AWS EC2 get notified when a tag changes

Question

I want to call a lambda function when my EC2 tag "Something" changes. Is it possible? If I cannot listen to changes to a specific tag, I could listen on EC2 config changes. How can I do that? I am not sure which option to select on cloudwatch events ...

UPDATE

I tried AWS Config, but it appears that it only monitors config changes when instance is started?

Answer 1

Yes, you can use Amazon CloudWatch Events with AWS CloudTrail to call a Lambda function, triggered off a CreateTags event. (Changing a tag is actually treated as creating a tag.)

• Turn on AWS CloudTrail for your region (this involves pointing it to an Amazon S3 bucket for log storage)
• Create an Amazon SNS topic
• Create an AWS Lambda function with a trigger on the SNS topic
• Create an Amazon CloudWatch Events rule:
  • Service Name: EC2
  • Event Type: AWS API Call via CloudTrail
  • Specific Operations: CreateTags
  • Add Target: Select your Lambda function

Your Lambda function will receive a notification when a tag is created/changed.