try publishing to github packages

.github/workflows/publish.yml

@@ -0,0 +1,41 @@
+name: Publish Docker image
+on:
+  release:
+    types: [published]
+jobs:
+  github-cache:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      -
+        name: Cache Docker layers
+        uses: actions/cache@v2
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+      - name: Login to Github Packages registry
+        uses: docker/login-action@v1
+        with:
+          registry: docker.pkg.github.com
+          username: ${{ github.actor }}
+          password: ${{ github.token }}
+      -
+        name: Docker meta
+        id: docker_meta
+        uses: crazy-max/ghaction-docker-meta@v1
+        with:
+          images: fly-examples/nats-cluster # list of Docker images to use as base name for tags
+          tag-sha: true # add git short SHA as Docker tag
+      -
+        name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.docker_meta.outputs.tags }}
+          labels: ${{ steps.docker_meta.outputs.labels }}
+          cache-from: type=local,src=/tmp/.buildx-cache
+          cache-to: type=local,dest=/tmp/.buildx-cache