vercel-data-handlingClaude Skill

Vercel Data Handling

Overview

Handle sensitive data correctly on Vercel: PII redaction in logs, GDPR-compliant data processing in serverless functions, secure cookie management, and data residency configuration. Covers both what Vercel stores and what your application should protect.

Prerequisites

• Understanding of GDPR/CCPA requirements
• Vercel Pro or Enterprise (for data residency options)
• Logging infrastructure with PII awareness

Instructions

Step 1: Understand What Vercel Stores

Data Type	Where	Retention	Control
Runtime logs	Vercel servers	1hr (free), 30d (Plus)	Log drains
Build logs	Vercel servers	30 days	Automatic
Analytics data	Vercel	Aggregated, no PII	Disable in dashboard
Deployment source	Vercel	Until deleted	Manual deletion
Environment variables	Vercel (encrypted)	Until deleted	Scoped access

Step 2: PII Redaction in Logs

// lib/redact.ts — redact PII before logging
const PII_PATTERNS: [RegExp, string][] = [
  [/\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b/g, '[EMAIL]'],
  [/\b\d{3}[-.]?\d{3}[-.]?\d{4}\b/g, '[PHONE]'],
  [/\b\d{3}-\d{2}-\d{4}\b/g, '[SSN]'],
  [/\b\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}\b/g, '[CARD]'],
  [/\b(?:Bearer|token|key|secret|password)\s*[:=]\s*\S+/gi, '[CREDENTIAL]'],
];

export function redact(text: string): string {
  let result = text;
  for (const [pattern, replacement] of PII_PATTERNS) {
    result = result.replace(pattern, replacement);
  }
  return result;
}

// Usage — always redact before console.log
import { redact } from '@/lib/redact';

export async function POST(request: Request) {
  const body = await request.json();
  console.log('Request received:', redact(JSON.stringify(body)));
  // Process safely...
}

Step 3: GDPR-Compliant API Routes

// api/users/[id]/route.ts — data subject request handlers
import { NextRequest, NextResponse } from 'next/server';
import { db } from '@/lib/db';

// Right to Access (GDPR Art. 15)
export async function GET(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  const user = await db.user.findUnique({
    where: { id: params.id },
    include: { posts: true, preferences: true },
  });

  if (!user) return NextResponse.json({ error: 'Not found' }, { status: 404 });

  return NextResponse.json({
    personalData: {
      name: user.name,
      email: user.email,
      createdAt: user.createdAt,
      posts: user.posts,
      preferences: user.preferences,
    },
    exportedAt: new Date().toISOString(),
  });
}

// Right to Erasure (GDPR Art. 17)
export async function DELETE(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  // Soft delete — anonymize instead of hard delete for audit trail
  await db.user.update({
    where: { id: params.id },
    data: {
      email: `deleted-${params.id}@redacted.local`,
      name: '[DELETED]',
      deletedAt: new Date(),
    },
  });

  // Also delete from log drain provider if applicable
  console.log(`GDPR deletion completed for user ${params.id}`);
  return NextResponse.json({ deleted: true });
}

Step 4: Secure Cookie Management

// lib/cookies.ts — GDPR-aware cookie handling
import { cookies } from 'next/headers';

export function setSessionCookie(token: string): void {
  cookies().set('session', token, {
    httpOnly: true,       // Not accessible via JavaScript
    secure: true,         // HTTPS only
    sameSite: 'lax',      // CSRF protection
    maxAge: 60 * 60 * 24, // 24 hours
    path: '/',
  });
}

export function setConsentCookie(consent: Record<string, boolean>): void {
  cookies().set('consent', JSON.stringify(consent), {
    httpOnly: false,  // Needs client-side access
    secure: true,
    sameSite: 'lax',
    maxAge: 60 * 60 * 24 * 365, // 1 year
    path: '/',
  });
}

// Middleware — block analytics if consent not given
export function middleware(request: Request) {
  const consent = request.headers.get('cookie')?.includes('consent');
  if (!consent) {
    // Strip analytics query params, skip tracking middleware
  }
}

Step 5: Data Residency Configuration

Vercel allows configuring where your serverless functions execute:

// vercel.json — restrict function execution to EU regions
{
  "regions": ["cdg1", "lhr1"],
  "functions": {
    "api/**/*.ts": {
      "regions": ["cdg1"]
    }
  }
}

EU regions for GDPR data residency:

Region	Location	Code
Paris	France	cdg1
London	UK	lhr1
Frankfurt	Germany	fra1

Step 6: Audit Logging

// lib/audit-log.ts — track data access for compliance
interface AuditEntry {
  action: 'read' | 'create' | 'update' | 'delete' | 'export';
  resource: string;
  resourceId: string;
  userId: string;
  ip: string;
  timestamp: string;
}

export async function auditLog(entry: Omit<AuditEntry, 'timestamp'>): Promise<void> {
  const record: AuditEntry = {
    ...entry,
    timestamp: new Date().toISOString(),
  };

  // Write to database audit table
  await db.auditLog.create({ data: record });

  // Also log for log drain capture (structured JSON)
  console.log(JSON.stringify({ type: 'audit', ...record }));
}

// Usage in API route:
export async function GET(request: NextRequest) {
  await auditLog({
    action: 'read',
    resource: 'user',
    resourceId: params.id,
    userId: session.userId,
    ip: request.headers.get('x-forwarded-for') ?? 'unknown',
  });
}

Data Classification Guide

Category	Examples	Handling on Vercel
PII	Email, name, phone, IP	Redact from logs, encrypt at rest
Secrets	API keys, tokens, passwords	Use type: sensitive env vars, never log
Financial	Card numbers, bank info	Never process in functions — use Stripe/payment provider
Health	Medical records	Requires BAA — contact Vercel Enterprise
Business	Metrics, usage stats	Aggregate before logging

Output

• PII redaction applied to all log output
• GDPR data subject request endpoints implemented
• Secure cookie handling with consent management
• Data residency configured via function regions
• Audit logging for compliance trail

Error Handling

Error	Cause	Solution
PII in Vercel logs	Not redacting before console.log	Use redact() wrapper on all log calls
GDPR data request timeout	Large data export in function	Paginate or use background processing
Cookies not secure	Missing secure: true flag	Always set httpOnly and secure flags
Function running in wrong region	Region not set in vercel.json	Specify regions per function

Resources

• Vercel Privacy Policy
• Vercel Data Processing Agreement
• GDPR Overview
• Vercel Function Regions
• Vercel Security

Next Steps

For enterprise RBAC, see vercel-enterprise-rbac.