Calculate a docker image's total size.

docker_image_size.sh

function docker_image_size() {
    local image=$1
    local sum=0
    local value
    for line in $(docker history $image | tail -n +2 | awk '{print $(NF-1) "-" $NF}'); do
        if [[ "$(echo $line | awk -F'-' '{print $2}')" == "B" ]]; then
            value=$(echo $line | awk -F'-' '{print $1}')
        elif [[ "$(echo $line | awk -F'-' '{print $2}')" == "kB" ]]; then
            kb=$(echo $line | awk -F'-' '{print $1}')
            value=$(echo "$kb * 1024" | bc -l)
        elif [[ "$(echo $line | awk -F'-' '{print $2}')" == "MB" ]]; then
            mb=$(echo $line | awk -F'-' '{print $1}')
            value=$(echo "$mb * 1024 * 1024" | bc -l)
        elif [[ "$(echo $line | awk -F'-' '{print $2}')" == "GB" ]]; then
            gc=$(echo $line | awk -F'-' '{print $1}')
            value=$(echo "$gb * 1024 * 1024 * 1024" | bc -l)
        fi
        sum=$(echo "$sum + $value" | bc -l)
    done

    echo "Total bytes: $sum"
    echo "Total kilobytes: $(echo $sum / 1024 | bc -l)"
    echo "Total megabytes: $(echo $sum / 1024 / 1024 | bc -l)"
    echo "Total gigabytes: $(echo $sum / 1024 / 1024 / 1024 | bc -l)"
}