[G1-Sync] Manual knowledge update

2026-05-10 22:08:15 +09:00
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+---
+id: backend-cron-workflows-inngest
+title: Inngest / Trigger.dev — function-as-a-workflow
+category: Coding
+status: draft
+source_trust_level: B
+verification_status: conceptual
+created_at: 2026-05-09
+updated_at: 2026-05-09
+tags: [backend, workflow, vibe-coding]
+tech_stack: { language: "TS", applicable_to: ["Backend"] }
+applied_in: []
+aliases: [Inngest, Trigger.dev, function workflow, durable function, event-driven, cron, retry]
+---
+
+# Inngest / Trigger.dev
+
+> Modern async / cron / workflow. **Code 가 function, retry / step / wait 자동**. Temporal 의 simple version.
+
+## 📖 핵심 개념
+- Function = workflow.
+- Step = retry / dedup unit.
+- Event 가 trigger.
+- Cron / wait 가 native.
+
+## 💻 코드 패턴
+
+### Inngest function
+```ts
+import { Inngest } from 'inngest';
+const inngest = new Inngest({ id: 'my-app' });
+
+export const dailyReport = inngest.createFunction(
+  { id: 'daily-report' },
+  { cron: '0 9 * * *' },
+  async ({ event, step }) => {
+    const data = await step.run('fetch', async () => fetchData());
+    
+    await step.sleep('wait', '1m');
+    
+    await step.run('email', async () => sendEmail(data));
+    
+    return { ok: true };
+  }
+);
+```
+
+→ 매 step 가 retry / dedup 자동.
+
+### Event-triggered
+```ts
+export const onUserSignup = inngest.createFunction(
+  { id: 'welcome-email' },
+  { event: 'user/signup' },
+  async ({ event, step }) => {
+    await step.run('send', () => sendWelcome(event.data.email));
+    
+    await step.sleep('wait-3-days', '3d');
+    
+    await step.run('check-active', async () => {
+      const user = await getUser(event.data.userId);
+      if (!user.active) await sendReengagement(user);
+    });
+  }
+);
+
+// Trigger
+await inngest.send({ name: 'user/signup', data: { userId, email } });
+```
+
+### Step.sleep (durable wait)
+```ts
+await step.sleep('wait', '1d');
+// → Function 가 종료. 1 day 후 resume.
+// → Server restart 가 OK (state durable).
+```
+
+→ Long-running workflow.
+
+### Step.waitForEvent
+```ts
+const event = await step.waitForEvent('payment-confirmed', {
+  event: 'payment/confirmed',
+  match: 'data.userId',
+  timeout: '1h',
+});
+
+if (!event) {
+  // Timeout
+}
+```
+
+→ "다음 event 가 도착 까지 wait".
+
+### Trigger.dev
+```ts
+import { client } from './trigger';
+
+client.defineJob({
+  id: 'daily-report',
+  trigger: cronTrigger({ cron: '0 9 * * *' }),
+  run: async (payload, io) => {
+    const data = await io.runTask('fetch', async () => fetchData());
+    await io.sendEvent('email', { name: 'send', payload: { data } });
+  },
+});
+```
+
+→ Inngest 와 매우 비슷.
+
+### Concurrency limit
+```ts
+{ concurrency: { limit: 10 } }
+// → 10 instance max parallel.
+```
+
+### Throttle
+```ts
+{ throttle: { limit: 100, period: '1m' } }
+// → 1 min 안 100 max.
+```
+
+### Retry policy
+```ts
+inngest.createFunction(
+  { id: 'task', retries: 5 },
+  ...
+  async ({ step }) => {
+    await step.run('flaky', async () => {
+      // Auto retry 5 times.
+    });
+  }
+);
+```
+
+### Cancel running function
+```ts
+{
+  cancelOn: [{ event: 'user/deleted', if: 'event.data.userId == async.data.userId' }]
+}
+```
+
+→ 외부 event 가 cancel.
+
+### Local dev
+```bash
+npx inngest-cli dev
+# → Dashboard at localhost:8288.
+```
+
+→ Function trace + replay + UI.
+
+### Production deploy
+```ts
+// Vercel / Cloudflare / Lambda
+// Inngest 가 serverless 친화.
+
+// app/api/inngest/route.ts (Next.js)
+import { serve } from 'inngest/next';
+import { dailyReport, onUserSignup } from '../../inngest';
+
+export const { GET, POST, PUT } = serve({
+  client: inngest,
+  functions: [dailyReport, onUserSignup],
+});
+```
+
+### vs Temporal
+```
+Temporal:
+- 강력 (workflow language).
+- Self-host 가 가능.
+- 큰 enterprise.
+- Steeper.
+
+Inngest:
+- TS-friendly.
+- Managed 친화.
+- Simple.
+- 작은 / 중간.
+
+→ Modern serverless = Inngest.
+큰 / on-prem = Temporal.
+```
+
+### vs BullMQ
+```
+BullMQ:
+- Redis-backed.
+- Self-host.
+- 더 raw.
+
+Inngest:
+- Managed.
+- Workflow primitive.
+- Step / sleep native.
+
+→ Inngest 가 더 production friendly.
+```
+
+### vs AWS Step Functions
+```
+Step Functions:
+- AWS native.
+- ASL (state machine).
+- Managed scaling.
+
+Inngest:
+- TS code (no DSL).
+- Multi-cloud.
+
+→ AWS-only = Step Functions.
+Multi-cloud / TS = Inngest.
+```
+
+### Use case
+```
+- Email sequence (welcome → 3 day → 7 day).
+- LLM agent workflow.
+- Image processing pipeline.
+- Daily report.
+- Subscription billing.
+- Scheduled cleanup.
+- Data sync (매 hour).
+```
+
+### LLM agent (Inngest)
+```ts
+export const agent = inngest.createFunction(
+  { id: 'agent' },
+  { event: 'agent/start' },
+  async ({ event, step }) => {
+    let context = event.data.task;
+    
+    for (let i = 0; i < 5; i++) {
+      const action = await step.run(`think-${i}`, async () => llm.complete(...));
+      
+      if (action.type === 'done') return action.result;
+      
+      const result = await step.run(`act-${i}`, async () => execute(action));
+      context += result;
+    }
+  }
+);
+```
+
+→ Multi-step agent + retry / pause / resume.
+
+### Idempotency
+```ts
+{
+  idempotency: 'event.data.orderId',
+}
+// → 같은 orderId 의 event 가 1번만.
+```
+
+### Batching
+```ts
+{
+  batchEvents: { maxSize: 100, timeout: '5s' }
+}
+// → 5 sec 또는 100 event 마다 batch.
+```
+
+### Cost
+```
+Inngest free: 1k step / month.
+Pro: $20-200 / month.
+
+Trigger.dev: 비슷.
+
+→ Self-host alternative 가 BullMQ + cron.
+```
+
+### Anti-pattern
+```
+- Step 안에 step.run 가 안: nested 안 됨.
+- Side effect 가 step.run 외: retry 시 중복.
+- Long step (>30 sec): timeout (function level).
+- Throw vs return error: 매 다름.
+```
+
+### Best practice
+```
+1. 매 side effect 가 step.run.
+2. Idempotent step (key).
+3. Concurrency / throttle (외부 API rate limit).
+4. Timeout (긴 wait 도).
+5. Error monitoring.
+```
+
+## 🤔 의사결정 기준
+| 상황 | 추천 |
+|---|---|
+| Modern serverless | Inngest / Trigger.dev |
+| 큰 / on-prem | Temporal |
+| Self-host simple | BullMQ |
+| AWS-only | Step Functions |
+| LLM agent | Inngest (durable + retry) |
+| Email sequence | Inngest (sleep) |
+
+## ❌ 안티패턴
+- **Side effect 가 step 외**: retry 중복.
+- **Long sleep 가 step.sleep 안**: function timeout.
+- **No idempotency**: replay 시 중복.
+- **No concurrency limit**: external API 폭발.
+- **Step 가 nested**: 안 됨.
+
+## 🤖 LLM 활용 힌트
+- Inngest = durable function + step.
+- Cron / event / wait native.
+- LLM agent 에 강함.
+- Temporal 의 simple alternative.
+
+## 🔗 관련 문서
+- [[Backend_Cron_Scheduler_Patterns]]
+- [[Backend_Job_Scheduling_Temporal]]
+- [[Backend_Saga_Choreography_vs_Orchestration]]