change action to follow gh docs

.github/workflows/build-push.yaml

@@ -11,13 +11,17 @@ on:
       - contactform/**/*
       - .github/workflows/build-push.yaml
 
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
 jobs:
   build:
     runs-on: ubuntu-latest
     permissions:
       contents: read
       packages: write
-      id-token: write
+      attestations: write
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -28,10 +32,16 @@ jobs:
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with:
-          registry: ghcr.io
+          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 }}
+
       - name: Cache Docker layers
         uses: actions/cache@v4
         with:
@@ -40,12 +50,20 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-buildx-
 
-      - name: Build and Push Docker Image
-        uses: docker/build-push-action@v5
+      - name: Build and Push Docker image
+        id: push
+        uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
         with:
           context: .
-          file: ./Dockerfile
-          tags: ghcr.io/vshn/conferenceli:latest
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache
-          push: true
+
+      - name: Generate artifact attestation
+        uses: actions/attest-build-provenance@v1
+        with:
+          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}
+          subject-digest: ${{ steps.push.outputs.digest }}
+          push-to-registry: true