Binary Authorization Policy Attestor Kms Config

What Binary Authorization Attestation Architecture Is

Binary Authorization is a deploy-time security control for Google Kubernetes Engine (GKE) and Cloud Run that ensures only trusted container images are deployed. An attestor is a named Google Cloud resource that verifies cryptographic signatures (attestations) associated with a container image digest. The attestor links an Artifact Analysis note—which serves as the metadata anchor for storing attestation occurrences—to public keys or asymmetric Cloud Key Management Service (Cloud KMS) cryptographic keys used to verify those signatures.

How It Meets the Requirements

• Cloud KMS Asymmetric Keys & Artifact Analysis Note: Binary Authorization requires an Artifact Analysis note to store attestation metadata and uses asymmetric key pairs hosted in Cloud KMS (where the private key signs the image digest in CI/CD pipelines and the public verification key is bound to the attestor).
• Default Evaluation Rule: Setting the defaultAdmissionRule to REQUIRE_ATTESTATION with requireAttestationsBy: [projects/PROJECT_ID/attestors/prod-attestor] ensures all GKE and Cloud Run deployments enforce signature validation across standard workloads.
• Cluster-Specific Override: Adding a rule under clusterAdmissionRules for us-central1-a.staging-cluster with Dry Run Mode (DRYRUN_AUDIT_LOG_ONLY) evaluates the policy against incoming deployments and emits audit logs in Cloud Logging without rejecting unverified containers.
• GKE Cluster Enforcement: Deploying or updating clusters with --binauthz-evaluation-mode=PROJECT_SINGLETON_POLICY_ENFORCE activates the admission controller to query the project's singleton policy at deploy time.

Key Advantages

• Cryptographic Provenance: Eliminates unsigned or unapproved container deployments across both serverless (Cloud Run) and managed Kubernetes (GKE) runtimes.
• Centralized Key Management: Cloud KMS ensures asymmetric signing keys remain secure and auditable with native IAM controls.
• Safe Policy Rollouts: Dry Run mode allows platform engineers to test policy configurations in staging without interrupting development workflows.
• Hierarchical Policy Precedence: Cluster-specific admission rules take precedence over default admission rules, providing granular multi-environment governance.

Why This Is Optimal

This solution follows Google Cloud recommended security practices by leveraging built-in Artifact Analysis metadata management, Cloud KMS cryptographic key protection, and native project singleton policy evaluation flags on GKE.