Update README #355

	name: docker

	on:
	push:
	branches: main
	tags: ["*"]

	jobs:
	build:
	runs-on: ubuntu-22.04
	steps:
	- uses: actions/checkout@v3
	- name: Install packages
	run: \|
	sudo apt-get update
	sudo apt-get install -y autoconf automake build-essential cmake curl file libtool
	- name: Cross build multi-arch binary
	run: \|
	mkdir dist
	for arch in amd64 armv7 arm64 s390x; do
	env BUILD_TARGET=$arch ./scripts/cross-build.sh
	[ "$arch" = "armv7" ] && arch="arm"
	mkdir -p dist/$arch && cp build/ttyd dist/$arch/ttyd
	done
	- uses: docker/setup-qemu-action@v2
	- uses: docker/setup-buildx-action@v2
	- uses: docker/login-action@v2
	with:
	username: ${{ secrets.DOCKER_HUB_USER }}
	password: ${{ secrets.DOCKER_HUB_TOKEN }}
	- name: Determine docker tags
	id: docker_tag
	run: \|
	case $GITHUB_REF in
	refs/tags/*)
	TAG_NAME=${GITHUB_REF#refs/tags/}
	echo "DOCKER_TAG=tsl0922/ttyd:${TAG_NAME}" >> $GITHUB_ENV
	echo "ALPINE_TAG=tsl0922/ttyd:${TAG_NAME}-alpine" >> $GITHUB_ENV
	;;
	*)
	echo "DOCKER_TAG=tsl0922/ttyd:latest" >> $GITHUB_ENV
	echo "ALPINE_TAG=tsl0922/ttyd:alpine" >> $GITHUB_ENV
	esac
	- name: build/push docker image
	uses: docker/build-push-action@v3
	with:
	context: .
	file: ./Dockerfile
	platforms: linux/amd64,linux/arm/v7,linux/arm64,linux/s390x
	push: true
	tags: ${{ env.DOCKER_TAG }}
	- name: build/push docker image (alpine)
	uses: docker/build-push-action@v3
	with:
	context: .
	file: ./Dockerfile.alpine
	platforms: linux/amd64,linux/arm/v7,linux/arm64,linux/s390x
	push: true
	tags: ${{ env.ALPINE_TAG }}

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