ci(docker-build): add workflow for building ci images

.github/workflows/docker-build.yml

@@ -0,0 +1,41 @@
+---
+#
+# https://docs.docker.com/build/ci/github-actions/
+# https://github.com/docker/build-push-action
+# https://docs.github.com/en/actions/creating-actions/creating-a-docker-container-action
+#
+name: ci
+on:  # yamllint disable-line rule:truthy
+  schedule:
+    #         ┌───────────── minute (0 - 59)
+    #         │ ┌───────────── hour (0 - 23)
+    #         │ │ ┌───────────── day of the month (1 - 31)
+    #         │ │ │ ┌───────────── month (1 - 12 or JAN-DEC)
+    #         │ │ │ │ ┌───────────── day of the week (0 - 6 or SUN-SAT)
+    #         │ │ │ │ │
+    #         │ │ │ │ │
+    #         │ │ │ │ │
+    #         * * * * *
+    - cron: '15 8 1 * *'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: ${{ secrets.DOCKERHUB_USERNAME }}/ci-generic-alpine:latest

Dockerfile

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+#
+# Dockerfile: ci-generic-debian
+#
+
+From debian:bullseye-slim As ci-generic-base
+
+# Copies your code file from your action repository to the filesystem path `/` of the container
+COPY .github/docker/entrypoint.sh /entrypoint.sh
+
+# app + args
+# Executes `entrypoint.sh` when the Docker container starts up
+ENTRYPOINT ["/entrypoint.sh"]
+
+# extra args
+# CMD []