ci: add GitHub Actions workflow for Docker image builds

- Add GitHub Actions workflow for building and pushing Docker images
- Trigger workflow on push to `main` branch and tags matching `v*`
- Set up QEMU and Docker Buildx for multi-platform builds
- Log in to GitHub Container Registry using secrets
- Generate Docker metadata for image tagging
- Build and push Docker images to GitHub Container Registry with caching enabled

Signed-off-by: Bo-Yi Wu <[email protected]>

.github/workflows/docker.yaml

@@ -0,0 +1,58 @@
+name: Docker Image
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "v*"
+
+jobs:
+  build-docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Docker meta
+        id: docker-meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ghcr.io/${{ github.repository }}
+          tags: |
+            type=raw,value=latest,enable={{is_default_branch}}
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+
+      - name: downcase REPO
+        run: |
+          echo "REPO=${GITHUB_REPOSITORY,,}" >> ${GITHUB_ENV}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: homework03
+          platforms: linux/amd64,linux/arm,linux/arm64
+          file: Dockerfile
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.docker-meta.outputs.tags }}
+          labels: ${{ steps.docker-meta.outputs.labels }}
+          cache-from: type=registry,ref=ghcr.io/${{ env.REPO }}:buildcache
+          cache-to: type=registry,ref=ghcr.io/${{ env.REPO }}:buildcache,mode=max