[workflows] Minimal workflow to create an AArch64 container #6

	name: Pre-compile llvm ARM64

	on:
	workflow_dispatch:
	inputs:
	initialBuild:
	description: "True if creating an initial Docker image for this branch"
	required: true
	type: boolean
	push:
	branches:
	- 'release_*x'
	paths-include:
	- '**/.github/workflows/build_push_docker_image_Ubuntu.yml'
	- '**/.github/workflows/UbuntuDockerfile.yml'

	jobs:
	docker:
	runs-on: self-hosted
	steps:
	- name: Extract branch name
	run: echo "::set-output name=branch::${GITHUB_REF#refs/heads/}"
	id: extract_branch

	- name: Checkout
	uses: actions/checkout@v2

	- name: Set up Docker Buildx
	uses: docker/setup-buildx-action@v1

	- name: Log in
	uses: docker/login-action@v1
	with:
	registry: ghcr.io
	username: ${{ github.repository_owner }}
	password: ${{ secrets.GITHUB_TOKEN }}

	- name: Build and push
	uses: docker/build-push-action@v2
	with:
	file: .github/workflows/UbuntuDockerfile
	push: true
	no-cache: true
	context: .github/workflows
	tags: ghcr.io/${{ github.repository_owner }}/ubuntu-flang-${{ steps.extract_branch.outputs.branch }}:latest
	platforms: linux/arm64
	build-args: \|
	BRANCH_NAME=${{ steps.extract_branch.outputs.branch }}
	INITIAL_BUILD=${{ inputs.initialBuild }}

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