Project Libre Cloud Poor Man Style

Disclaimer: The solution presented here is macOS only!

Some weeksago we encountered the need for some project management tool in my team at my employer. We’re a central security team providing services to our project teams and customers. The last months we saw more and more demand for our services and we’re faced a quite complex situation. We need to allocate the team members to some small projects (like threat modelings or a security training) or larger projects (like implementing secureCodeBox in a project or consulting a customer to build their own security community). Alsowe have to do internal security stuff.

First attempt was to do it with Excel, of course 😬 But Excel lacks one major feature: You can’t really model something in three dimensions. Of course, it’s made for tables which have two dimensions. But a typical project team allocation problem spans over three dimensions:

1. The projects to be done,
2. the team members,
3. and finally time.

Here typical project management tools (such as MS Project or Project Libre) come into play. They don’t really show you something in 3D, but they try more or less good to model these three dimensions. (There are resource plans, Gantt charts and cumulative resource diagrams and such.) You see, I’m not a project management geek 😉

We decided to give Project Libre a try and find out if it helps us with our problem. But there is one major use case Project Libre does not address: Concurrent modification of the data. Since we don’t have one single project manager, but a self-organized agile team instead, it is necessary that more than one person edits the file. We decided to give our business cloud storage a try. Problem: Project Libre does not create a lock on opening a file. So, it is possible to run into a lost update problem, if two or more persons edit the file concurrently.

Project Libre Enterprise for the rescue, I thought. But it is closed beta. Not much information and looking into the few screenshots, it seem to be a complete different UI.

My colleague came up with the idea of a wrapper script which checks and creates for a lock file. I say “hold my 🍺”:

#!/usr/bin/env bash

set -euo pipefail

#
# Make Project Libre "Cloud Ready"
#
# This is macOS only!
#
# This is a wrapper script for ProjectLibre.app (brew install projectlibre)
# that creates a lock file a along side with the opened file to prevent
# opening it twice. This is done because we wnat to share the project in our
# cloud storage.
#
# This is not 100 % safe. There may be soem seconds this implementation is
# vulnarable on concurrent file modifications. But itis better than nothing to prevent
# lost updates.
#

USAGE="Usage: $(basename "$0") <path/to/file.pod>"

echo_err() {
    >&2 echo "${1}"
}

acquire_lock() {
    local pod_file_lock
    pod_file_lock="${1}"

    echo "Try to get lock..."

    if [[ -e "${pod_file_lock}" ]]; then
        echo_err "Error: Can't acquire lock! Lock file '${pod_file_lock}' already exists."
        exit 1
    fi

    touch "${pod_file_lock}"
    echo "$USER:$(date)" > "${pod_file_lock}"
    echo "Lock file written: ${pod_file_lock}"
}

release_lock() {
    local pod_file_lock
    pod_file_lock="${1}"

    if [[ -e "${pod_file_lock}" ]]; then
        rm -rf "${pod_file_lock}"
        echo "Lock released."
    else
        echo_err "Warning: Can't release lock! Lock file '${pod_file_lock}' does not exist exists."
    fi
}

open_project_libre() {
    local pod_file
    pod_file="${1}"

    open --wait-apps -a ProjectLibre "${pod_file}"
}

main() {
    if [[ "$#" != "1" ]]; then
        echo_err "Error: Wrong number of arguments! Only one path to .pod file allowed as argument."
        echo_err "$USAGE"
        exit 1
    fi

    local pod_file pod_file_lock
    pod_file="${1}"
    pod_file_lock="${pod_file}.locked"

    acquire_lock "${pod_file_lock}"
    open_project_libre "${pod_file}"
    release_lock "${pod_file_lock}"
}

main "$@"

Instead of directly open Project Libre via open -a ProjectLibre file.pod or double clicking the file, you call the above script disco file.pod. (I named it “disco” for reasons™.)

You can install Project Libre via brew: brew instal projectlibre

The locking works quite simple: On opening the file there is a prior check if there is a file named same as the file to open with extension .locked. If it exists the script aborts with an error message. If it is absent it creates the lock file and opens it. In the lock file the $USER and current date is printed. This is helpful to identify the last person who locked the file.

Of course, this is not a perfect solution. There may be a small time gap for race conditions: It takes some time to sync my local lock file via cloud storage to all my team mates. But, I think this solution is beter than remebering to tell everyone in the team to not open the file or lock it manually in theOneDrive web UI.

Cover image by Alex Lion from Unsplash.