Merge pull request #210 from NotActuallyTerry/notactuallyterry/docker… #36

	name: Docker

	on:
	push:
	# Publish `main` as Docker `latest` image.
	branches:
	- main
	- docker-publish

	# Publish `v1.2.3` tags as releases.
	tags:
	- v*

	env:
	IMAGE_NAME: default

	jobs:
	push:

	runs-on: ubuntu-latest
	if: github.event_name == 'push'

	steps:
	- uses: actions/checkout@v2

	- name: Build image
	run: docker build . --file Dockerfile --tag $IMAGE_NAME --cache-from ghcr.io/${{ github.repository }}:latest

	- name: Login to GitHub Container Registry
	uses: docker/login-action@v1
	with:
	registry: ghcr.io
	username: ${{ github.actor }}
	password: ${{ secrets.GITHUB_TOKEN }}

	- name: Push image
	run: \|
	IMAGE_ID=ghcr.io/${{ github.repository }}
	# Change all uppercase to lowercase
	IMAGE_ID=$(echo $IMAGE_ID \| tr '[A-Z]' '[a-z]')
	# Strip git ref prefix from version
	VERSION=$(echo "${{ github.ref }}" \| sed -e 's,./$.$,\1,')
	# Strip "v" prefix from tag name
	[[ "${{ github.ref }}" == "refs/tags/"* ]] && VERSION=$(echo $VERSION \| sed -e 's/^v//')
	# Use Docker `latest` tag convention
	[ "$VERSION" == "main" ] && VERSION=latest
	echo IMAGE_ID=$IMAGE_ID
	echo VERSION=$VERSION
	docker tag $IMAGE_NAME $IMAGE_ID:$VERSION
	docker push $IMAGE_ID:$VERSION

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