Configure Authorization Policy Dry Run Logging

What Dry-Run Authorization Policy Mode Is

Dry-run mode is an advanced policy evaluation mechanism in Cloud Service Mesh and Kubernetes authorization frameworks that allows security policies to be evaluated against real, live production traffic without applying active blocking enforcement. By attaching the "istio.io/dry-run": "true" annotation to the AuthorizationPolicy custom resource metadata, the mesh control plane instructs sidecar proxies to calculate policy decisions while permitting all requests to proceed.

How It Meets the Security and Testing Requirements

• Non-blocking verification: Setting "istio.io/dry-run": "true" ensures that the proxy evaluates every request against configured rules, allowing administrators to understand the potential impact before enforcing strict denials.
• Audit visibility: Cloud Service Mesh automatically emits evaluation metadata to Cloud Logging (such as dry_run_result, dry_run_policy_name, and dry_run_policy_rule).
• Targeted violation filtering: Filtering for labels.dry_run_result="AuthzDenied" in Logs Explorer directly isolates requests that would have been rejected under active enforcement.

Key Advantages and Capabilities

• Production-safe rollout: Validates complex authorization and path-matching rules against real-world user patterns without inducing service downtime.
• Granular policy tracing: Captures the exact policy name and rule index that triggered the simulated denial for rapid troubleshooting.
• Structured audit integration: Direct integration with Cloud Logging and Cloud Audit Logs provides telemetry for compliance verification.
• Seamless transition: Switching from dry-run to blocking enforcement requires only removing the dry-run annotation once validation is complete.

Why This Is Optimal

Using native dry-run mode eliminates the risk of accidental production outages during security policy onboarding while generating exact audit logs of policy evaluation behavior.