retry() {
    local t0 cur_date remaining
    local timeout="${1:?error: no timeout given}"
    local period="${2:?error: no period given}"
    declare -a cmd=("${@:3}")

    t0="$(date '+%s')"
    until "${cmd[@]}"
    do
        sleep "$period"
        cur_date="$(date '+%s')"
        remaining=$((t0 + timeout - cur_date))
        [ "$remaining" -gt 0 ] || return 1
        echo "$remaining seconds remain before teardown"
    done
}