💚 Save image to ghcr in ci

.github/workflows/container.yml

@@ -0,0 +1,33 @@
+name: 'build container'
+on: # rebuild any PRs and main branch changes
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout (GitHub)
+        uses: actions/checkout@v3
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Pre-build image and run make ci-build in dev container
+        uses: devcontainers/[email protected]
+        with:
+          imageName: ghcr.io/red-data-tools/red_amber
+          cacheFrom: ghcr.io/red-data-tools/red_amber
+          push: always
+          runCmd: bundle exec test