2nd/10_Wiki/Topic_Programming/DevOps_and_Security/Incremental_Build.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-incremental-build	Incremental Build	10_Wiki/Topics	verified	self	Incremental Compilation Cached Build Build Cache	none	A	0.9	applied	build ci performance monorepo caching		2026-05-10	pending	language framework typescript turborepo

Incremental Build

매 한 줄

"매 변경된 파일 + downstream 의존성만 rebuild — 매 hash-based caching 의 핵심". 매 1979 Make 의 mtime-based 시작, 매 2026 Turborepo/Nx/Bazel 의 content-addressed cache 가 default — 매 monorepo 에서 100x speedup 흔함.

매 핵심

매 작동 원리

• Input hash: 매 source files + deps + env → SHA256.
• Cache key: hash → output artifacts (dist/, .d.ts).
• Hit: cache 존재 → restore, skip work.
• Miss: rebuild, store.

매 granularity

• File-level: tsc --incremental (.tsbuildinfo).
• Task-level: Turborepo (per-package).
• Action-level: Bazel (per-rule, hermetic).

매 응용

1. Monorepo CI: 매 affected package 만 test.
2. Local dev: watch mode, 매 sub-second rebuild.
3. Docker: layer caching = path 별 invalidation.

💻 패턴

Turborepo pipeline

// turbo.json
{
  "$schema": "https://turbo.build/schema.json",
  "globalDependencies": ["tsconfig.base.json"],
  "tasks": {
    "build": {
      "dependsOn": ["^build"],
      "inputs": ["src/**", "package.json", "tsconfig.json"],
      "outputs": ["dist/**", ".next/**"],
      "cache": true
    },
    "test": {
      "dependsOn": ["build"],
      "inputs": ["src/**", "test/**"],
      "outputs": ["coverage/**"]
    },
    "lint": { "cache": true, "outputs": [] }
  },
  "remoteCache": { "signature": true }
}

TypeScript incremental

// tsconfig.json
{
  "compilerOptions": {
    "incremental": true,
    "tsBuildInfoFile": ".cache/tsbuild.json",
    "composite": true,
    "declaration": true,
    "declarationMap": true
  },
  "references": [
    { "path": "../core" },
    { "path": "../utils" }
  ]
}

Nx affected

# Only test packages affected by changes since main
nx affected --target=test --base=origin/main --head=HEAD --parallel=4

# Print affected graph
nx graph --affected --base=origin/main

Vite HMR (sub-second)

// vite.config.ts
import { defineConfig } from 'vite';
export default defineConfig({
  server: {
    hmr: { overlay: true },
    watch: { usePolling: false, ignored: ['**/node_modules/**', '**/dist/**'] }
  },
  build: {
    rollupOptions: { cache: true }
  },
  cacheDir: '.cache/vite'
});

GitHub Actions remote cache

- uses: actions/cache@v4
  with:
    path: |
      .turbo
      node_modules/.cache
    key: turbo-${{ runner.os }}-${{ hashFiles('**/pnpm-lock.yaml') }}-${{ github.sha }}
    restore-keys: turbo-${{ runner.os }}-${{ hashFiles('**/pnpm-lock.yaml') }}-

- run: pnpm turbo run build test --cache-dir=.turbo

Bazel hermetic action

# BUILD.bazel
load("@npm//@bazel/typescript:index.bzl", "ts_project")
ts_project(
    name = "core",
    srcs = glob(["src/**/*.ts"]),
    declaration = True,
    incremental = True,
    deps = ["//packages/utils"],
)

Cache hit ratio metric

// scripts/cache-stats.ts
import { execSync } from 'node:child_process';
const out = execSync('turbo run build --dry=json').toString();
const tasks = JSON.parse(out).tasks;
const hits = tasks.filter((t: any) => t.cache.status === 'HIT').length;
console.log(`cache hit: ${hits}/${tasks.length} = ${(hits/tasks.length*100).toFixed(1)}%`);

매 결정 기준

상황	Approach
Monorepo 10+ packages	Turborepo or Nx
Strict reproducibility	Bazel (hermetic)
Single TS app	tsc --incremental + Vite
Docker images	BuildKit + multi-stage layer cache

기본값: 매 Turborepo + remote cache (Vercel or self-hosted).

🔗 Graph

• 부모: Continuous Integration
• 응용: CI_CD_Pipeline
• Adjacent: Dependency Graph

🤖 LLM 활용

언제: 매 turbo.json/nx.json 의 generation, cache key tuning 추천. 언제 X: 매 Bazel hermetic rule — 매 strict, LLM hallucination 위험.

❌ 안티패턴

• Time-based keys: date +%s cache key — 매 hit 0%.
• Untracked inputs: env var, system clock 의존 → false hit.
• Cache everything: lint output 까지 cache → debugging 의 hell.
• No remote cache: CI 매 fresh 시작 → local-only 의 무의미.

🧪 검증 / 중복

• Verified (Turborepo 2.x, Nx 20+, Bazel 7+ 공식 docs).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — incremental build 의 hash caching 정리