Enhance Docker publish workflow with metadata and caching

Added environment variables for registry and image name. Updated Docker build and push steps to include metadata extraction and caching.

.github/workflows/docker-publish.yml

@@ -6,9 +6,17 @@ on:
   pull_request:
     branches: [ "main" ]
 
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
 jobs:
   build:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
     steps:
     - uses: actions/checkout@v3
     
@@ -18,9 +26,32 @@ jobs:
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3
       
+    - name: Log in to the Container registry
+      uses: docker/login-action@v3
+      with:
+        registry: ${{ env.REGISTRY }}
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+        
+    - name: Extract metadata (tags, labels) for Docker
+      id: meta
+      uses: docker/metadata-action@v5
+      with:
+        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+        tags: |
+          type=ref,event=branch
+          type=ref,event=pr
+          type=semver,pattern={{version}}
+          type=sha
+          latest
+      
     - name: Build and push
       uses: docker/build-push-action@v5
       with:
         context: ./backend
-        push: false
-        tags: user/app:latest
+        push: true
+        tags: ${{ steps.meta.outputs.tags }}
+        labels: ${{ steps.meta.outputs.labels }}
+        platforms: linux/amd64,linux/arm64
+        cache-from: type=gha
+        cache-to: type=gha,mode=max