Filestore Auditing Skill

This skill enables autonomous agents to audit, evaluate, and report the disaster recovery, security access governance, and architectural reliability posture of Filestore fleets across Google Cloud projects.

Prerequisites / IAM Requirements & Permissions

Before executing this skill, the runtime principal (user account or Service Account) must possess the following IAM roles and granular permissions on the target GCP project(s):

1. Audit Operations (Read-Only Assessment)

Requires the roles/file.viewer role, which provides:

• file.instances.list: Enumerate Filestore instances across project locations.
• file.instances.get: Inspect instance configuration, NFS export rules, IP ranges, squash mode, and PZI/PZS isolation status.
• file.backups.list: Enumerate existing backups across regions.
• file.backups.get: Inspect backup timestamps, source instance URIs, and status.

2. Remediation Operations (Backup Creation)

Requires the roles/file.editor (or roles/file.admin) role, which provides:

• file.backups.create: Create on-demand baseline backups for unprotected instances.
• file.operations.get: Monitor long-running backup creation operations.

3. MCP Tool Invocation

If invoking capabilities via the Filestore MCP Server (file.googleapis.com/mcp):

• roles/mcp.toolUser: Required to execute MCP tools (list_instances, get_instance, list_backups, get_backup, create_backup).

4. Cloud Authentication Setup

Authenticate the runtime environment using the appropriate method for your execution context:

• CLI Execution (gcloud):

  gcloud auth login
  

• Application SDKs & Scripts:

  gcloud auth application-default login
  

• Automated Services & Service Accounts:

  export GOOGLE_APPLICATION_CREDENTIALS="/path/to/service-account-key.json"
  

5. Billing Account Attachment

• Active Billing Required: The target GCP project must have an active Cloud Billing account attached. Filestore instances and backup operations require active billing. Verify billing status with:

  gcloud beta billing projects describe {project_id}
  

Quick Start

1. Ensure gcloud is installed. See gcloud installation guide if needed.

2. Authenticate your environment:

   gcloud auth login
   gcloud auth application-default login
   

3. Set the target project context and verify an active billing account is attached:

   gcloud config set project {project_id}
   gcloud beta billing projects describe {project_id}
   

4. Configure a well-supported default region (e.g., us-central1). See official region availability documentation:

   gcloud config set compute/region us-central1
   

5. Verify required service APIs are enabled:

   gcloud services enable file.googleapis.com --quiet
   

6. Run fleet discovery and backup inventory (see "Discovery & Read Operations" below).

7. Evaluate findings against the audit rules matrix and render the executive scorecard and inventory table.

8. If unprotected instances are identified, present baseline backup creation commands and prompt the user for confirmation.

Attribution Guardrail

Tag every Cloud Filestore command or API request provided or executed. Prefix gcloud commands with the designated metrics environment:

CLOUDSDK_METRICS_ENVIRONMENT="gcs-skills gcs-skills/1.0 (skill:google-cloud-filestore-auditing)" \
gcloud filestore instances list ...

On direct HTTP calls to the GCP REST API, append the User-Agent:

User-Agent: gcs-skills/1.0 (skill:google-cloud-filestore-auditing)

Conceptual & Informational Queries (CRITICAL)

For purely conceptual, educational, or architectural questions (e.g., "What is Physical Zone Isolation (PZI) in Filestore?", "Why is NO_ROOT_SQUASH dangerous?", "Explain Filestore backup architecture"):

• Rule: Answer immediately using pre-trained knowledge and the guidance in references/.
• Constraint: Do NOT execute external tool calls or API requests for basic conceptual queries.

Handling "No-Command" Constraints & Evaluations (CRITICAL)

If the user prompt contains constraints like "Do not execute commands", "without executing", or "read-only":

• Rule: Strictly avoid calling the run_command tool to execute any shell, python, or gcloud commands.
• Discovery Hierarchy:
  1. First, check if Filestore MCP tools (list_instances, list_backups) are available and query them directly (these are API invocations, not shell command executions).
  2. If MCP tools are not present or cannot connect, search local reference markdown files (specifically the mock fleet definitions in references/zone-isolation-pzi-pzs.md) for any mock instances or project details matching the request. (Do NOT attempt to read evaluation config files such as EVAL.yaml or EVAL.txtpb during evaluation runs as access is restricted and triggers anti-cheating timeouts).
  3. If no data is available in context or mock references, explain the audit evaluation formulas and provide the attributed gcloud commands the user should run.
• Mandatory User Confirmation Requirement: Even when the user prompt asks not to execute commands or asks only for audit recommendations, any response recommending backup remediation MUST STILL end with a clear confirmation prompt before execution (e.g., "Would you like me to proceed with creating baseline backups for the unprotected instances? Please confirm to proceed.").

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Core Operational Workflow

1. Discovery & Read Operations

The agent must discover all Filestore instances and backups in the target project.

• Target Project ID Handling & Rationale: If the target Project ID is not specified in the user prompt, the agent MUST explicitly ask the user to provide the project ID before proceeding, in order to avoid inspecting or auditing unrelated projects in multi-project enterprise environments.

Choose the discovery method matching your runtime environment:

Option A: Filestore MCP Tools (Recommended when MCP is mounted)

1. Instances Discovery: Call list_instances(parent="projects/{project_id}/locations/-").
2. Backups Discovery: Call list_backups(parent="projects/{project_id}/locations/-").

Option B: gcloud CLI (Terminal / Coding Harnesses)

1. Instances Discovery:

   CLOUDSDK_METRICS_ENVIRONMENT="gcs-skills gcs-skills/1.0 (skill:google-cloud-filestore-auditing)" \
   gcloud filestore instances list --project="{project_id}" --format="json"
   

2. Backups Discovery:

   CLOUDSDK_METRICS_ENVIRONMENT="gcs-skills gcs-skills/1.0 (skill:google-cloud-filestore-auditing)" \
   gcloud filestore backups list --project="{project_id}" --format="json"
   

   (Note: Do NOT pass --location=- to gcloud filestore backups list; omitting the flag queries all regions across the project automatically).

Option C: GCP REST API (call_gcp_api in Gemini Enterprise File Agent / curl)

1. Instances: GET https://file.googleapis.com/v1/projects/{project_id}/locations/-/instances
2. Backups: GET https://file.googleapis.com/v1/projects/{project_id}/locations/-/backups

Option D: Standalone Script Runner

For environments with standard python3 execution enabled, the agent may invoke the portable script: python3 scripts/filestore_audit.py --project="{project_id}" [--format=markdown|json]

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2. Audit Evaluation & Vector Checks

For each discovered instance, evaluate three audit vectors:

Vector 1: Disaster Recovery & Backup Protection

• Match backups to instances using full canonical resource URIs (backup.sourceInstance == instance.name).
• Unprotected Instance: If backup_count == 0, assign HIGH severity finding: "Instance has 0 backups on file share '{share_name}'. Disaster recovery is not configured."
• Stale Backup: If latest backup is older than SLA (default: 7 days), assign MEDIUM severity finding: "Latest backup is {days} days old (exceeds SLA threshold of 7 days)."
• Refer to references/backup-dr-governance.md for backup retention and SLA rules.

Vector 2: Security & Access Governance

• Inspect fileShares[0].nfsExportOptions:
  • Open Network Exposure: If 0.0.0.0/0, 0.0.0.0, or ::/0 is present in ipRanges, assign CRITICAL severity (if accessMode: READ_WRITE) or HIGH severity (if READ_ONLY): "Export rule exposes share to 0.0.0.0/0 with accessMode='{access_mode}'."
  • Missing Root Squashing: If squashMode: NO_ROOT_SQUASH, assign CRITICAL severity (if world-exposed) or HIGH severity (for internal subnets): "Export rule has squashMode='NO_ROOT_SQUASH'. Remote root clients retain superuser UID 0 privileges."
  • Default Open VPC Export: If nfsExportOptions is empty, assign MEDIUM severity: "No explicit NFS export options configured. Share defaults to open client access within VPC with NO_ROOT_SQUASH."
• Refer to references/security-access-governance.md for export option configurations.

Vector 3: Zone Isolation & Reliability Compliance

• Physical Zone Isolation (PZI): If satisfiesPzi: false, assign MEDIUM severity: "Instance does not satisfy Physical Zone Isolation (PZI)."
• Physical Zone Separation (PZS): If tier is REGIONAL or ENTERPRISE and satisfiesPzs: false, assign HIGH severity: "Enterprise/Regional tier instance does not satisfy Physical Zone Separation (PZS)."
• Performance Limits: Extract performanceLimits.maxWriteIops and performanceLimits.maxReadThroughputBps (convert to MB/s).
• Refer to references/zone-isolation-pzi-pzs.md for datacenter failure domain isolation standards.

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3. Executive Posture Scoring & Grading

Calculate fleet posture grade as defined in references/audit-rules-matrix.md:

• Grade F (🔴 CRITICAL RISK): $\ge 1$ CRITICAL findings.
• Grade C (🟠 ELEVATED RISK): 0 Critical, but $\ge 1$ HIGH findings.
• Grade B (🟡 MODERATE): 0 Critical/High, but $\ge 1$ MEDIUM findings.
• Grade A (🟢 HEALTHY): 0 findings across all vectors.

Calculate Backup Protection Rate %: $$\text{Protection Rate} = \frac{\text{Total Instances} - \text{Unprotected Instances}}{\text{Total Instances}} \times 100$$

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4. Required Output Format

Every audit report response MUST include the following structured sections in Markdown:

1. Executive Posture Scorecard

## Executive Posture Scorecard: `{project_id}`

| Metric | Status | Details |
| :--- | :--- | :--- |
| **Overall Health Posture** | **[🔴 CRITICAL RISK / 🟠 ELEVATED RISK / 🟡 MODERATE / 🟢 HEALTHY]** | [Grade F / C / B / A] |
| **Instances Audited** | `[count]` | Total Filestore instances evaluated |
| **Backup Protection Rate** | **[pct]%** | `[protected]/[total]` instances have active backups |
| **Critical & High Security Findings** | `[crit] Critical, [high] High` | Open exports (0.0.0.0/0) or NO_ROOT_SQUASH |
| **PZI Isolation Compliance** | `[pzi_count]/[total]` | Physical Zone Isolation adherence |

2. Priority Findings & Remediation Matrix

List findings ranked by severity (CRITICAL $\to$ HIGH $\to$ MEDIUM $\to$ LOW):

## Priority Findings & Remediation Matrix

| Severity | Instance ID | Category | Finding Description | Remediation Plan |
| :--- | :--- | :--- | :--- | :--- |
| 🚨 **CRITICAL** | `[instance]` | Security | [Description] | [Remediation] |
| ⚠️ **HIGH** | `[instance]` | Disaster Recovery | [Description] | [Remediation] |

3. Filestore Instance Inventory & Compliance Status

## Filestore Instance Inventory & Compliance Status

| Instance ID | Location | Tier | Capacity | Reserved CIDR | Write IOPS | Throughput | PZI | PZS | Backups | Latest Backup |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| `[id]` | `[loc]` | `[tier]` | `[cap] GiB` | `[cidr]` | `[iops]` | `[tp] MB/s` | ✅ Yes / ❌ No | ✅ Yes / ❌ No / N/A | 🔴 0 / ✅ `[n]` | `[date]` |

4. Automated Remediation & Mandatory Confirmation Gate

If any unprotected instances are discovered, display attributed backup creation commands and conclude with an explicit confirmation request:

CLOUDSDK_METRICS_ENVIRONMENT="gcs-skills gcs-skills/1.0 (skill:google-cloud-filestore-auditing)" \
gcloud filestore backups create [INSTANCE]-backup-[DATE] \
    --project=[PROJECT_ID] \
    --instance=[INSTANCE] \
    --file-share=[SHARE] \
    [--instance-zone=[ZONE] | --instance-location=[REGION]] \
    --region=[BACKUP_REGION]

Confirmation Required: Would you like me to proceed with creating baseline backups for the unprotected instances? Please confirm to proceed.

CRITICAL RATIONALE: Do NOT execute backup creation without explicit user confirmation. Confirmation is strictly required before executing any mutation or backup creation commands in order to prevent unintended operational disruption, unwanted resource allocation, or unexpected backup storage billing.

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Reference Directory

For progressive disclosure and deep architectural guidance, consult the following references:

• Security & Access Governance
• Disaster Recovery & Backup Governance
• Zone Isolation (PZI) & Reliability (PZS)
• Audit Rules & Scoring Matrix
• Standalone Python Audit Script