Add workflow to build a ctsm container for unit testing #3

	name: Build and Push CTSM Container

	on:
	# We could have ctsm send out a trigger for this workflow
	# repository_dispatch:
	# types: [new-tag]
	workflow_dispatch:
	pull_request:
	branches: [main]
	paths:
	- '.github/workflows/ctsm-build.yml'

	jobs:
	build-and-push:
	runs-on: ubuntu-latest

	permissions:
	contents: read
	packages: write

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

	- name: Log in to GitHub Container Registry
	uses: docker/login-action@v3
	with:
	registry: ghcr.io
	username: ${{ github.actor }}
	password: ${{ secrets.GITHUB_TOKEN }}

	- name: Set up Docker Buildx
	uses: docker/setup-buildx-action@v3
	with:
	buildkitd-flags: --debug

	- name: Lowercase the github.repository name
	# This step addresses https://github.com/orgs/community/discussions/25768
	run: \|
	echo "REPO_NAME=`echo ${{ github.repository }} \| tr '[:upper:]' '[:lower:]'`" >> $GITHUB_ENV

	- name: Build and push image
	uses: docker/build-push-action@v6
	with:
	context: ./unit-testing/
	push: true
	tags: ghcr.io/${{ env.REPO_NAME}}/unit-test-ctsm:latest
	cache-from: type=gha
	cache-to: type=gha,mode=max

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