docs(FAQ): add answer re: necessary specs, copy-edit existing answer … #6504

	name: Docker

	on:
	push:
	branches:
	- 'master'
	pull_request:
	types: [synchronize, opened, reopened, ready_for_review]

	jobs:
	config:
	runs-on: "ubuntu-latest"
	outputs:
	has-secrets: ${{ steps.check.outputs.has-secrets }}
	steps:
	- name: "Check for secrets"
	id: check
	shell: bash
	run: \|
	if [ -n "${{ (secrets.DOCKERHUB_USER != '' && secrets.DOCKERHUB_TOKEN != '') \|\| '' }}" ]; then
	echo "has-secrets=1" >> "$GITHUB_OUTPUT"
	echo "has secrets!"
	else
	echo "has-secrets=0" >> "$GITHUB_OUTPUT"
	echo "no secrets!"
	fi

	docker-build:
	needs: config
	if: needs.config.outputs.has-secrets
	name: docker-build
	runs-on: ubuntu-latest
	steps:
	- name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
	uses: actions/checkout@v3
	with:
	persist-credentials: false

	- shell: bash
	env:
	DOCKERHUB_USER: ${{ secrets.DOCKERHUB_USER }}
	DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
	run: \|
	.github/workflows/docker_build_push.sh

	- name: Build ephemeral env image
	if: github.event_name == 'pull_request'
	run: \|
	mkdir -p ./build
	echo ${{ github.sha }} > ./build/SHA
	echo ${{ github.event.pull_request.number }} > ./build/PR-NUM
	DOCKER_BUILDKIT=1 docker build --target ci -t ${{ github.sha }} -t "pr-${{ github.event.pull_request.number }}" .
	docker save ${{ github.sha }} \| gzip > ./build/${{ github.sha }}.tar.gz

	- name: Upload build artifacts
	if: github.event_name == 'pull_request'
	uses: actions/upload-artifact@v3
	with:
	name: build
	path: build/

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