GitHub Actions로 Docker 이미지 빌드 및 레지스트리 배포 자동화

git push → GitHub Actions 트리거
→ 코드 체크아웃
→ Docker 이미지 빌드
→ 레지스트리 푸시 (GHCR / Docker Hub)
→ 서버에서 docker pull + 재시작

# .github/workflows/docker-build.yml

name: Docker Build & Push

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build-and-push:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Log in to GHCR
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch
            type=sha,prefix=sha-
            type=semver,pattern={{version}}

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build and push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Deploy to server
        if: github.ref == 'refs/heads/main'
        uses: appleboy/ssh-action@v1
        with:
          host: ${{ secrets.SERVER_HOST }}
          username: ${{ secrets.SERVER_USER }}
          key: ${{ secrets.SSH_PRIVATE_KEY }}
          script: |
            docker pull ghcr.io/${{ github.repository }}:main
            docker compose -f /opt/app/docker-compose.yml up -d app
            docker image prune -f

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Build and push (multi-arch)
        uses: docker/build-push-action@v5
        with:
          platforms: linux/amd64,linux/arm64
          push: true
          tags: ${{ steps.meta.outputs.tags }}