Vercel Migration Deep Dive

Overview

Comprehensive guide for migrating to or from Vercel, or major version upgrades.

Prerequisites

Current system documentation
Vercel SDK installed
Feature flag infrastructure
Rollback strategy tested

Migration Types

Type	Complexity	Duration	Risk
Fresh install	Low	Days	Low
From competitor	Medium	Weeks	Medium
Major version	Medium	Weeks	Medium
Full replatform	High	Months	High

Pre-Migration Assessment

Step 1: Current State Analysis

# Document current implementation
find . -name "*.ts" -o -name "*.py" | xargs grep -l "vercel" > vercel-files.txt

# Count integration points
wc -l vercel-files.txt

# Identify dependencies
npm list | grep vercel
pip freeze | grep vercel

Step 2: Data Inventory

interface MigrationInventory {
  dataTypes: string[];
  recordCounts: Record<string, number>;
  dependencies: string[];
  integrationPoints: string[];
  customizations: string[];
}

async function assessVercelMigration(): Promise<MigrationInventory> {
  return {
    dataTypes: await getDataTypes(),
    recordCounts: await getRecordCounts(),
    dependencies: await analyzeDependencies(),
    integrationPoints: await findIntegrationPoints(),
    customizations: await documentCustomizations(),
  };
}

Migration Strategy: Strangler Fig Pattern

Phase 1: Parallel Run
┌─────────────┐     ┌─────────────┐
│   Old       │     │   New       │
│   System    │ ──▶ │  Vercel   │
│   (100%)    │     │   (0%)      │
└─────────────┘     └─────────────┘

Phase 2: Gradual Shift
┌─────────────┐     ┌─────────────┐
│   Old       │     │   New       │
│   (50%)     │ ──▶ │   (50%)     │
└─────────────┘     └─────────────┘

Phase 3: Complete
┌─────────────┐     ┌─────────────┐
│   Old       │     │   New       │
│   (0%)      │ ──▶ │   (100%)    │
└─────────────┘     └─────────────┘

Implementation Plan

Phase 1: Setup (Week 1-2)

# Install Vercel SDK
npm install vercel

# Configure credentials
cp .env.example .env.vercel
# Edit with new credentials

# Verify connectivity
node -e "require('vercel').ping()"

Phase 2: Adapter Layer (Week 3-4)

// src/adapters/vercel.ts
interface ServiceAdapter {
  create(data: CreateInput): Promise<Resource>;
  read(id: string): Promise<Resource>;
  update(id: string, data: UpdateInput): Promise<Resource>;
  delete(id: string): Promise<void>;
}

class VercelAdapter implements ServiceAdapter {
  async create(data: CreateInput): Promise<Resource> {
    const vercelData = this.transform(data);
    return vercelClient.create(vercelData);
  }

  private transform(data: CreateInput): VercelInput {
    // Map from old format to Vercel format
  }
}

Phase 3: Data Migration (Week 5-6)

async function migrateVercelData(): Promise<MigrationResult> {
  const batchSize = 100;
  let processed = 0;
  let errors: MigrationError[] = [];

  for await (const batch of oldSystem.iterateBatches(batchSize)) {
    try {
      const transformed = batch.map(transform);
      await vercelClient.batchCreate(transformed);
      processed += batch.length;
    } catch (error) {
      errors.push({ batch, error });
    }

    // Progress update
    console.log(`Migrated ${processed} records`);
  }

  return { processed, errors };
}

Phase 4: Traffic Shift (Week 7-8)

// Feature flag controlled traffic split
function getServiceAdapter(): ServiceAdapter {
  const vercelPercentage = getFeatureFlag('vercel_migration_percentage');

  if (Math.random() * 100 < vercelPercentage) {
    return new VercelAdapter();
  }

  return new LegacyAdapter();
}

Rollback Plan

# Immediate rollback
kubectl set env deployment/app VERCEL_ENABLED=false
kubectl rollout restart deployment/app

# Data rollback (if needed)
./scripts/restore-from-backup.sh --date YYYY-MM-DD

# Verify rollback
curl https://app.yourcompany.com/health | jq '.services.vercel'

Post-Migration Validation

async function validateVercelMigration(): Promise<ValidationReport> {
  const checks = [
    { name: 'Data count match', fn: checkDataCounts },
    { name: 'API functionality', fn: checkApiFunctionality },
    { name: 'Performance baseline', fn: checkPerformance },
    { name: 'Error rates', fn: checkErrorRates },
  ];

  const results = await Promise.all(
    checks.map(async c => ({ name: c.name, result: await c.fn() }))
  );

  return { checks: results, passed: results.every(r => r.result.success) };
}

Instructions

Step 1: Assess Current State

Document existing implementation and data inventory.

Step 2: Build Adapter Layer

Create abstraction layer for gradual migration.

Step 3: Migrate Data

Run batch data migration with error handling.

Step 4: Shift Traffic

Gradually route traffic to new Vercel integration.

Output

Migration assessment complete
Adapter layer implemented
Data migrated successfully
Traffic fully shifted to Vercel

Error Handling

Issue	Cause	Solution
Data mismatch	Transform errors	Validate transform logic
Performance drop	No caching	Add caching layer
Rollback triggered	Errors spiked	Reduce traffic percentage
Validation failed	Missing data	Check batch processing

Examples

Quick Migration Status

const status = await validateVercelMigration();
console.log(`Migration ${status.passed ? 'PASSED' : 'FAILED'}`);
status.checks.forEach(c => console.log(`  ${c.name}: ${c.result.success}`));

Resources

Flagship+ Skills

For advanced troubleshooting, see vercel-advanced-troubleshooting.

vercel-migration-deep-dive