build.sh

#!/bin/bash -e

echo 'This script is used to build and push multi-arch images to a container registry.'
echo ''
echo 'The script is intended to be used in a CI/CD pipeline.'
echo ''
echo 'The following variables can be set:'
echo ''
echo '| variable       | value                                             | default value                 | required                    |'
echo '|----------------|---------------------------------------------------|-------------------------------|-----------------------------|'
echo '| EXECUTOR       | podman or docker                                  | podman or docker if available | optional                    |'
echo '| REGISTRY       | docker.io, quay.io, ...                           | docker.io                     | optional                    |'
echo '| REPOSITORY     | e.g. example-project                              | not set                       | required                    |'
echo '| IMAGE_NAME     | e.g. example                                      | not set                       | required                    |'
echo '| IMAGE_TAG      | e.g. v1.0.0                                       | latest commit sha             | optional                    |'
echo '| GIT_SHA        | e.g. 1234567890abcdef                             | latest commit sha             | required, if git is missing |'
echo '| CONTEXT        | e.g. ./example                                    | .                             | optional                    |'
echo '| CONTAINERFILE  | e.g. ./example/Dockerfile                         | Dockerfile                    | optional                    |'
echo '| PUSH           | if set, the image will be pushed to the registry  | not set                       | optional                    |'
echo '| ROBOT_USERNAME | username for the registry                         | not set                       | required, if PUSH is set    |'
echo '| ROBOT_PASSWORD | password for the registry                         | not set                       | required, if PUSH is set    |'
echo '| DEBUG          | if set, the script will be executed in debug mode | not set                       | optional                    |'
echo ''
echo 'All arguments after the first one will be passed to the build command as build-args.'
echo 'They should be in the format: ARG=VALUE'
echo ''
echo 'example: ./build.sh ARG1=VALUE1 ARG2=VALUE2'
echo ''
echo "starting build"

# Validate if required variables are set
if [[ -z "${EXECUTOR}" ]]; then
	echo "EXECUTOR not set"
	if which podman ; then
		echo "using podman as EXECUTOR"
		EXECUTOR=$(which podman)
	elif which docker ; then
		echo "using docker as EXECUTOR"
		EXECUTOR=$(which docker)
	else
		echo "no executor found on the system"
		exit 1
	fi
fi

if [[ -n "${DEBUG}" ]]; then
	set -x
	if [[ "${EXECUTOR}" == "podman" ]]; then
		EXTRA_FLAGS=(--log-level=debug)
	fi
fi

if [[ -z "${GIT_SHA}" ]]; then
	GIT_SHA=$(git rev-parse HEAD)
fi

if [[ -z "${REGISTRY}" ]]; then
	echo "REGISTRY not set"
	echo "using docker.io"
	REGISTRY='docker.io'
fi
if [[ -z "${REPOSITORY}" ]]; then
	echo "REPOSITORY not set"
	exit 1
fi
if [[ -z "${IMAGE_NAME}" ]]; then
	echo "IMAGE_NAME not set"
	exit 1
fi
# combine variables to easier refer to the image
IMAGE="${REGISTRY}"/"${REPOSITORY}"/"${IMAGE_NAME}"

if [[ -z "${IMAGE_TAG}" ]]; then
	echo "IMAGE_TAG not set"
	echo "tagging '${GIT_SHA}'"
	IMAGE_TAG="${GIT_SHA}"
else
	# validate if the tag is correct SEMVER without additional info
	if [[ "${IMAGE_TAG}" =~ ^v(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)$ ]]; then
		LATEST=1
	fi
fi

if [[ -z "${CONTEXT}" ]]; then
	echo "CONTEXT not set"
	echo "using '.'"
	CONTEXT='.'
fi

if [[ -z "${CONTAINERFILE}" ]]; then
	echo "CONTAINERFILE not set"
	echo "using 'Dockerfile'"
	CONTAINERFILE='Dockerfile'
fi

BUILD_ARGS=()
for ARG in "${@}"; do
	# add args to list
	BUILD_ARGS+=("--build-arg=${ARG}")
done

for ARCH in amd64 arm64; do
	"${EXECUTOR}" build \
		--tag="${IMAGE}":"${GIT_SHA}"-"${ARCH}" \
		--platform="linux/${ARCH}" \
		--file "${CONTAINERFILE}" \
		"${BUILD_ARGS[@]}" \
		--pull \
		--rm \
		"${EXTRA_FLAGS[@]}" \
		"${CONTEXT}"
done

if [[ -n "${PUSH}" ]]; then
	# Login into the container registry:
	"${EXECUTOR}" login \
		"${EXTRA_FLAGS[@]}" \
		--username "${ROBOT_USERNAME}" \
		--password "${ROBOT_PASSWORD}" \
		"${REGISTRY}"

	# Set manifest name
	export MANIFEST_NAME="${IMAGE}":"${IMAGE_TAG}"

	MANIFESTS=()
	for ARCH in amd64 arm64; do
		MANIFESTS+=("${IMAGE}":"${GIT_SHA}"-"${ARCH}")
	done

	# Create a multi-architecture manifest
	if ! "${EXECUTOR}" manifest create --amend "${MANIFEST_NAME}" "${MANIFESTS[@]}"; then
		echo "creation of manifest failed"
		exit 1
	fi

	for ARCH in amd64 arm64; do
		"${EXECUTOR}" manifest add \
			"${EXTRA_FLAGS[@]}" \
			"${MANIFEST_NAME}" \
			"${IMAGE}":"${GIT_SHA}"-"${ARCH}"
	done

	# Push the full manifest, with all CPU Architectures, with IMAGE_TAG tag
	"${EXECUTOR}" manifest push \
		--all \
		"${EXTRA_FLAGS[@]}" \
		"${MANIFEST_NAME}" \
		docker://"${IMAGE}":"${IMAGE_TAG}";

	if [[ -n "${LATEST}" ]]; then
		# Push the full manifest, with all CPU Architectures, with latest tag
		"${EXECUTOR}" manifest push \
			--all \
			"${EXTRA_FLAGS[@]}" \
			"${MANIFEST_NAME}" \
			docker://"${IMAGE}":latest;
	fi
fi