cloudflare

Cloudflare

Cloudflare provides global edge networking, DDoS protection, edge serverless compute (Workers), and S3-compatible zero-egress object storage (R2).

When to Use

• Global Edge Compute with Cloudflare Workers: Executing serverless TypeScript/Rust code across 300+ global data centers with 0ms cold starts.
• Edge Storage (KV, R2, D1, Vectorize): Distributed key-value, S3-compatible object storage, serverless SQL, and vector indexing.
• DDoS Mitigation & Web Application Firewall (WAF): Protecting origins against layer 3/4/7 DDoS attacks and bots.
• Zero Trust Network Access (ZTNA) & Tunnels: Securely routing traffic to private services without opening public ports via cloudflared.

Quick Start

# Initialize and deploy a Cloudflare Worker using Wrangler
npm create cloudflare@latest my-edge-app -- --type hello-world
cd my-edge-app
npx wrangler dev    # Run locally with edge simulation
npx wrangler deploy # Deploy globally to 300+ edge locations

Core Concepts

Modern Cloudflare Worker with Fetch Handler

Sub-millisecond edge API handling requests:

// src/index.ts
export interface Env {
  CACHE_KV: KVNamespace;
  API_SECRET: string;
}

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

    if (url.pathname === "/api/geoip") {
      const country = request.cf?.country || "Unknown";
      const city = request.cf?.city || "Unknown";

      return Response.json({
        ip: request.headers.get("cf-connecting-ip"),
        country,
        city,
        colo: request.cf?.colo, // Cloudflare data center airport code
      });
    }

    // Check edge KV cache
    const cacheKey = `content:${url.pathname}`;
    const cached = await env.CACHE_KV.get(cacheKey);
    if (cached) {
      return new Response(cached, {
        headers: { "X-Cache": "HIT", "Content-Type": "application/json" },
      });
    }

    const payload = JSON.stringify({
      message: "Generated at edge",
      timestamp: Date.now(),
    });
    ctx.waitUntil(env.CACHE_KV.put(cacheKey, payload, { expirationTtl: 300 }));

    return new Response(payload, {
      headers: { "X-Cache": "MISS", "Content-Type": "application/json" },
    });
  },
};