docker-build.sh

#!/usr/bin/env bash

readonly COMMIT=$(git rev-parse --short HEAD)
declare -l BRANCH # Make contents of the variable lowercase
readonly BRANCH=$(git rev-parse --abbrev-ref HEAD)
readonly TAG="whisker:${BRANCH}-${COMMIT}"

# Try to detect available docker commands.
function set_docker_cmd() {
    if [[ -z "${DOCKER_CMD}" ]]; then
        if command -v dockerd-rootless-infosun &>/dev/null; then
            DOCKER_CMD="dockerd-rootless-infosun --data-root /local/hdd/${USER}/docker -- docker"
        else
            DOCKER_CMD="docker"
        fi
        readonly DOCKER_CMD
    fi
}

# Helper function to run docker.
function my_docker() {
    set_docker_cmd
    eval "${DOCKER_CMD}" "$@"
}

function main() {
    echo "Building docker image of Whisker with tag ${TAG}"
    my_docker image build . -t "${TAG}" -f Dockerfile

    readonly tar_file="${TAG}.tar"
    echo "Saving image to ${tar_file}.gz"
    # Note: according to the docker documentation this command should be used:
    #   docker save tag | gzip > tarfile.tar.gz
    # But this leads to invalid TAR header errors when attempting to load the
    # tar file with docker again. In contrast, this command does work:
    my_docker save "${TAG}" -o "${tar_file}" && gzip -f "${tar_file}"
}

main