Cloudflare Development Best Practices

Overview

This skill provides comprehensive guidelines for developing applications on Cloudflare's edge platform, including Workers, Pages, KV storage, D1 databases, R2 object storage, and Durable Objects.

Core Principles

Write lightweight, fast code optimized for edge execution
Minimize cold start times and execution duration
Use appropriate storage solutions for each use case
Follow security best practices for edge computing
Leverage Cloudflare's global network for performance

Cloudflare Workers Guidelines

Basic Worker Structure

typescript

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
    try {
      const url = new URL(request.url);

      // Route handling
      if (url.pathname === '/api/data') {
        return handleApiRequest(request, env);
      }

      return new Response('Not Found', { status: 404 });
    } catch (error) {
      console.error('Worker error:', error);
      return new Response('Internal Server Error', { status: 500 });
    }
  },
} satisfies ExportedHandler<Env>;

Environment Types

typescript

interface Env {
  // KV Namespaces
  MY_KV: KVNamespace;

  // D1 Databases
  MY_DB: D1Database;

  // R2 Buckets
  MY_BUCKET: R2Bucket;

  // Durable Objects
  MY_DURABLE_OBJECT: DurableObjectNamespace;

  // Environment Variables
  API_KEY: string;
}

Best Practices

Use TypeScript for type safety
Handle errors at the edge appropriately
Implement proper request validation
Use
```
ctx.waitUntil()
```
for background tasks
Minimize external API calls when possible

Wrangler Configuration

wrangler.toml Structure

toml

name = "my-worker"
main = "src/index.ts"
compatibility_date = "2024-01-01"

[vars]
ENVIRONMENT = "production"

[[kv_namespaces]]
binding = "MY_KV"
id = "abc123"

[[d1_databases]]
binding = "MY_DB"
database_name = "my-database"
database_id = "def456"

[[r2_buckets]]
binding = "MY_BUCKET"
bucket_name = "my-bucket"

[durable_objects]
bindings = [
  { name = "MY_DURABLE_OBJECT", class_name = "MyDurableObject" }
]

[[migrations]]
tag = "v1"
new_classes = ["MyDurableObject"]

KV Storage Guidelines

Usage Patterns

typescript

// Writing to KV
await env.MY_KV.put('key', JSON.stringify(data), {
  expirationTtl: 3600, // 1 hour
  metadata: { version: '1.0' },
});

// Reading from KV
const value = await env.MY_KV.get('key', { type: 'json' });

// Listing keys
const list = await env.MY_KV.list({ prefix: 'user:' });

Best Practices

Use KV for read-heavy workloads with eventual consistency
Set appropriate TTLs for cached data
Use metadata for additional key information
Implement cache invalidation strategies
Be aware of KV's eventual consistency model

D1 Database Guidelines

Query Patterns

typescript

// Parameterized queries (prevent SQL injection)
const results = await env.MY_DB
  .prepare('SELECT * FROM users WHERE id = ?')
  .bind(userId)
  .all();

// Batch operations
const batch = await env.MY_DB.batch([
  env.MY_DB.prepare('INSERT INTO logs (message) VALUES (?)').bind('log1'),
  env.MY_DB.prepare('INSERT INTO logs (message) VALUES (?)').bind('log2'),
]);

// First result only
const user = await env.MY_DB
  .prepare('SELECT * FROM users WHERE email = ?')
  .bind(email)
  .first();

Schema Management

sql

-- migrations/0001_initial.sql
CREATE TABLE users (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  email TEXT UNIQUE NOT NULL,
  name TEXT NOT NULL,
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_users_email ON users(email);

Best Practices

Always use parameterized queries
Create appropriate indexes
Use batch operations for multiple writes
Keep queries simple and efficient
Use migrations for schema changes

R2 Object Storage Guidelines

Usage Patterns

typescript

// Upload object
await env.MY_BUCKET.put('uploads/file.pdf', fileData, {
  httpMetadata: {
    contentType: 'application/pdf',
  },
  customMetadata: {
    uploadedBy: userId,
  },
});

// Download object
const object = await env.MY_BUCKET.get('uploads/file.pdf');
if (object) {
  return new Response(object.body, {
    headers: {
      'Content-Type': object.httpMetadata?.contentType || 'application/octet-stream',
    },
  });
}

// List objects
const list = await env.MY_BUCKET.list({ prefix: 'uploads/' });

// Delete object
await env.MY_BUCKET.delete('uploads/file.pdf');

Best Practices

Set appropriate content types
Use multipart uploads for large files
Implement proper access controls
Use presigned URLs for direct client uploads
Organize objects with logical prefixes

Durable Objects Guidelines

Implementation

typescript

export class ChatRoom implements DurableObject {
  private state: DurableObjectState;
  private sessions: Map<WebSocket, { id: string }>;

  constructor(state: DurableObjectState, env: Env) {
    this.state = state;
    this.sessions = new Map();
  }

  async fetch(request: Request): Promise<Response> {
    const url = new URL(request.url);

    if (url.pathname === '/websocket') {
      const pair = new WebSocketPair();
      await this.handleSession(pair[1]);
      return new Response(null, { status: 101, webSocket: pair[0] });
    }

    return new Response('Not Found', { status: 404 });
  }

  async handleSession(webSocket: WebSocket) {
    webSocket.accept();

    webSocket.addEventListener('message', async (event) => {
      // Handle messages
    });

    webSocket.addEventListener('close', () => {
      this.sessions.delete(webSocket);
    });
  }
}

Best Practices

Use for coordination and stateful logic
Implement proper WebSocket handling
Use storage API for persistence
Handle hibernation for cost optimization
Design for single-point-of-coordination patterns

Cloudflare Pages Guidelines

Project Structure

my-pages-project/
├── public/           # Static assets
├── functions/        # Pages Functions
│   ├── api/
│   │   └── [endpoint].ts
│   └── _middleware.ts
├── src/              # Application source
└── wrangler.toml     # Configuration

Pages Functions

typescript

// functions/api/users.ts
export const onRequestGet: PagesFunction<Env> = async (context) => {
  const users = await context.env.MY_DB
    .prepare('SELECT * FROM users')
    .all();

  return Response.json(users.results);
};

export const onRequestPost: PagesFunction<Env> = async (context) => {
  const body = await context.request.json();
  // Handle POST
  return Response.json({ success: true });
};

Edge Security Best Practices

Request Validation

typescript

function validateRequest(request: Request): boolean {
  // Check content type
  const contentType = request.headers.get('Content-Type');
  if (request.method === 'POST' && !contentType?.includes('application/json')) {
    return false;
  }

  // Check origin (CORS)
  const origin = request.headers.get('Origin');
  if (origin && !ALLOWED_ORIGINS.includes(origin)) {
    return false;
  }

  return true;
}

Authentication

typescript

async function verifyAuth(request: Request, env: Env): Promise<boolean> {
  const authHeader = request.headers.get('Authorization');
  if (!authHeader?.startsWith('Bearer ')) {
    return false;
  }

  const token = authHeader.slice(7);
  // Verify JWT or API key
  return await verifyToken(token, env);
}

Rate Limiting

typescript

async function checkRateLimit(ip: string, env: Env): Promise<boolean> {
  const key = `ratelimit:${ip}`;
  const current = await env.MY_KV.get(key, { type: 'json' }) as number || 0;

  if (current >= 100) { // 100 requests per window
    return false;
  }

  await env.MY_KV.put(key, JSON.stringify(current + 1), {
    expirationTtl: 60, // 1 minute window
  });

  return true;
}

Performance Optimization

Caching Strategies

typescript

// Cache API usage
const cache = caches.default;

async function handleRequest(request: Request): Promise<Response> {
  // Check cache
  const cached = await cache.match(request);
  if (cached) {
    return cached;
  }

  // Generate response
  const response = await generateResponse(request);

  // Cache response
  const cacheResponse = new Response(response.body, response);
  cacheResponse.headers.set('Cache-Control', 'public, max-age=3600');
  ctx.waitUntil(cache.put(request, cacheResponse.clone()));

  return cacheResponse;
}

Background Processing

typescript

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
    // Respond immediately
    const response = Response.json({ status: 'accepted' });

    // Process in background
    ctx.waitUntil(processInBackground(request, env));

    return response;
  },
};

Testing

Local Development

bash

# Start local development server
wrangler dev

# Run with local persistence
wrangler dev --persist

# Test with specific environment
wrangler dev --env staging

Unit Testing

typescript

import { unstable_dev } from 'wrangler';

describe('Worker', () => {
  let worker: UnstableDevWorker;

  beforeAll(async () => {
    worker = await unstable_dev('src/index.ts', {
      experimental: { disableExperimentalWarning: true },
    });
  });

  afterAll(async () => {
    await worker.stop();
  });

  test('returns 200 for valid request', async () => {
    const response = await worker.fetch('/api/health');
    expect(response.status).toBe(200);
  });
});

Deployment

Production Deployment

bash

# Deploy to production
wrangler deploy

# Deploy to specific environment
wrangler deploy --env production

# Deploy with secrets
wrangler secret put API_KEY

CI/CD Integration

yaml

# .github/workflows/deploy.yml
name: Deploy Worker

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: cloudflare/wrangler-action@v3
        with:
          apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}

Common Pitfalls to Avoid

Not handling errors at the edge properly
Making too many external API calls
Ignoring Worker CPU and memory limits
Not using appropriate storage for use case
Forgetting eventual consistency in KV
Not implementing proper rate limiting
Hardcoding secrets in code
Ignoring cold start optimization

cloudflare-development

NPX Install

Tags

SKILL.md Content

Cloudflare Development Best Practices

Overview

Core Principles

Cloudflare Workers Guidelines

Basic Worker Structure

Environment Types

Best Practices

Wrangler Configuration

wrangler.toml Structure

KV Storage Guidelines

Usage Patterns

Best Practices

D1 Database Guidelines

Query Patterns

Schema Management

Best Practices

R2 Object Storage Guidelines

Usage Patterns

Best Practices

Durable Objects Guidelines

Implementation

Best Practices

Cloudflare Pages Guidelines

Project Structure

Pages Functions

Edge Security Best Practices

Request Validation

Authentication

Rate Limiting

Performance Optimization

Caching Strategies

Background Processing

Testing

Local Development

Unit Testing

Deployment

Production Deployment

CI/CD Integration

Common Pitfalls to Avoid