Why Branching still has a Place in the Agile World

I’m sure every developer out there would love to have a single code base with builds which are automatically tested and pushed out to customers. However, let’s assume for a moment that you’ve not got a full CI system with triggered builds, automated testing, and thousands of automated deployments a day.

For the sake argument let’s say you’ve got some of these pieces in place. Perhaps you have nightly builds? Maybe even some unit tests! But if you’re like most of the companies I’ve worked with you still run manual signoff scripts and have a couple of guys who do the deployments, know every config setting by heart and can get your application to run in all kinds of new and innovative ways.

Despite what The Phoenix Project tells us deployments to customers are still a big deal and version management (finding a way to release bug fixes but not new features) is a fact of life.

If your customers are anything like mine they’ll be incredibly nervous about taking new features. They want lengthy UAT phases and opportunities to train their staff on new functionality. This may seem like Waterfall to us, but remember many of our clients have stakeholders in some very big business. In my industry (Health and Leisure) for example we have code freezes over the January period while New Years Resolutioners and marketing campaigns are at their peak. Very few businesses would open themselves up to the risk of IT failures during these critical times.

And yet support contracts and maintenance doesn’t stop. The busy times are when the software is really put to the test and we must be able to respond to any issue which may arise.

This is why we use maintenance branches.

Our job as developers and IT professionals is to deliver a good service to our customers. We need tools and processes to do this. Agile and Continuous Integration are two of those tools but if they don’t help us meet business needs then we should seek others which do.

My customers tell me that they want to be able to take patches quickly if required. That they want to be able to access fixes without the need to test and learn new functionality.

Techniques such as feature toggles help but in my view the only way to truly meet this need is to cut a release branch after each feature (or for convenience block of features) is completed. We usually use a minor version to represent this. Using this model we can support customers without surprising them with new functionality and continue to develop knowing that we can put out maintenance releases of older version at any time.

Controversial? Perhaps, practically over purity… I hope so. What are your views or release branches and support customers with on premise installations?

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