Cloudflare Workers — Serverless Ở Biên Toàn Cầu • blog.dopana

Cloudflare Workers chạy code ở 330+ datacenter trên toàn cầu — gần user nhất, không cold start, giá rẻ.

Workers vs Lambda#

	Cloudflare Workers	AWS Lambda
Runtime	V8 Isolates	Container
Cold start	~0ms (luôn warm)	~100-500ms
Regions	330+	Tự chọn region
Price	$0.30/million req	$0.20/million req + duration
Duration	30s CPU, 5min (fetch)	15 phút
Memory	128MB (free)	128MB-10GB

Hello World#

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
    return new Response('Hello from the edge!', {
      headers: {
        'Content-Type': 'text/plain',
        'x-edge-location': request.cf?.colo || 'unknown',
      },
    });
  },
};

typescript

Routing#

import { Router } from 'itty-router';

const router = Router();

router.get('/api/users', async (request) => {
  const users = await getUsers();
  return Response.json(users);
});

router.get('/api/users/:id', async (request) => {
  const { id } = request.params;
  const user = await getUser(id);
  if (!user) {
    return new Response('Not found', { status: 404 });
  }
  return Response.json(user);
});

router.post('/api/users', async (request) => {
  const body = await request.json();
  const user = await createUser(body);
  return Response.json(user, { status: 201 });
});

router.all('*', () => new Response('Not found', { status: 404 }));

export default {
  fetch: router.handle,
};

typescript

Storage — KV, R2, D1#

KV — Key-Value Store#

// wrangler.jsonc
{
  "kv_namespaces": [
    { "binding": "CACHE", "id": "abc123" }
  ]
}

typescript

// Read
const cached = await env.CACHE.get('user:123', 'json');
if (cached) return Response.json(cached);

// Write
const user = await fetchUser(123);
await env.CACHE.put('user:123', JSON.stringify(user), {
  expirationTtl: 3600, // 1 giờ
});

// List
const list = await env.CACHE.list({ prefix: 'user:', limit: 100 });

typescript

R2 — Object Storage (S3-compatible)#

const object = await env.BUCKET.get('images/avatar.jpg');
if (!object) return new Response('Not found', { status: 404 });

return new Response(object.body, {
  headers: {
    'Content-Type': object.httpMetadata?.contentType || 'image/jpeg',
    'Cache-Control': 'public, max-age=31536000',
  },
});

// Upload
await env.BUCKET.put('uploads/file.pdf', request.body, {
  httpMetadata: { contentType: 'application/pdf' },
});

typescript

D1 — SQLite Database#

// Schema
const db = env.DB;
await db.exec(`
  CREATE TABLE IF NOT EXISTS users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    email TEXT UNIQUE NOT NULL
  )
`);

// Query
const users = await db.prepare('SELECT * FROM users WHERE id = ?').bind(1).all();
const user = users.results[0];

// Prepared statement
const stmt = db.prepare('INSERT INTO users (name, email) VALUES (?1, ?2)');
await stmt.bind('Alice', 'alice@example.com').run();

typescript

Env — Environment Variables#

// wrangler.jsonc
{
  "vars": {
    "API_URL": "https://api.example.com",
    "LOG_LEVEL": "info"
  }
}

// TypeScript
interface Env {
  API_URL: string;
  LOG_LEVEL: string;
  CACHE: KVNamespace;
  DB: D1Database;
  BUCKET: R2Bucket;
  AI: Ai;
}

typescript

Cron Triggers#

export default {
  async scheduled(event: ScheduledEvent, env: Env, ctx: ExecutionContext) {
    switch (event.cron) {
      case '*/5 * * * *':
        await syncData(env);
        break;
      case '0 0 * * *':
        await cleanupOldRecords(env);
        break;
    }
  },
};

typescript

{
  "triggers": {
    "crons": ["*/5 * * * *", "0 0 * * *"]
  }
}

json

Workers AI#

Built-in AI inference at the edge:

async function translateText(text: string, env: Env) {
  const response = await env.AI.run('@cf/meta/m2m100-1.2b', {
    text,
    source_lang: 'vietnamese',
    target_lang: 'english',
  });
  return response;
}

async function generateImage(prompt: string, env: Env) {
  const response = await env.AI.run('@cf/stabilityai/stable-diffusion-xl-base-1.0', {
    prompt,
  });
  return new Response(response.image, {
    headers: { 'Content-Type': 'image/png' },
  });
}

typescript

Wrangler — CLI#

# Init
npm create cloudflare@latest my-worker -- --type=hello-world

# Dev
npx wrangler dev

# Deploy
npx wrangler deploy

# Production
npx wrangler deploy --env production

# Logs
npx wrangler tail

# Secrets
npx wrangler secret put API_KEY

bash

WebSocket#

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const upgradeHeader = request.headers.get('Upgrade');
    if (upgradeHeader !== 'websocket') {
      return new Response('Expected websocket', { status: 426 });
    }

    const [client, server] = Object.values(new WebSocketPair());
    server.accept();

    server.addEventListener('message', (event) => {
      server.send(`Echo: ${event.data}`);
    });

    server.addEventListener('close', () => {
      console.log('WebSocket closed');
    });

    return new Response(null, { status: 101, webSocket: client });
  },
};

typescript

Deploy từ GitHub#

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

on:
  push:
    branches: [main]

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

yaml

Middleware Pattern#

// auth.ts
export async function withAuth(request: Request, env: Env) {
  const token = request.headers.get('Authorization')?.split('Bearer ')[1];
  if (!token) {
    return new Response('Unauthorized', { status: 401 });
  }
  // Verify token
  const user = await verifyToken(token, env.JWT_SECRET);
  if (!user) {
    return new Response('Invalid token', { status: 401 });
  }
  request.user = user;
}

// cors.ts
export function withCors(response: Response) {
  response.headers.set('Access-Control-Allow-Origin', '*');
  response.headers.set('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE');
  response.headers.set('Access-Control-Allow-Headers', 'Content-Type, Authorization');
  return response;
}

typescript

Best Practices#

// 1. Cache everything có thể
const cacheKey = `api:${request.url}`;
const cached = await env.CACHE.get(cacheKey);
if (cached) return new Response(cached);

// 2. Response early, process late (ctx.waitUntil)
ctx.waitUntil(logAnalytics(request));

// 3. Streaming response
const stream = new ReadableStream({
  async start(controller) {
    controller.enqueue(new TextEncoder().encode('Hello '));
    await delay(100);
    controller.enqueue(new TextEncoder().encode('World'));
    controller.close();
  },
});
return new Response(stream);

// 4. Error handling
try {
  return await handleRequest(request, env);
} catch (err) {
  console.error('Handler failed:', err);
  return new Response('Internal error', { status: 500 });
}

typescript

Kết Luận#

Cloudflare Workers là nền tảng serverless edge tốt nhất hiện tại: không cold start, 330+ locations, giá rẻ. Kết hợp KV (cache), R2 (file), D1 (SQLite), AI (inference) — bạn có thể xây dựng toàn bộ ứng dụng mà không cần server truyền thống.

Cloudflare Workers — Serverless Ở Biên Toàn Cầu

Workers vs Lambda#

Hello World#

Routing#

Storage — KV, R2, D1#

KV — Key-Value Store#

R2 — Object Storage (S3-compatible)#

D1 — SQLite Database#

Env — Environment Variables#

Cron Triggers#

Workers AI#

Wrangler — CLI#

WebSocket#

Deploy từ GitHub#

Middleware Pattern#

Best Practices#

Kết Luận#

Tài liệu tham khảo#