Clean-up Unused AMIs

Opportunity Name:

Clean-up Unused AMIs

 

AWS Resource Type:

EC2 AMIs

 

Opportunity Description:

EBS-backed AMIs are based on EBS snapshots, which cost money to store in an AWS account. If an AMI hasn't recently been used, it can safely be deregistered. The underlying resources of that AMI (i.e., EBS snapshots) can then be archived or deleted by other fixers. This finder identifies AMIs that are potentially unused and could be deregistered to save costs.

 

Criteria for identifying the opportunity:

• AMI is not used by any running or stopped instances.
• AMI is not owned by Amazon.
• AMI is not created by AWS Backup service.
• AMI and its associated snapshots have not been used or launched in the last 31 days.
• Annual cost of the AMI's associated snapshot storage, extrapolated from the last 31 days of usage, exceeds your account's configured cost threshold (a system-wide setting shared across finders, not a value specific to this recommendation).

 

Potential savings (range in % on annual basis):

This fixer has no direct savings of its own. It unlocks savings from downstream fixers that can archive or delete the EBS snapshots that once belonged to the AMI — those snapshots can't be archived or deleted until the AMI is deregistered.

 

Can CloudFix apply an automatic fix?

Yes

 

What happens when the Fixer is executed?

The AMI is tagged with CloudFix-specific tags. An AWS Recycle Bin retention rule is created (based on those tags), which permits restoring the AMI within 31 days of deregistration. The AMI is then deregistered.

 

Is it possible to rollback once CloudFix implements the fixer?

Automated rollback is unavailable. The fixer can be rolled back manually by restoring the AMI from the AWS Recycle Bin within the 31-day retention window.

 

Does this fix require downtime?

No

 

Other considerations:

• Before deregistering an AMI, ensure that it is not required for future use or by other applications.
• Consider creating a manual snapshot of the AMI for backup purposes before deregistration.
• Review and understand the dependencies of the AMI. Deregistering an AMI will make it unavailable for launching new instances.
• Security concerns: Ensure that deregistering the AMI does not affect your application's compliance and security posture.

 

Additional Resources:

• CloudFix Knowledge Base
• Deregister Your AMI
• Deleting an Amazon EBS Snapshot
• AMI Recycle Bin