Amazon Elastic Compute Cloud (Amazon EC2) provides scalable computing capacity in the Amazon Web Services (AWS) Cloud. Using Amazon EC2 eliminates your need to invest in hardware up front, so you can develop and deploy applications faster.
You can use tagging to categorize your AWS resources in different ways. EC2 instance tagging is useful when you have many resources in your account and you want to quickly identify a specific resource based on the tags. You can assign custom metadata to your EC2 instances by using tags. A tag consists of a user-defined key and value. We recommend that you create a consistent set of tags to meet your organization's requirements.
This pattern provides an AWS CloudFormation template to help you monitor EC2 instances for specific tags. The template creates an Amazon CloudWatch Events event that watches for the AWS CloudTrail TagResource or UntagResource events, to detect new EC2 instance tagging or tag removal. If a predefined tag is missing, it calls an AWS Lambda function, which sends out a violation message to an email address that you provide, by using Amazon Simple Notification Service (Amazon SNS).
