[actions] add `Docker publish` workflows #6

	name: Docker publish

	on:
	# schedule:
	# - cron: '18 5 * * *'
	push:
	branches: ["main"]

	env:
	REGISTRY: ghcr.io
	IMAGE_NAME: ${{ github.repository_owner }}/ubuntu

	jobs:
	publish:
	runs-on: ubuntu-latest
	permissions:
	contents: read
	packages: write
	id-token: write
	strategy:
	matrix:
	distro: [ubuntu]
	defaults:
	run:
	working-directory: ./${{ matrix.distro }}

	steps:
	- name: Checkout repository
	uses: actions/checkout@v4

	# Add support for more platforms with QEMU (optional)
	- name: Set up QEMU
	uses: docker/setup-qemu-action@v3

	# By default, builder driver is `docker`, which currently not supported
	# building multi-platform images or exporting cache.
	- name: Set up Docker Buildx
	uses: docker/setup-buildx-action@v3

	- name: Log into ${{ env.REGISTRY }}
	uses: docker/login-action@v3
	with:
	registry: ${{ env.REGISTRY }}
	username: ${{ github.actor }}
	password: ${{ secrets.GITHUB_TOKEN }}

	- name: Extract Docker metadata
	id: meta
	uses: docker/metadata-action@v5
	with:
	images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

	- name: Docker builder info
	run: \|
	set -x
	docker buildx version
	docker buildx ls
	docker buildx inspect

	pwd
	ls -ahl

	- name: Build and push Docker image
	id: publish
	uses: docker/build-push-action@v5
	with:
	context: ./${{ matrix.distro }}
	push: true
	tags: ${{ steps.meta.outputs.tags }}
	labels: ${{ steps.meta.outputs.labels }}
	cache-from: type=gha
	cache-to: type=gha,mode=max

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