Lists dangling docker volumes and their sizes

dckr-volumes

#!/usr/bin/env bash
# Usage: dckr-volumes [OPTIONS]
# Lists dangling Docker volumes and their sizes.
# Options:
#     -h, --help    Shows this help message and exit
#     -a, --all     Lists all Docker volumes and their sizes, not only dangling ones
#     --no-header   Hides the header
#

set -euo pipefail

# loop through each volume and calculate its size
function list_vols_and_sizes() {

    # params
    no_header=false
    for arg in "$@"; do
        case $arg in
        --no-header)
            no_header=true
            ;;
        esac
    done

    # variables
    header_l1="VOLUME NAME,SIZE,CREATION DATE"
    header_l2="-----------,----,-------------"
    VOLUMES=${1}
    declare -a lines

    # gather info
    sudo -v -p "[sudo] I need root access to list volume sizes: "
    for volume_name in $VOLUMES; do
        SIZE=$(sudo du -sh "${DOCKER_VOLUME_DIR}/${volume_name}/_data" 2>/dev/null | awk '{print $1}')
        CREATION_DATE=$(docker volume inspect "${volume_name}" --format '{{.CreatedAt}}' | cut -d'T' -f1)
        LINE="${volume_name},${SIZE},${CREATION_DATE}"
        lines+=("${LINE}")
    done
    # sudo -k # commented out to avoid asking for password again on subsequent runs

    # sorting and formatting
    mapfile -t lines_sorted < <(printf "%s\n" "${lines[@]}" | sort -t, -k2 -h)
    if [[ "$no_header" == false ]]; then
        lines_sorted=("${header_l1}" "${header_l2}" "${lines_sorted[@]}")
    fi
    mapfile -t lines_fmt < <(printf "%s\n" "${lines_sorted[@]}" | column -t -s, -o " | ")

    # print formatted output
    for line in "${lines_fmt[@]}"; do
        echo "${line}"
    done
}

function show_help_and_exit() {
    echo -e "\n\tUsage: \033[34m$(basename "$0") [OPTIONS]\033[0m\n"
    echo -e "Lists dangling Docker volumes and their sizes."
    echo -e "\n\tOptions:"
    echo -e "\t    -h, --help    Shows this help message and exit"
    echo -e "\t    -a, --all     Lists all Docker volumes and their sizes, not only dangling ones"
    echo -e "\t    --no-header   Hides the header"
    echo -e "\n"
    exit 0
}

# List dangling Docker volumes and their sizes.
function main() {

    # directory where Docker volumes are stored.
    DOCKER_VOLUME_DIR="$(docker info --format '{{.DockerRootDir}}')/volumes"

    list_mode="dangling"
    no_header=false
    while getopts "ah-:" opt; do
        case $opt in
        a)
            list_mode="all"
            ;;
        h)
            show_help_and_exit
            ;;
        -)
            case "${OPTARG}" in
            all)
                list_mode="all"
                ;;
            no-header)
                no_header=true
                ;;
            help)
                show_help_and_exit
                ;;
            *)
                echo "Invalid long option: --${OPTARG}" >&2
                exit 1
                ;;
            esac
            ;;
        \?)
            echo "Invalid short option: -${OPTARG}" >&2
            exit 1
            ;;
        esac
    done
    shift $((OPTIND - 1))

    if [[ "$list_mode" == "dangling" ]]; then
        echo "Listing dangling volumes..." >&2
        VOLUMES=$(docker volume ls -qf dangling=true)
        echo "Found $(echo "${VOLUMES}" | wc -w) dangling volumes"
    else
        echo "Listing all volumes..." >&2
        VOLUMES=$(docker volume ls -q)
        echo "Found $(echo "${VOLUMES}" | wc -w) volumes (all volumes)" >&2
    fi

    if [[ "$no_header" == false ]]; then
        list_vols_and_sizes "${VOLUMES}"
    else
        list_vols_and_sizes "${VOLUMES}" --no-header
    fi

}

main "$@"