Contributing a patch to the Firefox Marketplace from scratch

Jared, Stuart, and Andy recently spent some time focusing on one of the Marketplace’s biggest hurdles for new contributors: how do I get all these moving pieces set up and talking to each other?

I haven’t written a patch for the Marketplace in a while so I decided to see what all the fuss was about. First up I, of course, read the installation documentation. Ok, I skimmed it, but it looks pretty straight forward.

Step 1: Install Docker

I’m running Ubuntu so that’s as easy as:

sudo apt-get install docker.io

To fix permissions (put your own username instead of clouserw):

sudo usermod -a -G docker clouserw

Step 2: Build Dependencies

The steps below had lots of output which I’ll skip pasting here, but there were no errors and it only took a few minutes to run.

$ git clone https://github.com/mozilla/wharfie $ cd wharfie $ bin/mkt whoami clouserw $ bin/mkt checkout $ mkvirtualenv wharfie $ pip install --upgrade pip $ pip install -r requirements.txt $ sudo sh -c "echo 127.0.0.1 mp.dev >> /etc/hosts"

Step 3: Build and run the Docker containers

I ran this seemingly innocent command:

$ fig build

And 9 minutes and a zillion pages of output later I saw a promising message saying it had successfully built. One more command:

$ fig up

and I loaded http://mp.dev/ in my browser:

A weird empty home page, but it’s a running version of the Marketplace on my local computer! Success! Although, I’m not sure it counts unless the unit tests pass. Let’s see…

$ CTRL-C # To shutdown the running fig instance $ fig run --rm zamboni python ./manage.py test --noinput -s --logging-clear-handlers [ ...] Ran 4223 tests in 955.328s FAILED ( SKIP = 26, errors = 34, failures = 17 )

Hmm…that doesn’t seem good. Apparently there is some work left to get the tests to pass. I’ll file bug 1082183 and keep moving. I know Travis-CI will automatically run all the tests on any pull request so any changes I make will still be tested – depending on the changes you make this might be enough.

Step 4: Let’s write some code

If I were new to the Marketplace I’d look at the Contributing docs and follow the links there to find a bug to work on. However, I know Bug 989121 - Upgrade django-csp has been assigned to me for six months so I’m going to do that.

I’ll avoid talking about the patch since I’m trying to focus on the how and not the what in this post. The code is all in the /trees/ subdirectory under wharfie, so I’ll go there to write my code. A summary of the commands:

$ cd trees/zamboni $ vi <files> # Be sure to include unit tests $ git add <files> $ git checkout -b 989121 # I name my branches after my bug numbers $ git commit # commit messages must include the bug number $ git push origin 989121

Now my changes are on Github! When I load the repository I committed to in my browser I see a big green button at the top asking if I want to make a pull request.

I click the button and submit my pull request which notifies the Marketplace developers that I’d like to merge the changes in. It will also trigger the unit tests and notify me via email if any of them fail. Assuming everything passes then I’m all done.

This flow is still a little rough around the edges, but for an adventurous contributor it’s certainly possible. It looks like Bug 1011198 - Get a turn-key marketplace dev-env up and running is tracking progress on making this easier so if you’re interested in contributing feel free to follow along and jump in when you’re comfortable.