깃허브 액션 재사용 워크플로우, 컴포지트 액션, 매트릭스 | CI 중복을 어떻게 없애나?

.github/workflows/deploy-node.yml (재사용 워크플로우 — 정의)
# org/shared-workflows 저장소에 두는 예시
on:
  workflow_call:
    inputs:
      node-version:
        required: false
        type: string
        default: '20'
      environment:
        required: true
        type: string
    secrets:
      DEPLOY_TOKEN:
        required: true

jobs:
  deploy:
    runs-on: ubuntu-latest
    environment: ${{ inputs.environment }}
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: ${{ inputs.node-version }}
          cache: 'npm'

      - run: npm ci

      - run: npm run build

      - name: Deploy
        env:
          DEPLOY_TOKEN: ${{ secrets.DEPLOY_TOKEN }}
        run: bash scripts/deploy.sh

.github/workflows/ci.yml (호출자 저장소)
on:
  push:
    branches: [main]

jobs:
  deploy-prod:
    uses: org/shared-workflows/.github/workflows/deploy-node.yml@v1.2.0
    with:
      node-version: '20'
      environment: production
    secrets:
      DEPLOY_TOKEN: ${{ secrets.DEPLOY_TOKEN }}

.github/actions/setup-env/action.yml (로컬 컴포지트 예시)
name: 'Setup Environment'
description: 'Node.js 설치, npm ci, .env 복원'

inputs:
  node-version:
    description: 'Node.js 버전'
    required: false
    default: '20'
  env-content:
    description: '.env 파일 내용 (시크릿에서 전달)'
    required: false

outputs:
  cache-hit:
    description: 'npm 캐시 히트 여부'
    value: ${{ steps.cache.outputs.cache-hit }}

runs:
  using: 'composite'
  steps:
    - uses: actions/setup-node@v4
      with:
        node-version: ${{ inputs.node-version }}
        cache: 'npm'
      id: cache

    - run: npm ci
      shell: bash

    - name: Restore .env
      if: inputs.env-content != ''
      run: echo "${{ inputs.env-content }}" > .env
      shell: bash

.github/workflows/test.yml (매트릭스 + 재사용 워크플로우 조합)
on:
  pull_request:
    branches: [main, develop]

jobs:
  # 매트릭스는 호출자에서 선언
  test:
    strategy:
      fail-fast: false
      matrix:
        node: ['18', '20', '22']
        os: [ubuntu-latest, macos-latest]
    uses: org/shared-workflows/.github/workflows/test-node.yml@v2.0.0
    with:
      node-version: ${{ matrix.node }}
      os: ${{ matrix.os }}
    secrets: inherit

  # 매트릭스 결과를 한 곳에서 확인하는 체크
  test-result:
    needs: test
    runs-on: ubuntu-latest
    if: always()
    steps:
      - name: Check test results
        run: |
          if [[ "${{ needs.test.result }}" != "success" ]]; then
            echo "테스트 실패"
            exit 1
          fi

outputs로 잡 간 값 전달하기
# 재사용 워크플로우 출력 선언
on:
  workflow_call:
    outputs:
      image-tag:
        description: '빌드된 도커 이미지 태그'
        value: ${{ jobs.build.outputs.image-tag }}

jobs:
  build:
    runs-on: ubuntu-latest
    outputs:
      image-tag: ${{ steps.build-image.outputs.image-tag }}
    steps:
      - id: build-image
        run: |
          TAG="sha-${GITHUB_SHA::7}"
          echo "image-tag=$TAG" >> "$GITHUB_OUTPUT"

# 호출자에서 받기
jobs:
  build:
    uses: org/shared/.github/workflows/build.yml@v1
    secrets: inherit

  deploy:
    needs: build
    runs-on: ubuntu-latest
    steps:
      - run: echo "이미지 태그: ${{ needs.build.outputs.image-tag }}"