Trello is an awesome producitvity tool that is especially great for real-time and asynchronous collaboration. Trello boards can be set to Public and are then available on the Internet.

A while back, I wrote a Python utility called trello-public-board-lister that used the Trello API to return a list of all of the Public boards owned by a Trello user that I specified. I picked it back up recently and extended the functionality:

Automated the process via GitLab CI
Published sample urlwatch configs for monitoring changes

Who cares?

Consider Kushagra Pathak's work on: How I used a simple Google query to mine passwords from dozens of public Trello boards. It ultimately led to this write-up in The Intercept: United Nations accidentally exposed passwords and sensitive information to the whole Internet.

It's trivially easy to find public Trello boards. It's easy for your team and it's easy for the adversary.
Trello has increasingly turned toward addressing the enterprise use case.

Be aware of your Trello board footprint before it becomes a problem.

If you are using Trello in your organization, you may wish to have some process that regularly checks to see what public boards are present in your environment and lets you make sure this list only contains the boards that you expect. This post describes an approach to solving this problem and some code you can borrow, modify and implement.

Preparation

Before you run trello-public-board-lister, you need to have a list of Trello usernames and a Trello API key and token.

Provide a list of usernames

Put the list of usernames you want to monitor in a file, one-per-line.

Get Trello API key and token

Log in to Trello and then browse to https://trello.com/app-key.

Record the Key that is shown securely
Click Token, follow the dialogs and record the Token that is shown securely

Run trello-public-board-lister

Run trello-public-board-lister manually to make sure everything works as you expect and then automate the process with a CI pipeline. You'll want to run all of these commands in the same terminal session.

git clone git@gitlab.com:brie/trello-public-board-lister.git

Run manually

I recommend using a Python virtual environment. Instructions on setting up a virtual environment don't belong in this blog post but Corey Schafer has fantastic Python videos on Python.

Change into the cloned directory, create a new virtual environment, activate it and install the required Python packages for trello-public-board-lister:

cd trello-public-board-lister
python3 -m venv v
source v/bin/activate
pip install -r requirements.txt

Make the Trello API key and token available

You have two options:

environment variables
command line arguments

I recommend using environment variables.

export TRELLO_API_KEY=yourtrelloapikey
export TRELLO_API_TOKEN=yourtrelloapitoken

OK, go!

Everything should be all ready. Copy your list of Trello usernames into this directory. Run:

python3 trello-public-board-lister.py --usernames trello-usernames.txt

You should see output like this:

output

For each username provided, you will have a .boards file containing a JSON object that includes the URL for each public Trello board for that user. You can use jq to count the URLs in each file:

$ jq '. | length' taco.boards
8

If everything is looking OK, you can move on to automating and scheduling. Feel free to fork trello-public-board-lister and patch it to work to better meet your needs.

Automate the process with a CI pipeline

Let's set up GitLab to run this whole process as a CI pipeline on a schedule.

Create a project in your GitLab instance for this purpose.

Add Trello API key and token as masked variables in GitLab

We are going to continue using environment variables to tell trello-public-board-lister.py about our Trello API key and token. When running this program in a GitLab pipeline, we do this by defining masked custom environment variables. For both TRELLO_API_KEY and TRELLO_API_TOKEN, do:

Hover over Settings and then click CI / CD
Expand Variables
Click Add Variable

The Key should be: TRELLO_API_KEY For the Value, copy in your Trello API key Uncheck Protect variable Make super sure that you click Mask variable

When that's all done: click Add variable

It should look something like this:

masked custom environment variables

The environment variables are all set!

Build a pipeline

I have a sample .gitlab-ci.yml file that you can modify and use to run this pipeline via GitLab:

.gitlab-ci.yml from gitlab.com/brie/check-for-public-trello-boards

Schedule the pipeline

You can configure a pipeline schedule so that everything runs and checks for public Trello boards at the frequency that is right for you.

Check for changes

Once you have an initial list of boards that are public, you may wish to check for changes in that list. I use urlwatch, a tool that monitors webpages for you for this purpose.

add a job to check for changes in list of boards
Send changes by email via built-in Mailgun reporter

Recap

If you played along, you now have a process that checks for public Trello boards from a list of users that you care about. This process runs periodically and alerts you to changes in the list of public Trello boards.