Upload Docker images to ghcr.io

Author: lucacome

.github/workflows/ci.yml

@@ -130,6 +130,13 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
         if: github.event_name != 'pull_request'
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+        if: github.event_name != 'pull_request'
       - name: Setup QEMU
         uses: docker/setup-qemu-action@v1
         with:
@@ -143,6 +150,7 @@ jobs:
         with:
           images: |
             nginx/nginx-ingress-operator
+            ghcr.io/nginxinc/nginx-ingress-operator
           tags: |
             type=edge
             type=ref,event=pr