Big thanks Fabien
Sent from my iPhone
On 17-09-2012, at 12:01, Fabien Potencier
> My keynote last week at Symfony Live London was about adopting a formal release process. In fact, I've talked about adopting a shorter release cycle for Symfony for quite some time now, and I think that this is the right time to discuss it.
> As we have all noticed, Symfony enjoys a large community of "core" developers: a core developer being someone who contribute to Symfony on a regular basis. The flow of pull requests has been outstanding and steady for the past two years, and with such an activity, trying to release often without a clear roadmap is quite difficult. Adopting a more formal release cycle will also give more visibility to the contributors and allow for everyone to understand when a new feature might be available in Symfony.
> So, here is my initial proposal, which is the one I've talked about during Symfony Live and of course, it is up for discussion. I would like to apply the new release process as soon as possible and if possible for Symfony 2.2. And whenever we all agree on the final version of this proposal, it will be included in the official Symfony documentation.
> This release process only applies to the code hosted on the symfony/symfony repository, but of course, I hope that third-party code related to Symfony (like the Symfony bundles) will also adopt it (at least, just for the timeline).
> Let's list the goals for the new process:
> * Shorten the release cycle;
> * Keep backward compatibility as much as possible;
> * Enhance the overall quality of the framework (not just the code, but documentation, bundles, ...);
> * Give more visibility to our "customers": developers using the framework to get their job done and Open-Soure projects using/embedding Symfony;
> * Improve the experience of Symfony core contributors by controlling the flow of incoming pull requests (why pull requests are not always merged right away? when will a new feature be merged? when breaking BC is acceptable? ...);
> * Coordinate our timeline with projects that we are using (Doctrine, Propel, Monolog, Assetic, Twig, ...) but also with projects that are using/embedding Symfony;
> * Give time to the Symfony ecosystem to catch up with the new versions (bundleauthors, documentation writers, translators, ...);
> That's a lot to take care of!
> So, without further ado, here is my plan.
> Historically, we've been able to release a new major version every year since 2005. Nothing was even written about that, but that's what we did.
> From now on, I propose to adopt a *time-based model* for Symfony and I think that having a new major release every six months is a good compromise: it gives plenty of time to work on new features but it also allows for non-ready features to be postponed to the next version (without having to wait too much for the next cycle).
> Six months should be fast enough for developers who want to work on the latest and the greatest; but at the same time, companies might want more time to learn and upgrade. The way to make everyone happy is to ensure an easy upgrade path from one version to the next one. Take Twig as an example: I've been able to release a new major version every month and a half since 1.0; that's very fast and it has been possible because we've kept backward compatibility between all major releases (and of course the scope of Twig is also smaller).
> Six month releases mean that two releases fit in a year and so, everybody knows when releases will be made without having to check on the website: for Symfony it will be at the end of May and at the end of November of each year. That brings predictability and visibility.
> The key is keeping backward compatibility. We must be much more careful when breaking backward compatibility; and the possibility to break backward compatibility depends on the component we are talking about. The following components must never break backward compatibility because they are the low-level architecture of the framework and also because so many people rely on them:
> * ClassLoader
> Backward compatibility should be easy to keep for the following components:
> * BrowserKit
> And these components should probably become more stable soon, but that's not that easy (yet):
> * Config
> Six months can be seen as a rather short period to make a new release, especially if we look at what we did in the past. I think we can make it work because we have now more people able to help, but also because the six month period itself should be cut in shorter periods:
> * Development: 4 months to add new features and to enhance existing ones;
> * Stabilisation: 2 months to fix bugs, prepare the release, and wait for the whole ecosystem to catch up.
> During the development phase, we can revert any new feature if we think that we won't be able to finish it in time or if we think that it won't be stable enough to be included.
> During the stabilisation phase, some developers might still work on new features for the next version, but it would be better if most developers can concentrate on finishing the current version.
> By the way, when I have a look at the pull requests today, I think that we already have enough features for Symfony 2.2.
> Long Term Support release
> We've not yet published our LTS release for Symfony2. As I mentioned it in the past, the first LTS should be Symfony 2.3.
> Each LTS release will be supported for a 3 year period but it will also be supported for at least a year after the next LTS is released. So, it means that we are going to release a new LTS version every two years.
> This dual release cycle should make everyone happy. If you are a fast mover, you want to work with the latest and the greatest, stick with the standard support releases: you have a new version every six months, and you have two months to upgrade to the next one. If you are a big company, and you want more stability, stick with the long term support releases: you get a new version every two years and you have a year to upgrade.
> To make things more concrete, here is the schedule for the next few versions:
> * Symfony 2.2 will be released at the end of February 2013;
> * Symfony 2.3 (the first LTS) will be released at the end of Mai 2013 (only 3 months after 2.2 as it will be a "special" release in the sense that we will mainly remove the 2.0 BC layer and also because I think that May and November are the best months for releases);
> * Symfony 2.4 will be released at the end of November 2013;
> * Symfony 2.5 will be released at the end of Mai 2014;
> * ...
> So, why not releasing Symfony 2.2 earlier as we already have so many features waiting in the pull request queue? Because of the next section: this is our last chance to break backward compatibility.
> Symfony 3.0
> After the release of Symfony 2.3, backward compatibility will be kept at all cost. If it is not possible, the feature/enhancement will be scheduled for Symfony 3.0. And the work on 3.0 will start whenever we think that we have enough great features under our belt to make it worth it.
> After Symfony 2.3, non LTS releases will be maintained for 8 months to give people plenty of time to upgrade (keep in mind that even if no BC breaks will have occurred, you might need to upgrade your applications to benefit from the new features and the new best practices).
> To make the new process works well (no BC and a fixed schedule), we need to formalise the contribution process a bit more. Every new Symfony feature or enhancement must be worked on via Git pull requests. A few months ago, we formalised the pull request process a bit by adding a required [header](http://symfony.com/doc/current/contributing/code/patches.html#make-a-... list. But I've done a poor job in enforcing the rule. So, I'm going to be uncompromising about it now and at the same time I'd like to introduce even more checks in the list.
> A pull request will only be merged if the following rules are met:
> * The code is correct and it uses the Symfony way of doing things (naming conventions, coding standards, ...);
> * The new code is tested (or the bug to fix is covered by tests) and all the tests pass on all supported PHP versions;
> * The documentation has been updated (with a pending pull request on symfony/symfony-docs);
> * The changelog and upgrade files have been updated;
> * No backward compatibility break has been introduced;
> * If it is a fix, it has been applied to the oldest and still supported Symfony version;
> * For major features, a RFC has been written, discussed, and approved.
> As I said at the beginning, this is a draft, and you are all welcome to chime in and propose changes.
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