Running out of IP addresses in your subnets is a real issue that most teams face these days. Most of the times those IPs are reserved but unused!
This blog will address the problem of Unused Elastic Network Interfaces and what to do to free up our IP address Pool for other services.
The Solution will consist of a Lambda function that gets triggered daily and a CloudWatch Alarm to alert us of any errors generated by our Lambda.
At first I will go through the solution and how to create it using the AWS Console, then I will be doing the same solution but using Infrastructure as Code (Terraform).
Creating the Lambda
Before Going through the code, let’s set up some of the configuration parameters:
1- The most important one is the timeout, make sure that it is more than 1 minute (this will depend on your workloads)
2- Memory: 200 MB should be enough.
3- No need to put the lambda inside a VPC.
Lambda Code using python:
First, import AWS SDK for Python…