switch to live repo #4

	name: Build & push Docker image

	# Build the environment image whenever the environment changes (lockfile,
	# Dockerfile, or launcher) on ANY branch, plus a manual trigger.
	# - lock-<hash> and <sha> tags are pushed on every branch, so the smoke test
	# running on a feature branch can pull the freshly-built environment.
	# - :latest is pushed ONLY from main/develop, so feature branches never
	# overwrite the image end users pull.
	on:
	push:
	paths:
	- Dockerfile
	- start.sh
	- program/renv.lock
	workflow_dispatch:

	env:
	IMAGE: pauljonasjost/comicsart

	jobs:
	build:
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v4

	- name: Compute image tags
	id: meta
	run: \|
	HASH=$(sha256sum program/renv.lock \| cut -c1-8)
	{
	echo "tags<<EOF"
	echo "${IMAGE}:lock-${HASH}"
	echo "${IMAGE}:${{ github.sha }}"
	if [ "${{ github.ref }}" = "refs/heads/main" ] \|\| [ "${{ github.ref }}" = "refs/heads/develop" ]; then
	echo "${IMAGE}:latest"
	fi
	echo "EOF"
	} >> "$GITHUB_OUTPUT"

	- name: Log in to Docker Hub
	uses: docker/login-action@v3
	with:
	username: ${{ secrets.DOCKERHUB_USERNAME }}
	password: ${{ secrets.DOCKERHUB_TOKEN }}

	- name: Set up Buildx
	uses: docker/setup-buildx-action@v3

	- name: Build and push
	uses: docker/build-push-action@v6
	with:
	context: .
	file: Dockerfile
	platforms: linux/amd64
	push: true
	tags: ${{ steps.meta.outputs.tags }}
	cache-from: type=registry,ref=${{ env.IMAGE }}:buildcache
	cache-to: type=registry,ref=${{ env.IMAGE }}:buildcache,mode=max

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