Merge pull request cloudfoundry#19 from cloudfoundry/skipping-steps-f…

…or-forks

Skipping steps for forks

.github/workflows/image.yml

@@ -24,7 +24,23 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Prepare
+        id: prep
+        run: |
+          EVENT_NAME=${{ github.event_name }}
+          IS_FORK=${{ github.event.pull_request.head.repo.fork }}
+          if [ "$EVENT_NAME"=="push" ]; then
+            echo "::set-output name=should_push::true"
+          elif [ "$EVENT_NAME"=="pull_request" ]; then
+            if [ "$IS_FORK"=="true" ]; then
+              echo "::set-output name=should_push::false"
+            else
+              echo "::set-output name=should_push::true"
+            fi
+          fi
+
       - name: Log in to the Container registry
+        if: ${{ steps.prep.outputs.should_push == 'true' }}
         uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
         with:
           registry: ${{ env.REGISTRY }}
@@ -41,6 +57,6 @@ jobs:
         uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
         with:
           context: dockerfiles/autoscaler-${{ matrix.image_suffix }} 
-          push: true
+          push: ${{ steps.prep.outputs.should_push == 'true' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}