build and push backend image from backend

Author: iTrooz

.github/workflows/ci.yml

@@ -35,7 +35,40 @@ jobs:
         uses: actions/upload-pages-artifact@v3
         with:
           path: 'web/build/'
-  
+
+  build-backend-image:
+    name: Build
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+    steps:
+    - uses: actions/checkout@v4
+    - name: Log in to the Container registry
+      uses: docker/login-action@v3.3.0
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    # Needed to use gha caching
+    - name: Docker Setup Buildx
+      uses: docker/setup-buildx-action@v3.10.0
+      with: 
+        driver: docker-container
+        driver-opts: image=moby/buildkit:master,network=host
+
+    - name: Build and push Docker image
+      uses: docker/build-push-action@v4
+      if: github.event.repository.fork == false && github.ref_name == 'main'
+      with:
+        context: .
+        file: backend.Containerfile
+        push: true
+        cache-from: type=gha
+        cache-to: type=gha,mode=max
+        tags: |
+          ghcr.io/itrooz/modpackcreator/backend:latest
+
   upload_pages:
     name: Deploy to GitHub Pages
     runs-on: ubuntu-latest