diff --git a/.github/workflows/cd.yml b/.github/workflows/cd.yml
index 8213c97..8509f60 100644
--- a/.github/workflows/cd.yml
+++ b/.github/workflows/cd.yml
@@ -17,6 +17,7 @@ jobs:
         uses: actions/checkout@v4
 
       # https://github.com/superfly/flyctl-actions
+      # https://github.com/marketplace/actions/github-action-for-flyctl
       - name: Setup flyctl
         uses: superfly/flyctl-actions/setup-flyctl@master
 
@@ -30,6 +31,50 @@ jobs:
           # https://github.com/cao7113/hello-api-elixir/settings/secrets/actions
           FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}
 
+  push-to-registry:
+    name: Push Docker image to Docker Hub
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+      # attestations: write
+      id-token: write
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v4
+
+      # https://github.com/docker/login-action
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      # https://github.com/docker/metadata-action
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: cao7113/hello-api-elixir
+
+      # https://github.com/docker/build-push-action
+      - name: Build and push Docker image
+        id: push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+
+      # - 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
+
   release-tar:
     # strategy:
     #   matrix:
@@ -69,6 +114,7 @@ jobs:
       - name: Make Github release
         uses: softprops/action-gh-release@v2
         if: startsWith(github.ref, 'refs/tags/')
+        # todo: add runner.os & runner.arch info
         with:
           files: _build/prod/*.tar.gz