Cloud Foundry is an Open Platform-as-a-Service, and an Open Source project. It has attracted phenomenal interest from the community - including partners, companies using the code internally, and those individual developers with a passion for getting involved. You can find the source code on Github. Community contributions are what help to make the platform so extensible. We are always happy when we receive a Github pull request to offer new functionality or fixes! We also appreciate bug reports submitted through Github Issues.

Looking at the Cloud Foundry project as a whole though… where should you start?

As you might imagine, there are a lot of moving parts in a PaaS. At Pivotal, we have teams working on the backend (the main runtime environment for Cloud Foundry, also known as ‘vcap’); the frontend (the tools and APIs for deploying apps, such as the ‘cf’ gem); services (database, message queues, and related resources); and Cloud Foundry BOSH, the installer and deployment tool, which has different plugins targeting infrastructures like AWS, OpenStack and vSphere. In the future, we would love to see even more Cloud Provider Interfaces (CPIs) for BOSH to allow Cloud Foundry to be deployed onto additional clouds.

One of the best ways to get involved with the community and the codebase is to start with the Github repositories and the mailing lists. If you are not sure where particular functionality resides within the project as a whole, and you’ve had a good look at Github already, then we have a number of mailing lists where you can ask for help. vcap-dev is for those working on the PaaS itself; bosh-users is for those who want to understand how to use BOSH to deploy Cloud Foundry; and bosh-dev is for the elite hackers (like Dr Nic Williams!) who want to help us make BOSH even more awesome. If you participate in the mailing lists you will also be able to keep up with what others are working on, and learn who some of the leading developers on the project are. If you want to get an idea of the general direction of development, you’ll find that in our roadmap.

Once you are up-and-running with Cloud Foundry, or if you know to which part of the project  you want to contribute, then consider the size of an initial contribution. If you are new to the project you might want to start with something small (some Open Source projects call these kind of small changes to smooth out any rough edges “paper cuts”). If you have something larger, we are always keen to work with you to understand how we can integrate your code. Before sending a pull request, take a look at our OSS contribution information in the project readme, which includes details on the Contributor License Agreement for individuals and corporations.

We thought it would be good to highlight a recent pull request which was a superb example of a major addition to the project. Recently we received a contribution via a detailed Github pull request, adding Oracle support to some of the major components inside Cloud Foundry: the User Account and Authentication service (UAA) and the Cloud Controller. Originally, these components were built to use Postgres as a backend, and more recently MySQL support was added. Since many enterprises already use Oracle as their main relational data store, it is great to give them this additional storage option.

Taking a look at the specific request for the Cloud Controller, we were really struck by a few things. The first one is that the pull request itself is very detailed, and walks through the various changes required in order to replace the database with Oracle.

This pull request is a lot to digest. If you want you can review the single feature PR that lead to this PR for some more concise context into some of the decisions I made in creating this PR. Here is a summary of the more notable changes I had to make and some context for why I made those changes:

This level of detail is not always required with every patch, of course, but for something this extensive it was very welcome. Another aspect of this patch is that was was made of up several individual changes (things like tweaks to the database schema, differences between Oracle datatypes and those used by other databases, etc), and they were broken down into separate commits which made it easier to consume. It also helped that this set of changes was extensively discussed on the vcap-dev mailing list before this larger pull request was submitted, so the engineering team were aware of some of the other impacts it would have.

Although the resulting pull request was detailed and clear, it has taken a few days to make all of the changes, as the core code was still being worked on. This was actually one of the rarer cases where we had to do more work to get the patches integrated – and that shows how willing we are to work with contributions. Smaller changes are extremely welcome too, and often much quicker to digest. Don’t be put off by this larger example – come and start hacking with us!

We hope this post highlights some of the things that help to make it smoother to contribute to the project. To recap:

1. review the contribution guidelines and complete the CLA;
2. if you want to submit a major code change, discuss it on the relevant mailing list beforehand;
3. think about how the pull request is structured, and submit changes in separate consumable commits (rather than as one monolithic change) where appropriate;
4. the patch should be well-tested, should include tests if possible, and should pass our Travis CI process;
5. the changes should be clearly documented in the request, especially when the updates are more extensive than correcting a few typos.

The past few months have seen the Cloud Foundry Open Source community grow hugely, and mailing list activity continues to be at an all-time high – so we’re really looking forward to continuing to work with other developers to make the platform even more awesome! Thanks for being on this journey with us.

Andy Piper @andypiper

Developer Advocate, Cloud Foundry