and querying it using Athena, this solution streamlines the process of data collection, analysis, and reporting of EIP usage within an AWS account.

To gather EIP usage reporting, this solution compares snapshots of the current EIPs, focusing on their most recent attachment within a customizable 3-month period. It then determines the frequency of EIP attachments to resources. An attachment count greater than zero suggests that the EIPs are actively in use. In contrast, an attachment count of zero indicates that these EIPs are idle and can be released, aiding in identifying potential areas for cost reduction.

In the following sections, we show you how to deploy the solution using AWS CloudFormation and then run an analysis.

Prerequisites

Complete the following prerequisite steps:

  1. If your account doesn’t have CloudTrail enabled, create a trail, then capture the S3 bucket name to use later in the implementation steps.
  2. Download the CloudFormation template from the repository. You need this template.yaml file for the implementation steps.

Deploy the solution

In this section, you use AWS CloudFormation to create the required resources. AWS CloudFormation is a service that helps you model and set up your AWS resources so that you can spend less time managing those resources and more time focusing on your applications that run in AWS.

The CloudFormation template creates Athena views and a table to search past AssociateAddress events in CloudTrail, an AWS Lambda function to collect snapshots of existing EIPs, and an S3 bucket to store the analysis results.

Complete the following steps:

  1. On the AWS CloudFormation console, choose on Create stack and choose With new resources (standard).
  2. In the Specify Template section, choose an existing template and upload the template.yaml file downloaded from the prerequisites.
  3. In the Specify stack details section, enter your preferred stack name and the existing CloudTrail S3 location, and maintain the default settings for the other parameters.
  4. At the bottom of the Review and create page, select the acknowledgement check box, then choose Submit.

Wait for the stack to be created. It should take a few minutes to complete. You can open the AWS CloudFormation console to view the stack creation process.

Run an analysis

You have configured the solution to run your EIP attachments analysis. Complete the following steps to analyze your EIP attachment history. If you’re using Athena for the first time in your account, you need to set up a query result location in Amazon S3.

  1. On the Athena console, navigate to the query editor.
  2. For Database, choose default.
  3. Enter the following query and choose Run query:
select eip.publicip,
eip.allocationid,
eip.region,
eip.accountid,
eip.associationid, eip.PublicIpv4Pool,
max(associate_ip_event.eventtime) as latest_attachment,
count(associate_ip_event.associationid) as attachmentCount
from eip LEFT JOIN associate_ip_event on associate_ip_event.allocationid = eip.allocationid group by 1,2,3,4,5,6

All the required tables are created under the default database.

You can now run a query on the CloudTrail logs to look back in time for the EIP attachment. This query provides you with better insight to safely release idle EIPs in order to reduce costs by displaying how frequently each specific EIP was previously attached to any resources.

This report will provide the following information:

  • Public IP
  • Allocation ID (the ID that AWS assigns to represent the allocation of the EIP address for use with instances in a VPC)
  • Region
  • Account ID
  • latest_attachment date (the last time EIP was attached to a resource)
  • attachmentCount (number of attachments)
  • The association ID for the address (if this field is empty, the EIP is idle and not attached to any resources)

The following screenshot shows the query results.

Clean up

To optimize cost, clean up the resources you deployed for this post by completing the following steps:

  1. Delete the contents in your S3 buckets (eip-analyzer-eipsnapshot-* and eip-analyzer-athenaresulteipanalyzer-*).
  2. Delete the S3 buckets.
  3. On the AWS CloudFormation console, delete the stack you created.

Conclusion

This post demonstrated how you can analyze Elastic IP usage history to have a better insight of EIP attachment patterns using Athena and CloudTrail. Check out the GitHub repo to regularly run this analysis as part of your cost-optimization strategy to identify and release inactive EIPs to reduce costs.

You can also use Athena to analyze logs from other AWS services; for more information, see Querying AWS service logs.

Additionally, you can analyze activity logs with AWS CloudTrail Lake and Amazon Athena. AWS CloudTrail Lake is a managed data lake that enables organizations to aggregate, immutably store, and query events recorded by CloudTrail for auditing, security investigation, and operational troubleshooting. AWS CloudTrail Lake supports the collection of events from multiple AWS regions and AWS accounts. For CloudTrail Lake, you pay for data ingestion, retention, and analysis. Refer to AWS CloudTrail Lake pricing page for pricing details.


About the Author

Aidin Khosrowshahi is a Senior Technical Account Manager with Amazon Web Services based out of San Francisco. He focuses on reliability, optimization, and improving operational mechanisms with his customers.

Source: https://aws.amazon.com/blogs/big-data/analyze-elastic-ip-usage-history-using-amazon-athena-and-aws-cloudtrail/