Delete Idle Image

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Prerequisite: To use this check, you must set up a GCP Recommender connection.

CloudZero has identified Google Compute Engine custom images that appear to be idle and safe candidates for cleanup. Unused custom images can incur ongoing storage costs, so deleting them can reduce spend with low operational risk when validated.

Google's Recommender (google.compute.image.IdleResourceRecommender, Sub-Type: DELETE_IMAGE) flags idle custom images using utilization and age signals. Treat these as starting points and confirm ownership and dependencies before deleting.

Recommendations

• Verify the image is truly unused - Confirm it is not referenced in instance templates, used by any active instances, or required for disaster recovery or future deployments.
• Check dependencies before deletion - Review instance templates, managed instance groups, and any automation or documentation that may reference the image.
• Validate ownership/intent - Confirm the image is not reserved for upcoming migrations, rollbacks, or compliance requirements; coordinate with service owners (especially for prod).
• Review image lineage - If the image was created from a snapshot or another image, ensure deletion won't impact related resources or recovery workflows.
• Delete safely - Prefer non-prod validation first, schedule changes during maintenance windows, and monitor after deletion.
• Understand recovery limitations - Once deleted, the same image cannot be recovered; plan updates to any references accordingly and ensure backups exist if needed.

Note: For how to view, apply, or manage these recommendations in Google Cloud, refer to Google's official documentation on deleting idle custom images.