[Feature Request] Out-of-Band Drift Alerting #46

Feature Description

Automated alerting triggered when infrastructure changes are made outside of the authorized Terraform CI/CD service account.

Use Case

To maintain strict compliance and security, administrators need to know immediately if a human operator makes manual edits (drift) in the Google Cloud Console.

Proposed Solution

Create a dedicated blueprint utilizing Google Cloud Log Router and Pub/Sub to filter for administrative write operations missing the Terraform service account identity, and route those events to an alerting topic.

Compliance & Deployment Context

• Target Deployment Type(s):
  • US Region Restricted (e.g., Access Policy constraint)
  • FedRAMP Medium
  • FedRAMP High
  • DoD IL4
  • DoD IL5
  • All / General
• Relevant NIST 800-53r5 Controls: AU-6 (Audit Record Review, Analysis, and Reporting), SI-4 (System Monitoring).

Reusability Check

Stellar Engine prioritizes reusability.

• I have checked if this functionality can be achieved by extending an existing module or blueprint.
• I have verified that this does not duplicate existing functionality.

Alternatives Considered

Relying strictly on Security Command Center, which does not provide immediate granular alerting for out-of-band IAM/Compute modifications.

Additional Context

This was explicitly requested in the legacy Feature Braindump from 2023.