Contributing to an Open Source Project: OpenStack 31 Jan 2014

I’ve been working on OpenStack for a little over three months now and it has been a great experience: not only I’m being paid to write code that is used by millions of people, this code is also freely available for people to read and improve as they see fit. Having used opensource software for a long time now, working in an opensource project had been in my checklist of things to do as a developer and it’s been a great pleasure to be able to give it back to the community as my full-time job and fulfill my desire.

The Project

OpenStack is an infrastructure as a service cloud computing platform. It aims to provide all resources needed to run a cloud service: authentication system, compute instances, storage devices, network management, and, more recently, an orchestration system as well. It started in 2010 in a partnership between Rackspace and NASA, with the initial code being from both NASA’s Nebula platform and Rackspace’s Cloud Files.

The project I’m currently working on is Heat. It is the service responsible for the orchestration features of OpenStack and it aims to make it easy to create and manage the entire cloud application using templates. That means that you can spin up webservers, put them behind a load balancer, hook everything up to your database cluster, and deploy your application, without having to worry about the nitty-gritty of doing all that manually. When you want to scale your deployment and add more webservers, just edit the template to reflect the new count and update your application!


There are over 200 companies involved in OpenStack (Red Hat, IBM, HP, and Rackspace to name a few), 17 of which have contributed to Heat, plus independent contributors. A total of 69 different developers have contributed code to Heat (~30 of which are active and constantly submitting new code), and they are scattered around several different countries and timezones.


Most of our interaction takes place on IRC and you can always find folks hanging out on Freenode’s #heat. Come by and drop us a line! Everybody is really friendly and always willing to help out. IRC is used to chat pretty much about everything related to the project: general questions about the code, the direction the project is taking, current code reviews, bug, or blueprints (more on that later), or something else you can come up with.

Outside of IRC, a lot of discussion also happens on our mailing list. It is usually used for discussions where the input of a larger crowd is needed - you won’t be able to find all core members on the IRC channel at once, or the subject is too complex to be solved in quick (and sometimes even really long) chats.


It’s not because it’s an opensource project and most interaction happens on the internet that we do not have meetings. You can’t scape them! We hold weekly meetings that - now in an alternating schedule - happen at two different times to accomodate members that happen to live in very different timezones. It’s not fair that all meetings happen at 2am your time.

The weekly meetings are one hour long and promptly start at 2000 UTC on Wednesdays every other week, and at 0000 UTC on Thursdays the remaining weeks. They are facilitated by the project team lead and he’s responsible for guiding everybody through the weekly agenda and for making sure everybody stays on topic. There is also a special guest that is present in every meeting: an eavesdrop IRC bot called Meetbot and it plays a crucial role in making it easy to hold these meetings on IRC.


The code is all written in Python. We use Launchpad to track bugs and blueprints (specification and implementation of new features). This is primarily so that we can track progress of milestones and issue triage.

Once you get a bug or a blueprint and actually do some coding, then we use Gerrit to do code review. The review process is very straight-forward:

  1. Submit a patch for review
  2. Jenkins runs automated unit and functional tests and votes
  3. Members vote on your patch, possibly with reasons/questions
  4. If approved, Jenkins merges your patch with the repo

Both Jentkins and members vote on your patch. Once Jenkins finishes running all the tests, it’ll give either a -1 if tests fail or a +1 if they pass. After that, members will cast their votes ranging between -2 and +2. Once you get two core members to give you a +2, your code gets merged. The score meaning is as follows:

  • -2: this patch will never be accepted (core members only)
  • -1: I would prefer you didn’t merge this
  • 0: Used mostly for questions/comments
  • +1: Looks good to me, but someone else must approve
  • +2: Approved (core members only)

The scrutiny around each patch is very healthy for the most part and you get many developers examining your code for potential bugs, design flaws, or other pertinent details. That is a very good way of learning and constantly improve everybody’s code, since folks with more experience or that are more familiar with the codebase can spot things that would be harder for a newcomer to see at first. Though, good for the most part, the delay in certain reviews due to different timezones, too much work on core members, or just plain disagreements can be frustating at times.


All in all, working in an opensource project has been a great professional experience and it feels amazing to be able to spend my full time giving back to the community a little bit of my contribution. Have you ever contributed to an open project?