CI: publish docker image

.github/workflows/docker-build.yml

@@ -1,24 +1,41 @@
-name: Build Docker Image
+name: Build and Push Docker Image
 
 on:
   push:
     branches:
       - main
     tags:
-      - 'v*'
+      - '*'
 
 jobs:
-  build:
+  docker:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
     steps:
-    - uses: actions/checkout@v2
-    - name: Build Docker image
-      run: docker build . --file Dockerfile --tag my-image-name:$(git rev-parse --short HEAD)
-    # Publish to DockerHUB. Necessary?
-    # - name: Log in to DockerHub
-    #   uses: docker/login-action@v1
-    #   with:
-    #     username: ${{ secrets.DOCKER_USERNAME }}
-    #     password: ${{ secrets.DOCKER_PASSWORD }}
-    # - name: Push Docker image
-    #   run: docker push my-image-name:$(git rev-parse --short HEAD)
+      - name: Check out the repo
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.CR_PAT }}
+
+      - name: Extract tag name
+        id: tag_name
+        run: echo "TAG_NAME=${GITHUB_REF#refs/tags/}" >> $GITHUB_ENV
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: ghcr.io/${{ github.repository }}/kube-downscaler:${{ env.TAG_NAME }}