publish container to ghcr

.github/workflows/build-site-container.yml

@@ -1,8 +1,10 @@
-name: Build site container
+name: Build and publish site container
 
 on:
   push:
     branches: [main]
+    tags:
+      - "v*"
     paths:
       - "site/**"
       - ".github/workflows/build-container.yml"
@@ -14,6 +16,11 @@ on:
 
 permissions:
   contents: read
+  packages: write
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
 
 jobs:
   build:
@@ -23,8 +30,38 @@ jobs:
       - name: Check out repository
         uses: actions/checkout@v4
 
-      - name: Build container
-        run: docker build --tag kr0sh512-site:ci ./site
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
 
-      - name: Validate nginx configuration
-        run: docker run --rm kr0sh512-site:ci nginx -t
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Generate image metadata
+        id: metadata
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=raw,value=latest,enable={{is_default_branch}}
+            type=ref,event=branch
+            type=ref,event=tag
+            type=sha
+
+      - name: Build and publish container
+        uses: docker/build-push-action@v6
+        with:
+          context: ./site
+          platforms: linux/amd64
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.metadata.outputs.tags }}
+          labels: ${{ steps.metadata.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max