[G1-Sync] Manual knowledge update
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Antigravity Agent
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---
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id: backend-edge-functions
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title: Edge Functions — Cloudflare / Vercel / Deno Deploy
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category: Coding
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status: draft
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source_trust_level: B
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verification_status: conceptual
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created_at: 2026-05-09
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updated_at: 2026-05-09
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tags: [backend, edge, serverless, vibe-coding]
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tech_stack: { language: "TS", applicable_to: ["Backend"] }
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applied_in: []
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aliases: [Cloudflare Workers, Vercel Edge, Deno Deploy, edge runtime, V8 isolate, Wasm edge]
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---
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# Edge Functions
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> 사용자 가까이 (300+ region) 실행. **Cloudflare Workers / Vercel Edge / Deno Deploy / Fastly Compute@Edge**. V8 isolate (cold start ms), 작은 limit.
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## 📖 핵심 개념
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- V8 Isolate: process 안 — 매 request fast.
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- Web Standard: Request / Response / fetch.
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- Limits: CPU / memory / time 작음.
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- Storage: KV / D1 / Durable Object / R2.
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## 💻 코드 패턴
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### Cloudflare Workers
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```ts
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// src/index.ts
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export interface Env {
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DB: D1Database;
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CACHE: KVNamespace;
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BUCKET: R2Bucket;
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}
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export default {
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async fetch(req: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
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const url = new URL(req.url);
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if (url.pathname === '/api/users/me') {
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const userId = await getUserId(req);
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const cached = await env.CACHE.get(`user:${userId}`, { type: 'json' });
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if (cached) return Response.json(cached);
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const user = await env.DB.prepare('SELECT * FROM users WHERE id = ?').bind(userId).first();
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ctx.waitUntil(env.CACHE.put(`user:${userId}`, JSON.stringify(user), { expirationTtl: 60 }));
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return Response.json(user);
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}
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return new Response('Not found', { status: 404 });
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},
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};
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```
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```toml
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# wrangler.toml
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name = "my-api"
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main = "src/index.ts"
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compatibility_date = "2024-12-01"
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[[d1_databases]]
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binding = "DB"
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database_name = "my-app"
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database_id = "..."
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[[kv_namespaces]]
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binding = "CACHE"
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id = "..."
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[[r2_buckets]]
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binding = "BUCKET"
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bucket_name = "uploads"
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[observability]
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enabled = true
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```
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```bash
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wrangler dev
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wrangler deploy
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```
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### Vercel Edge Function
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```ts
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// app/api/users/route.ts
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import { type NextRequest } from 'next/server';
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export const runtime = 'edge';
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export async function GET(req: NextRequest) {
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const id = req.nextUrl.searchParams.get('id');
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return Response.json({ id });
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}
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```
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```ts
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// 또는 standalone
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// pages/api/edge.ts
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export const config = { runtime: 'edge' };
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export default function handler(req: Request) {
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return new Response('Hello from edge');
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}
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```
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### Deno Deploy
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```ts
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import { Hono } from 'hono';
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const app = new Hono();
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app.get('/', (c) => c.text('Hello from Deno Deploy'));
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Deno.serve(app.fetch);
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```
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```bash
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deployctl deploy --project=my-app src/index.ts
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```
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### Bun on edge (Fly.io / Railway)
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```
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Bun = full Node API + Web Standard.
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Fly / Railway 가 Bun runtime 지원.
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Edge X but 가까운 region.
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```
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### KV (Cloudflare)
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```ts
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// 빠른 read (eventually consistent globally)
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await env.KV.put('key', 'value', { expirationTtl: 3600 });
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const v = await env.KV.get('key');
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const json = await env.KV.get('key', { type: 'json' });
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// List
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const list = await env.KV.list({ prefix: 'user:' });
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// Stream large
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const stream = await env.KV.get('large-file', { type: 'stream' });
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```
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→ Read 빠름 (각 region cache), write 글로벌 propagate (1-60s).
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### D1 (SQLite at edge)
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```ts
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const r = await env.DB.prepare('SELECT * FROM users WHERE email = ?')
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.bind('a@b.com')
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.first();
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// Multi
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const all = await env.DB.prepare('SELECT * FROM users WHERE status = ?')
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.bind('active')
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.all();
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// Batch (transaction)
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await env.DB.batch([
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env.DB.prepare('INSERT INTO users VALUES (?, ?)').bind(id1, email1),
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env.DB.prepare('INSERT INTO users VALUES (?, ?)').bind(id2, email2),
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]);
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```
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### Durable Objects (글로벌 state)
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```ts
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// Counter — 한 instance per name, 글로벌 단일
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export class Counter {
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state: DurableObjectState;
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constructor(state: DurableObjectState) {
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this.state = state;
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}
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async fetch(req: Request): Promise<Response> {
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let count = (await this.state.storage.get<number>('count')) ?? 0;
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count++;
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await this.state.storage.put('count', count);
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return Response.json({ count });
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}
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}
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// Worker
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export default {
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async fetch(req: Request, env: Env) {
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const url = new URL(req.url);
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const name = url.searchParams.get('room') ?? 'default';
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const id = env.COUNTER.idFromName(name);
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const stub = env.COUNTER.get(id);
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return stub.fetch(req);
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},
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};
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```
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→ Stateful — chat room, game session, rate limit.
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### R2 (S3-compatible storage)
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```ts
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const obj = await env.BUCKET.get('photo.jpg');
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if (obj) return new Response(obj.body, { headers: { 'Content-Type': obj.httpMetadata?.contentType ?? '' } });
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await env.BUCKET.put('upload.jpg', file, {
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httpMetadata: { contentType: 'image/jpeg' },
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});
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await env.BUCKET.delete('old.jpg');
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```
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→ S3-compat + free egress.
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### Cron triggers
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```toml
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# wrangler.toml
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[triggers]
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crons = ["0 9 * * *"] # 매일 9시
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```
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```ts
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export default {
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async scheduled(event: ScheduledEvent, env: Env, ctx: ExecutionContext) {
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await runDailyTask(env);
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},
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async fetch(req: Request, env: Env) { ... },
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};
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```
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### Queues (Cloudflare)
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```ts
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// Producer
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await env.QUEUE.send({ orderId: '...', userId: '...' });
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// Consumer
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export default {
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async queue(batch: MessageBatch, env: Env) {
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for (const msg of batch.messages) {
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await processOrder(msg.body);
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msg.ack();
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}
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},
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};
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```
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→ Decouple.
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### Limits (대략)
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```
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Cloudflare Workers:
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- CPU: 30s (paid) / 10ms (free) per request
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- Memory: 128 MB
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- Subrequests: 1000
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- Bundle: 10 MB
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- Compute units / month: $5 = 10M+
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Vercel Edge:
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- CPU: 30s
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- Memory: 128 MB
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- Bundle: 1 MB
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Deno Deploy:
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- CPU: 50ms (per request)
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- Memory: 512 MB
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```
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→ Long-running task = 다른 (Lambda / VM).
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### Edge 의 함정
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```
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1. CPU limit (10ms free) — 큰 work X.
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2. Bundle size — Node module 일부 X.
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3. Cold start — 거의 0 (V8 isolate).
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4. Connection pool 어려움 (no persistent state).
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5. 일부 Node API X (fs, child_process).
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```
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→ HTTP / KV / D1 만 사용.
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### Use cases (적합)
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```
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- API gateway (auth, rate limit, route)
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- A/B test, geo redirect
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- Image / response transformation
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- Analytics ingestion
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- Search index 호출
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- Cache layer
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- Webhook receiver
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- Static site SSR
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```
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### Use cases (안 적합)
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```
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- 큰 ML inference
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- Long task (1 min+)
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- Persistent connection (DB pool)
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- File system 의존
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- Large dependencies (Node-specific)
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```
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### Multi-region database
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```
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Edge function 가 사용자 가까이.
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DB 가 single region = 큰 latency.
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해결:
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- Read replica per region
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- Hyperdrive (CF cache)
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- Turso embedded replica
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- 분산 DB (Spanner, Yugabyte)
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```
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### Auth at edge
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```ts
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import { jwt } from 'hono/jwt';
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app.use('/api/*', jwt({ secret: env.JWT_SECRET }));
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// 또는 직접
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async function verifyJwt(token: string, secret: string) {
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const [header, payload, signature] = token.split('.');
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// JWT verify (jose 같은 lib)
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return JSON.parse(atob(payload));
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}
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```
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### Static + Edge function
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```
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Vercel / Cloudflare Pages:
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- Static assets — CDN
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- API routes — edge function
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→ Most modern stack.
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```
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### Streaming
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```ts
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export default {
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async fetch() {
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const { readable, writable } = new TransformStream();
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const writer = writable.getWriter();
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(async () => {
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for (let i = 0; i < 5; i++) {
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await writer.write(new TextEncoder().encode(`chunk ${i}\n`));
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await new Promise(r => setTimeout(r, 1000));
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}
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writer.close();
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})();
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return new Response(readable);
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},
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};
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```
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→ SSE / streaming response.
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### Test (local)
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```bash
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wrangler dev # local + miniflare (Cloudflare emulator)
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vercel dev
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deno run --watch src/index.ts
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```
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### Deploy
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```bash
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wrangler deploy --env production
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vercel --prod
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deployctl deploy --prod
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```
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### Cost
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```
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Cloudflare Workers:
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Free: 100K req/day
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Paid: $5/month + $0.50 per million
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Vercel:
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Hobby: free
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Pro: $20/month + execution time
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```
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→ 가장 cheap edge.
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### Comparison
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```
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Cloudflare:
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+ 가장 빠름 (V8 isolate)
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+ KV / D1 / R2 통합
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+ Free tier 강
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- Node API 제한
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Vercel:
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+ Next.js 통합 (best)
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+ Frontend / API 통합
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- 비싸 (큰 traffic)
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Deno Deploy:
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+ Deno native
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+ Web Standard
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- Smaller ecosystem
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Fastly Compute@Edge:
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+ Wasm 지원
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+ 큰 enterprise
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```
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## 🤔 의사결정 기준
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| 상황 | 추천 |
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|---|---|
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| 빠른 API + 글로벌 | Cloudflare Workers |
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| Next.js | Vercel Edge |
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| Deno project | Deno Deploy |
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| Wasm | Fastly / CF Workers |
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| Long task | Lambda / VM |
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| Big data | Container / VM |
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## ❌ 안티패턴
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- **Edge 안 long task**: timeout.
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- **Big bundle (큰 dep)**: limit.
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- **Node-specific (fs, net)**: 깨짐.
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- **DB persistent connection**: HTTP driver.
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- **Edge 가 모든 답**: 가까운 user 가 critical 시만.
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- **State in memory**: cold isolate 에 잃음. KV / DO.
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## 🤖 LLM 활용 힌트
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- Cloudflare Workers + D1 + KV = 가장 강.
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- Vercel Edge + Next.js = best DX.
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- Web Standard API only.
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- Cold start 거의 0.
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## 🔗 관련 문서
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- [[Backend_Hono_Modern]]
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- [[DB_Serverless_Edge]]
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- [[Backend_Geo_Replication]]
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